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North American X-15
From Wikipedia, the free encyclopedia
X-15
Role
Experimental high-speed rocket-powered research aircraft
Manufacturer: North American Aviation
First flight: 8 June 1959
Introduced: 17 September 1959
Retired: December 1970
Primary users: United States Air Force and NASA
Number built: 3
The North American X-15 rocket-powered aircraft/spaceplane was part of the X-series of experimental aircraft, initiated with the Bell X-1, that were made for the USAAF/ USAF, NACA/NASA, and the USN. The X-15 set speed and altitude records in the early 1960s, reaching the edge of outer space and returning with valuable data used in aircraft and spacecraft design. As of 2011, it holds the official world record for the fastest speed ever reached by a manned rocket-powered aircraft.[1]
During the X-15 program, 13 of the flights (by eight pilots) met the USAF spaceflight criteria by exceeding the altitude of 50 miles (80.5 km, 264,000 ft), thus qualifying the pilots for astronaut status. The USAF pilots qualified for USAF astronaut wings, while the civilian pilots were later awarded NASA astronaut wings.[2][3]
Of all the X-15 missions, two flights (by the same pilot) qualified as space flights per the international (Fédération Aéronautique Internationale) definition of a spaceflight by exceeding 100 kilometres (62.1 mi, 328,084 ft) in altitude.
Contents
Design and development
X-15 just after release.
X-15 touching down on its skids. Compare jettisoned lower ventral fin with color picture, top.
The X-15 was based on a concept study from Walter Dornberger for the NACA for a hypersonic research aircraft.[4] The requests for proposal were published on 30 December 1954 for the airframe and on 4 February 1955 for the rocket engine. The X-15 was built by two manufacturers: North American Aviation was contracted for the airframe in November 1955, and Reaction Motors was contracted for building the engines in 1956.
Like most X-series aircraft, the X-15 was designed to be carried aloft, under the wing of a NASA B-52, the Balls 8. Release took place at an altitude of about 8.5 miles (13.7 km, 45,000 ft), and a speed of about 805 km/h (500 mph, 223.5 m/s).[5] The X-15 fuselage was long and cylindrical, with rear fairings that flattened its appearance, and thick, dorsal and ventral wedge-fin stabilizers. Parts of the fuselage were heat-resistant nickel alloy (Inconel-X 750).[4] The retractable landing gear comprised a nose-wheel carriage and two rear skis. The skis did not extend beyond the ventral fin, which required the pilot to jettison the lower fin (fitted with a parachute) just before landing. The two XLR-11 rocket engines for the initial X-15A model delivered 16,000 lbf (71 kN) maximum thrust each, for a total of 32,000 pounds-force. The main engine (installed later) was a single XLR-99 rocket engine delivering 57,000 lbf (250 kN) at sea level, and 70,000 lbf (310 kN) at peak altitude. The idle thrust of the XLR-99 was 15,000 lbf (67 kN).
Engines and fuel
Early flights used two Reaction Motors XLR11 engines. Later flights were undertaken with a single Reaction Motors Inc XLR99 rocket engine generating 57,000 pounds-force (250 kN) of thrust powered the aircraft. This engine used ammonia and liquid oxygen for propellant and hydrogen peroxide to drive the high-speed turbopump that delivered fuel to the engine. The XLR99 could be throttled, and were the first such controllable engines that were "man-rated",[disputed – discuss] that is, declared safe to operate with a human aboard.[citation needed]
Operational history
Three X-15s were built, flying 199 test flights, the last on 24 October 1968. The first X-15 flight was an unpowered test flight by Scott Crossfield, on 8 June 1959; he also piloted the first powered flight, on 17 September 1959, with his first XLR-99 flight on 15 November 1960. Twelve test pilots flew the X-15; among them were Neil Armstrong (first man to walk on the moon) and Joe Engle (later a space shuttle commander). In July and August 1963, pilot Joe Walker crossed the 100 km altitude mark, joining the NASA astronauts and Soviet Cosmonauts as the first humans to have crossed the barrier into outer space (Soviet Yuri Gagarin was the first person in space, reaching 327 km in apogee of his orbital flight, while Alan Shepard was the first American in space, reaching 187 km during suborbital flight) and becoming the first to exceed this threshold twice.
U.S. Air Force test pilot Major Michael J. Adams was killed on 15 November 1967 in X-15 Flight 191 when his craft (X-15-3) entered a hypersonic spin while descending, then oscillated violently as aerodynamic forces increased after re-entry. As his craft's flight control system operated the control surfaces to their limits, the craft's acceleration built to 15 g vertical and 8 g lateral. The airframe broke apart at 60,000 ft (18,000 m) altitude, scattering the craft's wreckage for 50 square miles (130 km2). On 8 June 2004, a monument was erected at the cockpit's locale, near Randsburg, California.[6] Major Adams was posthumously awarded Air Force astronaut wings for his final flight in craft X-15-3, which had reached 81.1 km (50.4 mi, 266,000 ft) of altitude. In 1991, his name was added to the Astronaut Memorial.
Bomber NB-52A (s/n 52-003), permanent test variant, carrying an X-15, with mission markings; horizontal X-15 craft silhouettes denote glide flights, diagonal silhouettes denote powered flights.
The second X-15A was rebuilt after a landing accident. It was lengthened 2.4 feet (0.73 m), a pair of auxiliary fuel tanks attached under the fuselage, and a heat-resistant surface treatment applied. Re-named the X-15A-2, it first flew on 28 June 1964, reaching 7,274 km/h (4,520 mph, 2,021 m/s).
The altitudes attained by the X-15 aircraft do not match that of Alan Shepard's 1961 NASA space capsule flight nor subsequent NASA space capsules and space shuttle flights. However, the X-15 flights did reign supreme among rocket-powered aircraft until the second spaceflight of Space Ship One in 2004.
Five aircraft were used for the X-15 program: three X-15s, two B-52 bombers:
X-15A-1 – 56-6670, 82 powered flights
X-15A-2 – 56-6671, 53 powered flights
X-15A-3 – 56-6672, 64 powered flights
NB-52A – 52-003 (retired in October 1969)
NB-52B – 52-008 (retired in November 2004)
A 200th flight over Nevada was slated for 21 November 1968, piloted by William J. Knight. Technical problems and bad weather delayed the flight six times, and on 20 December 1968, the 200th flight was finally cancelled. The X-15 was detached from the NB-52A wing and prepared for indefinite storage.
Gallery
X-15 gallery
X-15A-2 on the flight line
X-15 on Boeing B-52 Mothership wing pylon
X-15 in full scale ablative coating
X-15 on display at the National Air and Space Museum
X-15 nose
Current static displays
X-15 at the National Air and Space Museum X-15-1 (s/n 56-6670) is on display in the National Air and Space Museum "Milestones of Flight" gallery, Washington, D.C.
X-15-2A (s/n 56-6671) is at the National Museum of the United States Air Force, at Wright-Patterson Air Force Base, near Dayton, Ohio. It was retired to the Museum in October 1969.[7] The aircraft is displayed in the Museum's Research & Development Hangar alongside other "X-planes", including the Bell X-1 and X-3 Stiletto.
X-15-3 (s/n 56-6672) was destroyed. Parts have been recovered at the crash site as late as the 1990s.
X-15A2 with external fuel tanks, white ablative paint, and mock-up of "Scram-Jet" engine.
The Scram-Jet engine project was never completed, and only the non-functional mock-up was flight
tested. The Scram-Jet mockup is on display at the US Air Force Museum in Dayton Ohio.
Mock-ups
Dryden Flight Research Center, Edwards AFB, California, USA (painted with s/n 56-6672)
Pima Air Museum, Tucson, Arizona (painted with s/n 56-6671)
Evergreen Aviation Museum, McMinnville, Oregon (painted with s/n 56-6672). A full-scale wooden mock-up of the X-15, displayed along with one of the rocket motors.
Stratofortress motherships
NB-52A (s/n 52-003) is at the Pima Air and Space Museum, Tucson, Arizona. It launched the X-15 #1 30 times, the X-15 #2, 11 times, and the X-15 #3 31 times (as well as the M2-F2 four times, the HL-10 11 times and the X-24A twice).
NB-52B (s/n 52-008) is at the Dryden Flight Research Center, Edwards AFB, California, USA. It launched the majority of X-15 flights.
Aftermath
Before 1958, USAF and NACA, (later NASA), officials discussed an orbital X-15 spacecraft—the X-15B—for launching to outer space atop an SM-64 Navajo missile. This was canceled when NACA became NASA, and Project Mercury was approved instead. By 1959, the X-20 Dyna-Soar space-glider program became the USAF's preferred means for launching military manned spacecraft into orbit; however, this program was canceled in the early 1960s before an operational vehicle could be built.[2]
Record flights
Highest flights
There are two definitions of how high a person must go to be referred to as an astronaut. The USAF decided to award astronaut wings to anyone who achieved an altitude of 50 miles (80.5 km) or more. However, the FAI set the limit of space at 100 kilometres (62.1 mi). Thirteen X-15 flights went higher than 50 miles and two of these reached over 100 kilometres.
X-15 flights higher than 50 mi (80 km)
Flight Flight 62 Flight 77 Flight 87
Date 17 July 1962 17 January 1963 27 June 1963
Top speed 3,831 mph (6,165 km/h) 3,677 mph (5,918 km/h) 3,425 mph (5,512 km/h)
Altitude 59.6 miles (95.9 km) 51.4 miles (82.7 km) 53.9 miles (86.7 km)
Pilot Robert M. White Joe Walker Robert Rushworth
Flight Flight 90 Flight 91 Flight 138
Date 19 July 1963 22 August 1963 29 June 1965
Top Speed 3,710 mph (5,970 km/h) 3,794 mph (6,106 km/h) 3,431 mph (5,522 km/h)
Altitude 65.8 miles (105.9 km) 67.0 miles (107.8 km) 53.1 miles (85.5 km)
Pilot Joe Walker Joe Walker Joseph H. Engle
Flight Flight 143 Flight 150 Flight 153
Date 10 August 1965 28 September 1965 14 October 1965
Top Speed 3,549 mph (5,712 km/h) 3,731 mph (6,004 km/h) 3,554 mph (5,720 km/h)
Altitude 51.3 miles (82.6 km) 55.9 miles (90.0 km) 50.4 miles (81.1 km)
Pilot Joseph H. Engle John B. McKay Joseph H. Engle
Flight Flight 174 Flight 190 Flight 191
Date 1 November 1966 17 October 1967 15 November 1967
Top Speed 3,750 mph (6,040 km/h) 3,856 mph (6,206 km/h) 3,569 mph (5,744 km/h)
Altitude 58.1 miles (93.5 km) 53.1 miles (85.5 km) 50.3 miles (81.0 km)
Pilot Bill Dana Pete Knight Michael J. Adams†
Flight Flight 197
Date 21 August 1968
Top Speed 3,443 mph (5,541 km/h)
Altitude 50.6 miles (81.4 km)
Pilot Bill Dana
† fatal
Fastest flights
X-15 10 fastest flights
Flight Flight 45 Flight 59 Flight 64
Date 9 November 1961 27 June 1962 26 July 1962
Top Speed 4,092 mph (6,585 km/h) 4,104 mph (6,605 km/h) 3,989 mph (6,420 km/h)
Altitude 19.2 miles (30.9 km) 23.4 miles (37.7 km) 18.7 miles (30.1 km)
Pilot Robert M. White Joe Walker Neil Armstrong
Flight Flight 86 Flight 89 Flight 97
Date 25 June 1963 18 July 1963 5 December 1963
Top Speed 3,910 mph (6,290 km/h) 3,925 mph (6,317 km/h) 4,017 mph (6,465 km/h)
Altitude 21.7 miles (34.9 km) 19.8 miles (31.9 km) 19.1 miles (30.7 km)
Pilot Joe Walker Robert Rushworth Robert Rushworth
Flight Flight 105 Flight 137 Flight 175
Date 29 April 1964 22 June 1965 18 November 1966
Top Speed 3,905 mph (6,284 km/h) 3,938 mph (6,338 km/h) 4,250 mph (6,840 km/h)
Altitude 19.2 miles (30.9 km) 29.5 miles (47.5 km) 18.7 miles (30.1 km)
Pilot Robert Rushworth John B. McKay Pete Knight
Flight Flight 188
Date 3 October 1967
Top Speed 4,519 mph (7,273 km/h)
Altitude 19.3 miles (31.1 km)
Pilot Pete Knight
X-15 pilots
X-15 pilots and their achievements during the program
Pilot Michael J. Adams† Neil Armstrong Scott Crossfield Bill Dana Joseph H. Engle
Organization USAF NASA North American NASA USAF
Aviation
Total 7 7 14 16 16
Flights
USAF 1 0 0 2 3
space
flights
FAI 0 0 0 0 0
space
flights
Max 5.59 5.74 2.97 5.53 5.71
Mach
Max 3,822 3,989 1,959 3,897 3,887
speed
(mph)
Max 50.3 39.2 15.3 58.1 53.1
altitude
(miles)
Pilot Pete Knight John B. McKay Forrest S. Petersen Robert A. Rushworth
Organization USAF NASA USN USAF
Total 16 29 5 34
Flights
USAF 1 1 0 1
Space
Flights
FAI 0 0 0 0
Space
Flights
Max. 6.70 5.65 5.3 6.6
Mach
Max. 4,519 3,863 3,600 4,017
Speed
(MPH)
Max. 53.1 55.9 19.2 53.9
Altitude
(Miles)
Pilot Milt Thompson Joe Walker Robert M. White*
Organization NASA USAF USAF
Total
Flights 14 25 16
USAF
Space
Flights 0 3 1
FAI
Space
Flights 0 2 0
Max.
Mach 5.48 5.92 6.04
Max.
Speed
(MPH) 3,723 4,104 4,092
Max.
Altitude
(Miles) 40.5 67.0 59.6
† Killed • * White was backup for Captain Iven Kincheloe
Specifications (X-15)
General characteristics
Crew: one
Length: 50 ft 9 in (15.45 m)
Wingspan: 22 ft 4 in (6.8 m)
Height: 13 ft 6 in (4.12 m)
Wing area: 200 ft2 (18.6 m2)
Empty weight: 14,600 lb (6,620 kg)
Loaded weight: 34,000 lb (15,420 kg)
Max takeoff weight: 34,000 lb (15,420 kg)
Powerplant: 1 × Thiokol XLR99-RM-2 liquid-fuel rocket engine, 70,400 lbf at 30 km (313 kN)
Performance
Maximum speed: Mach 6.72 (4,520 mph, 7,274 km/h)
Range: 280 mi (450 km)
Service ceiling: 67 mi (108 km, 354,330 ft)
Rate of climb: 60,000 ft/min (18,288 m/min)
Wing loading: 170 lb/ft2 (829 kg/m2)
Thrust/weight: 2.07
References
Notes
1.^ Aircraft Museum X-15." Aerospaceweb.org, 24 November 2008.
2.^ a b Jenkins, Dennis R. Space Shuttle: The History of the National Space Transportation System: The First 100 Missions, 3rd edition. Stillwater, Minnesota: Voyageur Press, 2001. ISBN 0-9633974-5-1.
3.^ "NASA astronaut wings award ceremony". NASA Press Release, 23 August 2005.
4.^ a b Käsmann 1999, p. 105.
5.^ "X-15 launch from B-52 mothership." Dryden Flight Research Center Photo Collection. Retrieved: 8 February 2011.
6.^ X-15A Crash site
7.^ United States Air Force Museum 1975, p. 73.
Bibliography
"SP-2000-4531: American X-Vehicles: An Inventory X-1 to X-50." NASA, June 2003.
"Flight experience with shock impingement and interference heating on the X-15-2 research airplane 1968." NASA.
Godwin, Robert, ed. X-15: The NASA Mission Reports. Burlington, Ontario: Apogee Books, 2001. ISBN 1-896522-65-3.
Hallion, Dr. Richard P. "Saga of the Rocket Ships." AirEnthusiast Six, March–June 1978. Bromley, Kent, UK: Pilot Press Ltd.
Käsmann, Ferdinand C.W. "Die schnellsten Jets der Welt". Weltrekord-Flugzeuge [World Speed Record Aircraft] (in German). Kolpingring, Germany: Aviatic Verlag, 1999. ISBN 3-925505-26-1.
"Thermal protection system X-15A-2 Design report." NASA report 1968 (PDF format).
Thompson, Milton O. and Neil Armstrong. At the Edge of Space: The X-15 Flight Program. Washington, DC: Smithsonian Institution Press, 1992. ISBN 1-56098-107-5.
Tregaskis, Richard. X-15 Diary: The Story of America's First Space Ship. Lincoln, Nebraska: iUniverse.com, 2000. ISBN 0-595-00250-1.
United States Air Force Museum Guidebook. Wright-Patterson AFB, Ohio: Air Force Museum Foundation, 1975.
"X-15 research results with a selected bibliography." NASA report (PDF format).
"X-15: Extending the Frontiers of Flight." NASA (PDF format).
Additional, from fighter-planes.com:
On the limit of aircraft and spacecraft, the X-15 reached Mach 6.72 and an height of 107960 m. The X-15 was designed to resist the heat and friction of atmospheric reentry. It was powered by rocket engines. The X-15A-2 version could carry two large external fuel tanks. Three X-15s were built, one was lost in a fatal accident.
Type: X-15A
Country: USA
Function: experimental
Year: 1959
Crew: 1
Engines: 1 * 31750 kg Reaction Motors XLR-99 (liquid-fuel rocket engine)
Wing Span: 6.71 m
Length: 15.24 m
Height: 4.12 m
Wing Area: 18.58 m2
Empty Weight: 6623 kg
Max.Weight: 15422 kg
Speed: 6600 km/h
Ceiling: 95900 m
Rate of climb: 18000 m/min
Range: 450 km
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The North American X-15 rocket plane was perhaps the most important of the USAF/USN X-series of experimental aircraft. Although not as famous as the Bell X-1, the X-15 set numerous speed and altitude records in the early 1960s, reaching the edge of space and bringing back valuable data that was used in the design of later aircraft and spacecraft.
During the X-15 program, 13 flights met the US criterion for a spaceflight by passing an altitude of 50 miles (80 km) and the pilots were accordingly awarded astronaut status by the USAF. Out of these, 2 also qualified for the international FAI definition of a spaceflight by passing the 62.1 miles (100 km) mark.
History
The original Request for Proposals was issued for the airframe December 30, 1954, and for the rocket engine on February 4, 1955. North American received the airframe contract in November 1955, and Reaction Motors contracted in 1956 to build the engines.
As with many of the X-aircraft, the X-15 was designed to be carried aloft under the wing of a B-52. The fuselage was long and cylindrical, with fairings towards the rear giving it a flattened look, and it had thick wedge-shaped dorsal and ventral fins. The retractable landing gear consisted of a nose wheel and two skids to provide sufficient clearance part of the ventral fin had to be jettisoned before landing. The two XLR-11 rocket engines of the initial model X-15A delivered 36 kN (8,000 lbf) of thrust; the "real" engine that came later was a single XLR-99 that delivered 254 kN (57,000 lbf) at sea level, and 311 kN (70,000 lbf) at peak altitude.
The first flight was an unpowered test made by Scott Crossfield on June 8, 1959, who followed up with the first powered flight on September 17. The first flight with the XLR-99 was on 15 November 1960.
Three X-15s were built in all, and they made a total of 199 test flights, the last one on October 24, 1968. Plans were made for a 200th X-15 flight to be launched over Smith Ranch, Nevada. It was scheduled for November 21, 1968 with William J. Knight as the pilot. Various technical and weather delays caused the planned launch to slip at least six times until late December, 1968. Finally after a cancellation on December 20, 1968 due to weather, it was decided there would not be a 200th flight. The X-15 ground crew de-mated the aircraft from the NB-52A, and prepared it for indefinite storage. X-15 #1 was sent to the National Air and Space Museum in Washington, DC. X-15 #2 is on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio. X-15 #3, 56-6672, was destroyed in a crash on November 15, 1967.
Twelve test pilots flew the plane, including Neil Armstrong, later the first man on the Moon and Joe Engle who went on to command Space Shuttle missions. In July and August, 1963, pilot Joe Walker crossed the 100 km altitude mark twice, becoming the first person to enter space twice.
Test pilot Michael J. Adams was killed on November 15, 1967 when his X-15-3 began to spin on descent and then disintegrated when the acceleration reached 15 g (147 m/s²), scattering wreckage over 50 square miles. On June 8, 2004 a memorial monument was erected at the location of cockpit crash site near Randsburg, California. Michael Adams was posthumously awarded astronaut wings for his last flight in the X-15-3, which had attained an altitude of 266,000 feet (81.1 Km). In 1991 Adams' name was added to the Astronaut Memorial at the Kennedy Space Center in Florida.
The second X-15A was rebuilt after a landing accident. It was lengthened by about 0.74 m (2.4 ft), received a pair of auxiliary fuel tanks slung under the fuselage, and was given a heat-resistant surface treatment, the result being called the X-15A-2. It first flew June 28, 1964, and eventually reached a speed of 7,274 km/h (4,520 mi/h or 2,021 m/s). The altitudes attained by the X-15 remained unsurpassed by any piloted aircraft except the Space Shuttle until the 3rd spaceflight of SpaceShipOne in 2004. The speeds and altitudes have, also, frequently been exceeded by unpiloted air-launched rockets, such as the Pegasus rocket which has carried several satellites all the way into orbit. The widely reported record achieved by the diminutive X-43A scramjet testbed on November 16, 2004 of nearly Mach 10 (10,621 km/h or 2.95 km/s) at 95,000 ft (29 km) is only a record for an air-breathing jet engine.
Text : Wikipedia, the free encyclopedia
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The X-15 and Hypersonics
The 1950s was definitely the decade of speed as far as U.S. aeronautical research was concerned the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA) were convinced that the key to dominating the skies was to fly faster than the opponent. The X-1 experimental aircraft broke the sound barrier in 1947. The Navy D-558-II ("D-558 Dash Two") reached Mach 2 on November 20, 1953. Soon other aircraft were reaching Mach 2.44 (1,650 miles per hour, or 2,655 kilometers per hour) and Mach 3.196 (2,094 miles per hour, or 3,370 kilometers per hour). These high speeds presented new challenges to aircraft designers.
People who study how air moves around an aircraft are called aerodynamicists. Although one of their most useful tools for decades was the wind tunnel, they could not always provide the kind of data that they needed. By the 1950s, there was virtually no way to simulate with a wind tunnel how air flowed around an aircraft at many times the speed of sound. Aerodynamicists had theoretical models (in this case a "model" is a set of equations that predict how certain shapes will act at certain airspeeds), but in order to confirm the models, they would have to actually fly an aircraft at that speed.
In 1952, the NACA established a goal of conducting research on aircraft capable of flying at speeds between Mach 4 and Mach 10 and at altitudes between 12 and 50 miles (19 and 80 kilometers). This speed range was called "hypersonic." On September 30, 1955, North American Aviation was awarded a contract to develop an aircraft to conduct this research. The aircraft was designated the X-15. The X-15 developed numerous technologies associated with high-speed flight. These technologies were later incorporated into aviation, missile, and space programs. Of all the X-plane programs (and there have been dozens), the X-15 is generally considered the most successful because it flew the longest and greatly expanded the boundaries of flight research.
The X-15 had a long fuselage with short stubby wings and an unusual tail configuration. A Reaction Motors, Inc. XLR99 rocket engine generating 57,000 pounds (253,549 newtons) of thrust powered the aircraft. This engine used ammonia and liquid oxygen for propellant and hydrogen peroxide to drive the high-speed turbopump that pumped fuel into the engine. This rocket could be throttled like an airplane engine and was the first such throttleable engine that was "man-rated" or declared safe to operate with a human aboard.
Because the X-15 would operate in extremely thin air at high altitudes, conventional mechanisms for controlling the aircraft were not sufficient, and the aircraft was equipped with small rocket engines in its nose for steering. This was the first aircraft to use such a steering method, although it was also in development for the Mercury spacecraft at the same time. The X-15 designers anticipated that their biggest problem would be the intense heat that the aircraft would encounter due to the friction of air over its skin. The upper fuselage would reach temperatures over 460 degrees Fahrenheit (F) (238 degrees Celsius [C]). But other parts of the aircraft would reach temperatures of a whopping 1,230 degrees F (666 degrees C) and the nose would reach a temperature of 1,240 degrees F (671 degrees C). Designers chose to use a high-temperature alloy known as Inconel X, which unlike most materials, remained strong at high temperatures. It was a difficult material to work with. The wings of the X-15 were constructed of Inconel X skins over titanium frames and were bolted to the fuselage instead of being mounted to a main spar as was customary.
The X-15 first flew on June 8, 1959, on a glide flight. It was dropped from under the wing of a specially modified B-52 "mothership." The first powered flight took place on September 17. Once the X-15 fell clear of the B-52, pilot Scott Crossfield ignited the rocket engine and flew to a relatively pokey Mach .79. But the X-15 was soon traveling many times the speed of sound. The X-15 continued flying until October 24, 1968, making 199 total flights among three aircraft and establishing many records.
During its early years of flight, the X-15 confirmed the hypersonic models developed by U.S. aerodynamicists. These models were later used to design other missiles and spacecraft, such as the Space Shuttle. Because of its ability to reach such high speeds and altitudes, the X-15 was a useful test platform for other research experiments. After its initial test flights it began carrying micrometeorite collection pods and ablative heat shield samples for the Apollo program and various other experiments. For approximately the last six years of its operation, the X-15 was not really conducting the missions of an X-plane (expanding the frontiers of flight), but was supporting all kinds of technology programs that required its high speed.
The X-15 pioneered the use of various materials for high-speed aircraft and spacecraft, as well as the techniques to construct them. Its rocket engine was also important for the development of later rocket engines, such as the Space Shuttle Main Engine. Inconel X was used for some key parts of the Space Shuttle structure.
The X-15 was also the first aircraft to make extensive use of a "man-in-loop" simulator to explore how the aircraft would perform in flight. A pilot would sit in the simulator on the ground and practice his procedures and try to determine what the plane would do when he later flew it. This was a new use for simulators and is now common in all experimental programs. Today, long before an aircraft begins flying, pilots and engineers are using simulators to evaluate its flying characteristics on the ground.
The X-15 is widely considered by many aerospace engineers to be the most successful experimental aircraft ever built. Of the two remaining X-15s, one is in the National Air and Space Museum in Washington, D.C., and the other is in the Air Force Museum in Dayton, Ohio.
Text by: Dwayne A. Day
And these, from owensarchive.com:
High-altitude contrails frame the B-52 mothership as it carries the X-15 aloft for a research flight on 13 April 1960 on Air Force Maj. Robert M. White's first X-15 flight. The X-15s were air-launched so that they would have enough rocket fuel to reach their high speed and altitude test points. For this early research flight, the X-15 was equipped with a pair of XLR-11 rocket engines until the XLR-99 was available.
NASA B-52, Tail Number 008, is an air launch carrier aircraft, "mothership," as well as a research aircraft platform that has been used on a variety of research projects. The aircraft, a "B" model built in 1952 and first flown on June 11, 1955, is the oldest B-52 in flying status and has been used on some of the most significant research projects in aerospace history.
X-15 (56-6672) research aircraft is secured by ground crew after landing on Rogers Dry Lakebed. The work of the X-15 team did not end with the landing of the aircraft. Once it had stopped on the lakebed, the pilot had to complete an extensive post-landing checklist.
Post-landing checklist involved recording instrument readings, pressures and temperatures, positioning switches, and shutting down systems. The pilot was then assisted from the aircraft, and a small ground crew depressurized the tanks before the rest of the ground crew finished their work on the aircraft.
Hangar 4802 at the NASA Flight Research Center in 1966. Aircraft on left include (left to right): HL-10, M2-F2, M2-F1, F-4A, F5D-1, F-104 (barely visible) and C-47. Aircraft on the right side (left to right) include: X-15-1 (56-6670), X-15-3 (56-6672), and X-15-2 (56-6671).
Hangar 4802 had been the main hangar at the Flight Research Center (FRC--now the Dryden Flight Research Center, Edwards, CA) and before that, the High-Speed Flight Station, since 1954. During 1966, the two main flight research projects at the FRC were the lifting bodies (including the M2-F1, M2-F2, and HL-10) and the X-15.
Both the HL-10 and X-15 shown here parked beside one another on the NASA ramp in 1966, underwent modifications. The X-15 No. 2 had been damaged in a crash landing in November 1962. Subsequently, the fuselage was lengthened, and it was outfitted with two large drop tanks. These modifications allowed the X-15A-2 to reach the speed of Mach 6.7.
On the HL-10, the stability problems that appeared on the first flight at the end of 1966 required a reshaping of the fins' leading edges to eliminate the separated airflow that was causing the unstable flight. By cambering the leading edges of the fins, the HL-10 team achieved attached flow and stable flight.
This photo shows one of the four attempts NASA made launching two X-15 aircraft in one day. This attempt occurred November 4, 1960. None of the four attempts was successful, although one of the two aircraft involved in each attempt usually made a research flight. In this case, Air Force pilot Robert A. Rushworth flew X-15 #1 on its 16th flight to a speed of Mach 1.95 and an altitude of 48,900 feet.
NASA research pilot Bill Dana is seen here next to the X-15 #3 rocket-powered aircraft after a flight. William H. Dana is Chief Engineer at NASA's Dryden Flight Research Center, Edwards, California.
Formerly an aerospace research pilot at Dryden, Dana flew the F-15 HIDEC research aircraft and the Advanced Fighter Technology Integration F-16 aircraft. Dana flew the X-15 research airplane 16 times, reaching a top speed of 3,897 miles per hour and a peak altitude of 310,000 feet (almost 59 miles high).
Captain Joe Engle is seen here next to the X-15-2 (56-6671) rocket-powered research aircraft after a flight. Engle made 16 flights in the X-15 between October 7, 1963, and October 14, 1965. Three of the flights, on June 29, August 10, and October 14, 1965, were above 50 miles, qualifying him for astronaut wings under the Air Force definition. (NASA followed the international definition of space as starting at 62 miles.)
Engle was selected as a NASA astronaut in 1966, making him the only person who had flown in space before being selected as an astronaut. First assigned to the Apollo program, he served on the support crew for Apollo 10, and then as backup lunar module pilot for Apollo 14. In 1977, he was commander of one of two crews who were launched from atop a modified Boeing 747 in order to conduct approach and landing tests with the Space Shuttle Enterprise.
NASA research pilot Milt Thompson stands next to the X-15 #3 ship after a research flight. Milton 0. Thompson was a research pilot, Chief Engineer and Director of Research Projects during a long career at the NASA Dryden Flight Research Center.
Thompson was hired as an engineer at the Flight Research Facility on March 19, 1956, when it was still under the auspices of NACA. He became a research pilot on May 25, 1958.
Thompson was one of the 12 NASA, Air Force, and Navy pilots to fly the X-15 rocket-powered research aircraft between 1959 and 1968. He began flying X-15s on October 29, 1963. He flew the aircraft 14 times during the following two years, reaching a maximum speed of 3723 mph (Mach 5.42) and a peak altitude of 214,100 feet on separate flights.
X-15 aircraft in flight over the desert December 20, 1961. Ship #3 made 65 flights during the program, attaining a top speed of Mach 5.65 and a maximum altitude of 354,200 feet. Only 10 of the 12 X-15 pilots flew Ship #3, and only eight of them earned their astronaut wings during the program.
Robert White, Joseph Walker, Robert Rushworth, John "Jack" McKay, Joseph Engle, William "Pete" Knight, William Dana, and Michael Adams all earned their astronaut wings in Ship #3. Neil Armstrong and Milton Thompson also flew Ship #3. In fact, Armstrong piloted Ship #3 on its first flight, on 20 December 1961
NASA test pilot Neil Armstrong wearing space suit is seen here next to the X-15 ship #1 (56-6670) after a high speed research flight. Neil A. Armstrong joined the National Advisory Committee for Aeronautics (NACA) at the Lewis Flight Propulsion Laboratory (later NASA’s Lewis Research Center, Cleveland, Ohio, and today the Glenn Research Center) in 1955.
Later that year, he transferred to the NACA’s High-Speed Flight Station (today, NASA’s Dryden Flight Research Center) at Edwards Air Force Base in California as an aeronautical research scientist and then as a pilot, a position he held until becoming an astronaut in 1962.
Armstrong was one of nine NASA astronauts in the second class to be chosen, as a research pilot he served as project pilot on the F-100A and F-100C aircraft, F-101, and the F-104A. He also flew the X-1B, X-5, F-105, F-106, B-47, KC-135, and Paresev.
Neil Armstrong left Dryden with a total of over 2450 flying hours. He was a member of the USAF-NASA Dyna-Soar Pilot Consultant Group before the Dyna-Soar project was cancelled, and studied X-20 Dyna-Soar approaches and abort maneuvers through use of the F-102A and F5D jet aircraft.
NASA research pilot Bill Dana is seen here wearing space suit, next to the X-15 rocket-powered aircraft after flight. William H. Dana is Chief Engineer at NASA's Dryden Flight Research Center, Edwards Air Force Base.
Formerly an aerospace research pilot at Dryden, Dana flew the F-15 HIDEC research aircraft and the Advanced Fighter Technology Integration/F-16 aircraft. Dana flew the X-15 research airplane 16 times, reaching a top speed of 3,897 miles per hour and a peak altitude of 310,000 feet (almost 59 miles high).
NASA X-15 test pilots, left to right; Air Force Captain Joseph H. Engle, Air Force Major Robert A. Rushworth, NASA pilot John B. "Jack" McKay, Air Force pilot William J. "Pete" Knight, NASA pilot Milton O. Thompson, and NASA pilot Bill Dana.
Of their 125 X-15 flights, 8 were above the 50 miles that constituted the Air Force's definition of the beginning of space "Engle 3, Dana 2, Rushworth, Knight, and McKay one each." NASA used the international definition of space as beginning at 62 miles above the earth. Color photograph.
This photo shows the X-15 cockpit and was unique for many reasons, including the fact that it had two types of controls for the pilot.
For flight in the dense air of the usable atmosphere, the X-15 used conventional aerodynamic controls such as rudder surfaces on the vertical stabilizers to control yaw and movable horizontal stabilizers to control pitch when moving in synchronization or roll when moved differentially.
For flight in the thin air outside of the appreciable Earth's atmosphere, the X-15 used a reaction control system. Hydrogen peroxide thrust rockets located on the nose of the aircraft provided pitch and yaw control. Those on the wing provided roll control.
The conventional aerodynamic controls used a stick, located in the middle of the floor, and pedals. The reaction control system used a side arm controller, seen in this photo on the left.
X-15 #2 (56-6671) launches away from the B-52 mothership with its rocket engine ignited. The white patches near the middle of the ship are frost from the liquid oxygen used in the propulsion system, although very cold liquid nitrogen was also used to cool the payload bay, cockpit, windshields and nose.
The X-15-1(56-6670) rocket powered research aircraft as it was rolled out in 1958. At this time, the XLR-99 rocket engine was not ready, so to make the low-speed flights (below Mach 3), the X-15 team fitted a pair of XLR-11engines into the modified rear fuselage. These were basically the same engines used in the X-1 aircraft.
The second X-15 rocket plane (56-6671) is shown with two external fuel tanks which were added during its conversion to the X-15A-2 configuration in the mid-1960's. After receiving an ablative coating to protect the craft from the high temperatures associated with high-Mach-number supersonic flight, the X-15A-2 was then covered with a white sealant coat. NASA Dryden Flight Research Center, Edwards AFB, 1965.
NASA Test pilot Major Robert M. White is seen here next to the X-15 aircraft after a research flight. White was one of the initial pilots selected for the X-15 program, representing the Air Force in the joint program with NASA, the Navy, and North American Aviation.
Between 13 April 1960 and 14 December 1962, he made 16 flights in the rocket-powered aircraft. He was the first pilot to fly to Mach 4, 5, and 6 (respectively 4, 5, and 6 times the speed of sound). He also flew to the altitude of 314,750 feet on 17 July 1962, setting a world altitude record.
This was 59.6 miles, significantly higher than the 50 miles the Air Force accepted as the beginning of space, qualifying White for astronaut wings.
Air Force test pilot William J. "Pete" Knight is seen here in front of the X-15A-2 aircraft (56-6671). Pete Knight made 16 flights in the X-15, and set the world unofficial speed record for fixed wing aircraft, 4,520 mph (mach 6.7), in the X-15A-2. He also made one flight above 50 miles, qualifying him for astronaut wings.
The X-15 rocket-powered aircraft was taken aloft under the wing of a B-52. Because of the large fuel consumption, the X-15 was air launched from a B-52 mothership aircraft at 45,000 ft and a speed of about 500 mph. This was one of the early powered flights using a pair of XLR-11 engines (until the XLR-99 became available).
After receiving a full scale ablative coating to protect the craft from the high temperatures associated with high-Mach-number supersonic flight, the X-15A-2 (56-6671) rocket powered research aircraft was then covered with a white sealant coat and mounted with additional external fuel tanks. This ablative coating and sealant would help the X-15A-2 aircraft reach the record speed of 4,520 mph (Mach 6.7).
X-15 rocket powered aircraft was taken aloft under the wing of a B-52. Because of the large fuel consumption, the X-15 was air launched from a B-52 aircraft at 45,000 ft and a speed of about 500 mph. This photo was taken from one of the observation windows in the B-52 shortly before dropping the X-15.
North American Aviation X-15 followed by a Lockheed F-104A Starfighter chase plane, the North American X-15 ship #3 (56-6672) sinks toward touchdown on Rogers Dry Lake following a research flight. In the foreground is green smoke, used to indicate wind direction.
The F-104 chase pilot joined up with the X-15 as it glided to the landing. The chase pilot was there to warn the X-15 pilot of any problems and to call out the altitude above the lakebed. F-104 aircraft were also used for X-15 pilot training to simulate the landing characteristics of the rocket-powered airplane, which landed without engine power since the rocket engine had already burned all of its propellant before the landing.
The F-104s could simulate the steep descent of the X-15 as it glided to a landing, they did this by extending the landing gear and speed brakes while setting the throttle to idle.
The X-15 ship #3 (56-6672) is seen here on the lakebed at the Edwards Air Force Base, Edwards, California. Ship #3 made 65 flights during the program, attaining a top speed of Mach 5.65 and a maximum altitude of 354,200 feet.
Only 10 of the 12 X-15 pilots flew Ship #3, and only eight of them earned their astronaut wings during the program. Robert White, Joseph Walker, Robert Rushworth, John "Jack" McKay, Joseph Engle, William "Pete" Knight, William Dana, and Michael Adams all earned their astronaut wings in Ship #3. Neil Armstrong and Milton Thompson also flew Ship #3. In fact, Armstrong piloted Ship #3 on its first flight, on 20 December 1961
The X-15-3 (56-6672), seen here on the lakebed at Edwards Air Force Base, Edwards, California, was a rocket-powered aircraft 50 ft long with a wingspan of 22 ft. It was a missile-shaped vehicle with an unusual wedge-shaped vertical tail, thin stubby wings, and unique side fairings that extended along the side of the fuselage.
The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch. The XLR-99 rocket engine, manufactured by Thiokol Chemical Corp., was pilot controlled and was capable of developing 57,000 lb of thrust. North American Aviation built three X-15 aircraft for the program.
On 9 November 1962, an engine failure forced Jack McKay, a NASA research pilot, to make an emergency landing at Mud Lake, Nevada, in the second X-15 (56-6671); its landing gear collapsed and the X-15 flipped over on its back. McKay was promptly rescued by an Air Force medical team standing by near the launch site, and eventually recovered to fly the X-15 again.
Test pilot Jack McKay injuries were more serious than at first thought, eventually forced his retirement from NASA. The aircraft was sent back to the manufacturer, where it underwent extensive repairs and modifications. It returned to Edwards in February 1964 as the X-15A-2, with a longer fuselage (52 ft 5 in) and external fuel tanks.
A series of ground and in-flight accidents occurred during the X-15's contractor program, fortunately without injuries or even greatly delaying the program. On 5 November 1959 a small engine fire started and forced pilot Scott Crossfield to make an emergency landing on Rosamond Dry Lake.
The X-15, not designed to land with fuel, came down with a heavy load of propellants and broke its back, grounding this particular X-15, ship #2 (56-6671), for three months.
This photo shows the X-15A-2 (56-6671) on a research flight with a ramjet engine attached to the bottom of its wedge-shaped vertical tail.
One of the experiments planned for the X-15A-2 involved tests of a functional ramjet at speeds above Mach 5. This photo was taken with a dummy ramjet. On this research flight, the X-15A-2 did not carry the two drop tanks used on its Mach 6.7 flight. It also had not yet been covered with an ablative coating.
The X-15A-2 made several flights with the dummy ramjet, leading to the record Mach 6.7 flight on October 3, 1967. Delays in producing the operational ramjet, aerodynamic heating damage to the aircraft during the record flight (despite the ablative coating), and the end of the X-15 program in 1968 resulted in no flights with the actual ramjet.
The X-15 aircraft, ship #1 (56-6670), sits on the lakebed early in its illustrious career of high speed flight research. The X-15 was a rocket-powered aircraft 50 ft long with a wingspan of 22 ft. It was a missile-shaped vehicle with an unusual wedge-shaped vertical tail, thin stubby wings, and unique side fairings that extended along the side of the fuselage. The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch.
X-15 test pilots, left to right; Air Force Captain Joseph H. Engle, Air Force Major Robert A. Rushworth, NASA pilot John B. "Jack" McKay, Air Force pilot William J. "Pete" Knight, NASA pilot Milton O. Thompson, and NASA pilot Bill Dana.
Of their 125 X-15 flights, 8 were above the 50 miles that constituted the Air Force's definition of the beginning of space "Engle 3, Dana 2, Rushworth, Knight, and McKay one each." NASA used the international definition of space as beginning at 62 miles above the earth.
NASA test pilots Milton O. Thompson, William H. "Bill" Dana, and John B. "Jack" McKay are seen here in front of the #2 X-15 (56-6671) rocket-powered research aircraft. Among them, the three NASA research test pilots made 59 flights in the X-15 (14 for Thompson, 16 for Dana, and 29 for McKay).
X-15 rocket-powered research aircraft being carried aloft under the wing of its B-52 mothership. The X-15 was air launched from the B-52 so the rocket plane would have enough fuel to reach its high speed and altitude test points.
NASA B-52, Tail Number 008, is an air launch carrier aircraft, "mothership," as well as a research aircraft platform that has been used on a variety of research projects. The aircraft, a "B" model built in 1952 and first flown on June 11, 1955, is the oldest B-52 in flying status and has been used on some of the most significant research projects in aerospace history.
The X-15 (56-6670), seen here on the lakebed at Edwards Air Force Base, Edwards, California. This X-15 was still equipped with two XLR-11 engines designed and built by Reaction Motors, pending installation of the XLR-99 engine, which first flew on November 15, 1960.
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About the X-15B:
From astronautix.com:
American manned spacecraft. Study 1958. North American's proposal for the Air Force initial manned space project was to extend the X-15 program. The X-15B was a 'stripped' X-15A with an empty mass of 4500 kg.
It would use a three-stage Navaho-derived launch vehicle to achieve a single orbit with an apogee of 120 km and a perigee of 75 km.
In the aftermath of Sputnik 2, the Air Force quietly asked its leading contractors for "unsolicited" proposals for manned spacecraft that could be quickly executed and beat the Russians in putting a man in orbit. Harrison Storms of North American conceived of a bold move to get an American into space as quickly as possible, in order to beat the Russians in the next obvious step of the space race. North American had a warehouse full of partially-completed G-38 boosters for the just-canceled Navaho missile program. Storms threw together a proposal to cluster them four of them in order to launch an orbital version of the company's X-15 manned rocketplane. He took the proposal to the Air Research and Development Command (ARDC) at Wright Field in November 1957.
Storms' X-15B was a 'stripped' X-15A with an empty mass of 4500 kg. The launch vehicle consisted of 4 x G-26 Navaho booster stages plus the X-15B's own XLR-99 engine. These would allow the X-15B to achieve a single orbit with an apogee of 120 km and a perigee of 75 km. Due to the low perigee and aerodynamics of the X-15, no retrorocket was required, although the X-15's restartable engine could be used if necessary. Using its cross range capability of about 800 to 1,000 km, the X-15 would ditch in the Gulf of Mexico. The heat shield would consist of beryllium oxide and Rene 41 alloy. The pilot would eject and land by parachute, with the aircraft being lost. The spacecraft had a ballistic coefficient (W/CdA) of 250 kg per square meter. It was expected that a first manned orbital flight could be achieved 30 months after a go-ahead at a cost of $ 120 million.
The general in charge of ARDC found it interesting but said there was no official requirement to orbit a man in space. But the political pressure to do something in response to Sputnik mounted, and a secret conference was held at on 29-31 January 1958 at Wright field. Eleven aircraft and missile firms outlined for the Air Force and NACA observers the various classified proposals for a manned satellite vehicle that they had submitted during November and December 1957.
The ARDC boiled down the 11 proposals to the three that had the best chance of quick realization - the X-15B, acceleration of the nascent program for the X-20 Dynasoar winged space glider, or one of the simple ballistic capsule designs, boosted by an existing launch vehicle. On 27 February they took these straight to Curtis LeMay, head of the Strategic Air Command, who's main comment was, "Where's the bomb bay?" Nevertheless, he instructed ARDC to select one of the concepts and submit a detailed plan for an Air Force man-in-space program as soon as possible.
On 10-12 March ARDC held a conference at its Ballistic Missile Division (BMD) in Los Angeles of more than 80 rocket, aircraft, and human-factors specialists. The objective was to reach agreement on a plan to get a man-in-space - soonest - in accordance with LeMay's orders. The BMD itself had its sights set on Project Lunex, a long term plan to establish an Air Force base on the moon before 1970. Unfortunately for Storms, the consensus at the conference was that the "quick and dirty" approach would consist of a simple ballistic capsule using parachutes for a water landing, weighing around 1300 kg. This would be 1.8 m in diameter and 2.4 m long. The capsule would be completely automated - the human-factors people felt there was no certainty that a pilot could function under the stresses of space flight. This last point seemed to rule out the piloted X-15B approach.
ARDC continued on the Manned-in-Space-Soonest project into August 1958, and in June Storms had even been told he would receive the contract for the manned spacecraft. But meanwhile, President Eisenhower and the Congress had created a new civilian Agency to take on the Soviet spaceflight challenge - NASA. And Max Faget, the lead spacecraft designer at NASA, was one of the originators of the ballistic capsule concept. The USAF budget for the initial manned spacecraft was transferred to NASA, and with it evaporated Storms' expected contract, and the X-15B. The contract for what NASA renamed project Mercury would go to McDonnell.
This was not quite the end of the orbital X-15. It was known that North American later proposed use of four Titan I booster stages in place of the Navaho boosters.
Note
The notes of NACA engineer Clarence A. Syvertson from this meeting indicate that four Navaho G-26 boosters would be used. The biography of Harrison Storms indicates that G-38 boosters were proposed. A quick calculation showed that four G-26 boosters could not get the X-15 into orbit; G-38 boosters just about could. So in this case physics and the memory of Storms trump the contemporaneous notes. It was likely in any case that the boosters proposed were derived from, but not identical to the G-26 or G-38 boosters.
A drawing also emerged of an X-15 atop a single G-26 booster. It was likely that a program of slow build-up to orbital speeds, using Navaho surplus assets, was proposed.
Characteristics
Crew Size: 1. Spacecraft delta v: 2,450 m/s (8,030 ft/sec).
Gross mass: 13,500 kg (29,700 lb).
Unfuelled mass: 4,500 kg (9,900 lb).
Height: 15.00 m (49.00 ft).
Span: 6.80 m (22.30 ft).
Thrust: 262.45 kN (59,000 lbf).
Specific impulse: 276 s.
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Associated Countries •USA
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Associated Engines •XLR99 Thiokol Lox/Ammonia rocket engine. 262.4 kN. Out of production. Isp=276s. The first large, man-rated, throttleable, restartable liquid propellant rocket engine, boosted the X-15A. First flight 1959. More...
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See also •Low earth orbit
•Man-In-Space-Soonest The beginning of the Air Force's Man-In-Space-Soonest program has been traced back to a staff meeting of General Thomas S Power, Commander of the Air Research and Development Command (ARDC) in Baltimore on 15 February 1956. Power wanted studies to begin on manned space vehicles that would follow the X-15 rocketplane. These were to include winged and ballistic approaches - the ballistic rocket was seen as being a militarily useful intercontinental troop and cargo vehicle. More...
•Manned
•Manned spacecraft
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Associated Manufacturers and Agencies •USAF American agency overseeing development of rockets and spacecraft. United States Air Force, USA. More...
•North American American manufacturer of rockets, spacecraft, and rocket engines. North American, Palmdale, El Segundo. Downey, CA, USA More...
•USAF American agency. USAF, USA. More...
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Associated Propellants •Lox/Ammonia
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Bibliography •Baker, David, The History of Manned Spaceflight, Crown, New York, 1981.
•Jenkins, Dennis R,, Space Shuttle: The History of the National Space Transportation System : The First 100 Missions, Third edition, Voyageur Press, 2001.
•Swenson, Grimwood, Alexander, Charles C, This New Ocean, Government Printing Office, 1966. Web Address when accessed: http://www.hq.nasa.gov/office/pao/History/SP-4201/cover.htm.
•Grimwood, James M., Project Mercury: A Chronology, NASA Special Publication-4001.
•Gray, Mike, Angle of Attack: Harrison Storms and the Race to the Moon, Penguin Reprint edition, 1994.
More, from friends-partners.org.:
X-15B - Orbital X-15 proposed for Project 7969
Credit: (c) Mark Wade. 9,079 bytes. 211 x 480 pixels.
X-15B
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Class: Manned. Type: Spacecraft. Nation: USA. Agency: USAF. Manufacturer: North American.
North American's proposal for the Air Force initial manned space project was to extend the X-15 program. The X-15B was a 'stripped' X-15A with an empty mass of 4500 kg. It would use a three-stage Navaho-derived launch vehicle to achieve a single orbit with an apogee of 120 km and a perigee of 75 km. The launch vehicle consisted of 4 x G-26 Navaho booster stages plus the X-15B's own XLR-99 engine. Due to the low perigee and aerodynamics of the X-15, no retrorocket was required, although the X-15's restartable engine could be used if necessary. Using its cross range capability of about 800 to 1,000 km, the X-15 would ditch in the Gulf of Mexico. The heat shield would consist of beryllium oxide and Rene 41 alloy. The pilot would eject and land by parachute, with the aircraft being lost. The spacecraft had a ballistic coefficient (W/CdA) of 250 kg per square meter. It was expected that a first manned orbital flight could be achieved 30 months after a go-ahead at a cost of $ 120 million.
And this:
X-15B: pursuit of early orbital human spaceflight.
[ILLUSTRATION OMITTED]
The North American X-15 hypersonic research aircraft was among the most successful of all the X-series. A cooperative research program among the U.S. Navy, Air Force and the National Aeronautics and Space Administration (NASA), the X-15 exceeded all expectations as it expanded the known flight envelope. When the program ended after 199 flights, the U.S. was well along the path towards operational space vehicles and human spaceflight.
An orbital version, variously called the Advanced X-15, Orbital X-15, or X-15B, began in part with the original proposals for the X-15 calling for a two-seat version. The concept endured at a low level for several years, reaching a peak of interest in 1958-1959. When mentioned at all subsequently, the X-15B has been relegated to little more than a footnote, and understood as the logical progression for much of the X-series aircraft pushing higher, faster and farther. (1)
Justifying the X-15B as simply pushing the flight envelope outwards is as misleading as making the same argument for MERCURY. Higher, faster and farther might be felt as an imperative or a characterization of aviation's evolution, but it was not the end in itself. The orbital X-15 answered very different motivations.
The Role of Human Presence--1950s Style
The U.S. space program began in the military long before NASA's 1958 creation. The military developed the sine qua non of any space program: the launch vehicles. The military also had all the plans, concepts and strategies receiving any funding (however meager) in the early 1950s. "Artificial moons" were so radical that many of the senior military leadership only vaguely understood them. Especially in the Air Force, experience with robotic aircraft colored any understanding of robotic spacecraft.
Tenuous attempts in World War II using robotic (now called unpiloted) aircraft showed serious limitations. Lessons learned from these attempts exposed the real bias: human presence caused operational utility. This remained the military consensus for decades after World War II. Robotic aircraft of the 1950s, such as the SNARK, REGULUS, MATADOR and MACE, were akin to but far less capable than today's cruise missiles. All suffered from rudimentary technology inadequate to the senior military leadership demands for effective and reliable weapons. Progress was erratic. These early programs indicated to the military leadership that they held some interesting ideas, but were hardly reliable or operational.
On October 5, 1954, the National Advisory Committee on Aeronautics' (NACA) High-Speed Flight Station executive committee faced the final decision to proceed with a hypersonic research aircraft. Lockheed's Clarence "Kelly" Johnson alone favored robotic aircraft to explore the flight regimes proposed for the X-15. He firmly...
Read more: http://vlex.com/vid/x-15b-pursuit-early-orbital-spaceflight-56379293#ixzz1OBKpka6W
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Specification
Total Mass: 4,500 kg.
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Bibliography:
26 - Baker, David, The History of Manned Spaceflight, Crown, New York, 1981.
483 - Grimwood, James M., Project Mercury: A Chronology, NASA Special Publication-4001.
And lastly, this, from findarticles.com:
X-15B: pursuit of early orbital human spaceflight
by L. Parker Temple, III
The North American X-15 hypersonic research aircraft was among the most successful of all the X-series. A cooperative research program among the U.S. Navy, Air Force and the National Aeronautics and Space Administration (NASA), the X-15 exceeded all expectations as it expanded the known flight envelope. When the program ended after 199 flights, the U.S. was well along the path towards operational space vehicles and human spaceflight.
An orbital version, variously called the Advanced X-15, Orbital X-15, or X-15B, began in part with the original proposals for the X-15 calling for a two-seat version. The concept endured at a low level for several years, reaching a peak of interest in 1958-1959. When mentioned at all subsequently, the X-15B has been relegated to little more than a footnote, and understood as the logical progression for much of the X-series aircraft pushing higher, faster and farther. (1)
Justifying the X-15B as simply pushing the flight envelope outwards is as misleading as making the same argument for MERCURY. Higher, faster and farther might be felt as an imperative or a characterization of aviation's evolution, but it was not the end in itself. The orbital X-15 answered very different motivations.
The Role of Human Presence--1950s Style
The U.S. space program began in the military long before NASA's 1958 creation. The military developed the sine qua non of any space program: the launch vehicles. The military also had all the plans, concepts and strategies receiving any funding (however meager) in the early 1950s. "Artificial moons" were so radical that many of the senior military leadership only vaguely understood them. Especially in the Air Force, experience with robotic aircraft colored any understanding of robotic spacecraft.
Tenuous attempts in World War II using robotic (now called unpiloted) aircraft showed serious limitations. Lessons learned from these attempts exposed the real bias: human presence caused operational utility. This remained the military consensus for decades after World War II. Robotic aircraft of the 1950s, such as the SNARK, REGULUS, MATADOR and MACE, were akin to but far less capable than today's cruise missiles. All suffered from rudimentary technology inadequate to the senior military leadership demands for effective and reliable weapons. Progress was erratic. These early programs indicated to the military leadership that they held some interesting ideas, but were hardly reliable or operational.
On October 5, 1954, the National Advisory Committee on Aeronautics' (NACA) High-Speed Flight Station executive committee faced the final decision to proceed with a hypersonic research aircraft. Lockheed's Clarence "Kelly" Johnson alone favored robotic aircraft to explore the flight regimes proposed for the X-15. He firmly believed in human presence for operational (that is, practical application) missions, as opposed to purely aerodynamic research. At the time, he was developing the U-2 spyplane and thinking ahead to hydrogen-fuelled hypersonic reconnaissance aircraft. (2) Perhaps he thought a robotic aircraft could answer specific questions related to hypersonic aircraft sooner than a piloted aircraft, facilitating the development of operational aircraft he had in mind. Everyone else believed human presence was mandatory. (3) NACA's associate director for research, Gus Crowley, summed up the majority view: the successful X-1 program owed much to its pilots, whose performance allowed accomplishment of things robotic aircraft could not do. (4) This reveals the mindset that truly useful and operational capabilities required human presence.
This was the mindset, then, in the earliest days of the military's (and hence the nation's) space program. Robotic devices were so limited, based on experience with robotic aircraft, that human presence would inevitably be needed to achieve any operational military capability.
What benefits might human presence provide? A contemporary list simultaneously contrasted perceived benefits of human presence versus robotic spacecraft technological shortfalls. Since human presence counteracted robotic spacecraft shortfalls, the list was considered a standard against which to measure military space progress in the 1950s:
Decision Making Capability
Robots cannot perform "rapid and accurate decision making ... by 'on the spot' assessment of the situation."
Command Control Capability
Humans understand and react faster than robot computational speeds.
Determination of Vehicle and Payload Status
Humans monitor the spacecraft's status in situ, whereas robots require relay to the ground for processing.
Post-Launch Changes in Mission Plan
Humans perform more flexibly and readily adapt to new missions.
Payload Redundancy
Humans can "augment certain payload functions ... in the event of payload subsystem breakdowns."
Mission Data Redundancy
Remote, unobserved sensors might not report accurately; human presence can verify or deny sensors' reports.
Mission Data Augmentation
Robotic sensors are specialized with limited capacity for recording data. Humans can take inputs from many sources and integrate a complete picture of a situation.
Recovery of On-Board Payload Data
For a spaceplane, the ability to choose a landing site is crucial to returning the mission's data. Pilots routinely do this.
Early Mission Termination and Recovery
Humans can determine when to return or extend the orbit. Robots might suffer, at any time, "mission termination based on on-board programming."
Accomplishment of Mission Details
Humans can adjust sensors to "optimize the gathering of mission data."
Subsystem Complexity
Humans are "a general-purpose subsystem with a general-purpose compute capability to store and analyze events." (5)
These claims about the value of human presence reflected Air Force doctrine drawn from decades of atmospheric flying. Air Force Headquarters personnel, lacking any basis for judgment without actual human spaceflight experience, accepted these claims. Artificial moons might provide important interim capabilities, but as was the case with the robotic aircraft, only human-piloted spaceplanes had operational utility.
Clearly, the bias towards human presence that also anticipated robotic spacecraft would not be very capable was soon overturned as the U.S. devoted considerable resources and its best minds to the space program. The bias, however, is important to consider when judging the initial push for making the X-15, or any piloted vehicle, into an orbital spacecraft.
With this contemporary expectation of the value of human presence, and to really place the X-15B in context, we next need to understand the context itself: the flurry of activity surrounding spaceplanes in the mid-1950s.
Higher, Faster and Farther?
Although interest in spaceplanes was long standing, serious studies of orbital spaceplanes and high-speed rocket aircraft skimming across the upper edges of the sensible atmosphere began right after World War II. These studies extrapolated the first operational rocket planes flown by the Germans during the war. Each of the Services had some variation under study at a very low level.
For instance, the Navy received a proposal from Douglas Aircraft for a third generation of its D-558 series of research aircraft in 1953. That rocket plane, later part of the Douglas proposal for the X-15 competition, was to achieve one million feet altitude and nearly orbital speed, later scaled back to a more modest 750,000 feet and Mach 9. However, the project remained a paper study eventually yielding to the X-15. (6)
Bell Aircraft Corporation submitted a seminal proposal to Wright Air Development Center (WADC) on April 17, 1952. The premier X-series aircraft developer had hired Walther Dornberger as a rocketry consultant. The World War II commandant of Peenemunde for development and launch of the V-1 and V-2 rockets, Dornberger had been Wernher von Braun's former superior officer. He pushed for manned hypersonic rocket-launched gliders based on the pre-World War II ideas of Eugen Sanger and his wife Irene Bredt. (7)
Bell examined air launch of its X-series aircraft to achieve orbit, and proposed a new operational manned bomber-missile, BOMI. WADC offered Bell a one-year study to advance the concept, and asked for two examinations--a suborbital, hypersonic version and an orbital version. Bell combined both into a phased development from suborbital to orbital flight. A year's effort showed little progress. Dornberger's constant lobbying kept BOMI alive. By his estimate, he eventually gave some 900 presentations to all sorts of audiences on BOMI and successor spaceplanes. (8) His politicking worked, because in April 1954, Bell received another small contract to study an advanced reconnaissance bomber concept, designated MX-2276. This version of BOMI resembled the suborbital vehicle of the first phase in the original WADC study. Like its more famous successor, the DYNA-SOAR--for its suborbital (dynamic soaring) flight regime-MX-2276 was a nuclear weapon delivery system that could do its own post-strike reconnaissance.
Reconnaissance was critically important at the time. Closure of the Soviet Union's borders created a desperate need for Western intelligence about Soviet intentions. (9) President Dwight D. Eisenhower chartered a Technological Capabilities Panel to examine preventing a Soviet surprise nuclear attack. Throughout 1954, this effort identified a number of critically important steps the nation had to take. Among these were the developments of the Lockheed U-2 spyplane and the CORONA satellite reconnaissance system. These programs were covert; that is, not merely classified but hidden with their existence unacknowledged.
Meanwhile, the threat of surprise attack remained palpable, and the Services went about trying to solve the problem. On January 4, 1955, Air Research and Development Command (ARDC), anticipating the release of a General Operating Requirement (GOR) then in final coordination, released System Requirement 12 for an advanced reconnaissance aircraft with 3,000 nautical mile range and a ceiling of 100,000 feet. A month later, Air Force Headquarters released its equivalent, higher-level GOR 12, to proceed under Weapon System 118P, the Special Reconnaissance System. By September 1955, Bell's support to WS-118P included further BOMI studies. (10)
Air Force studies of a more advanced reconnaissance-bomber began in March 1956. The Hypersonic Weapon And Research and Development System (HYWARDS) was to achieve Mach 12 flight, twice that of the X-15 then on the drawing boards. (11)
Also, Bell got another contract for a highly advanced U-2 follow-on called BRASS BELL, Reconnaissance System 459L. Two months later, ARDC released System Requirement 126 for a I rocket-bomber, ROBO. ROBO allegedly included a reconnaissance version combining radar, infrared and optical scanning sensors, with relay of the sensor information to the ground while the ROBO was still in flight. (12)
Working cooperatively with NACA Langley for the aerodynamics research, the HYWARDS team soon realized that Mach 12 was insufficient, and that Mach 15 "was about the lowest speed for which an attractive military boost-glide mission could be defined." (13) From there, it seemed but a short step to Mach 18 (nearly orbital), which the group recommended in January 1957.
The plethora of spaceplanes formed a logical sequence, with HYWARDS to fly in 1965, BRASS BELL in 1968, followed by ROBO in 1974. (14) The proliferating concepts begged for consolidation. Air Force Deputy Chief of Staff (Development) Lt. Gen. Donald Putt reviewed the programs in January 1957. He thought BRASS BELL and HYWARDS were complementary and could be combined into a single, two-phase program. Furthermore, the X-15A would clearly provide nearly everything that could be learned from HYWARDS. Thus, in April 1957, Putt directed ARDC to combine all hypersonic research programs into a single development plan. (15)
NACA was also struggling with spaceplane concept diversity. For instance, NACA Ames and NACA Langley were at odds over the relative advantages of high and low lift-to-drag ratios. With only that one variable in mind, the range of studies and technologies was very large, indicating the considerable work necessary to explore various parts of the high speed flight regime. The Ames-Langley disagreements were technical, political and organizational. They serve to highlight the complexity of the issues involved in advancing spaceplanes. The range of options was simply so extensive that no single correct solution would readily reveal itself. (16)
Within this swirl in both NACA and ARDC, WADC produced a reasonable response to Putts direction for a unified development plan. HYWARDS, BRASS BELL and ROBO became three steps in an abbreviated program of development on December 21, 1957. (17) The combined effort was designated System 464L, named DYNA-SOAR I, with a projected first flight in July 1962. (18)
Strategic Air Command was the operational home for a variety of space uses, not the least of which were those embodied by DYNA-SOAR. Strategic Air Command's General Curtis E. LeMay intended DYNA-SOAR I as an advanced bomber, reconnaissance, air defense and space defense vehicle. (19) The DYNA-SOAR project elements convey a feeling for the broad range of capabilities that spaceplanes might accomplish: Manned Capsule Test; Boost-Glide Tactical Weapon Delivery; Boost-Glide Interceptor; Satellite Interceptor; Global Reconnaissance; and Global Bomber. (20)
Well aware of Putt's impending reorganization of spaceplanes, on the 54th anniversary of the first flight by the Wright Brothers, December 14, 1957, Air Force Chief of Staff General Thomas Dresser White announced "The missiles that are getting the headlines today are but one step in the evolution from aircraft to piloted spacecraft." (21)
Three days later, General White told the Senate Armed Services Committee that the X-15 "was a forerunner of the spacecraft ... [and] requires all the characteristics that one would find in a manned satellite to take care of the man." (22)
Human Orbital Spaceflight: Be First or Be Useful?
As rapidly as technology advanced, producing the first crucial operational space systems within two years of SPUTNIK (such as the CORONA, GRAB and POPPY reconnaissance satellites), the perception remained that these were really only interim capabilities awaiting routine human presence. The appropriate question, therefore, was not whether human spaceflight was needed, but rather, when it could be provided. Obviously, sooner was better than later.
By 1956, Air Force Project 7969, the Manned Ballistic Rocket Research System (23) was competing directly with the Army Ballistic Missile Agency's concept for a recoverable system on an Army missile (which became MERCURY). These bioastronautics research programs aimed at the minimum requirements to put humans in space and return them safely to Earth. These minimalist programs were not ends unto themselves, but simply necessary stepping-stones to operational missions.
The earliest design work on the X-15B dates from this period. Project 7969 was an important bridge between the minimalist and the robust, in that the proposals received from industry included both ballistic re-entry vehicles and winged vehicles. Perhaps the most interesting proposal was North American's proposal for an evolved X-15. Using staged boosters, the aircraft would orbit between 250,000 (perigee) and 400,000 feet (apogee). The first stage comprised three NAVAHO boosters; (24) another NAVAHO booster as a second stage; and the X-15B was the third. Its estimated gross liftoff weight was 720,000 pounds. Since the X-15B would have the same shape as the X-15A, nothing further was considered necessary for determining its flight characteristics. However, re-entry would only get the pilot to a safe ejection altitude, with the X-15 being lost in the Gulf of Mexico. North American's claimed cost and schedule were $120 million and 30 months. This was not very satisfactory, as it was a very expensive, one-time shot with no residual operational utility. (25) Nevertheless, the idea opened a door. After all, Putt's realization that most of HYWARDS' results could be gained from the X-15 meant that a version of the X-15 could be on a growth path to ROBO's operational mission, recently subsumed into DYNA-SOAR I. Nevertheless, making the X-15A withstand the expected re-entry heat and stress meant the X-15B would be a radically different vehicle in detail. (26)
Things stood there when the Soviets launched SPUTNIK on October 4, 1957, and the emphasis on space programs changed.
The VANGUARD project to launch an artificial moon during the International Geophysical Year, seen as the US' competitor to SPUTNIK, was far from success. The military were the only source of response to SPUTNIK. The problem was not a lack of alternatives, but choosing the right one.
As a champion for spaceplanes and a military space visionary, General LeMay, by that time the Air Force Vice Chief of Staff, took a personal interest in satellite and human spaceflight. LeMay announced the Man-In-Space-Soonest (MISS) project, causing the re-orientation of a number of ongoing studies and projects. Project 7969 got folded into MISS as one of the alternatives. (27)
Because of Project 7969's inclusion in MISS, MISS might sound like MERCURY. MERCURY began in the Army and eventually transferred to the new NASA after 1958. This was essentially the minimum system to put a human into space and safely return. Little weight or space remained for operational missions. This is not minimizing MERCURY's importance in demonstrating critical life support technologies and human spaceflight capabilities. However, MERCURY's limitations simply served to underscore the military objections to NASA's human spaceflight approach.
MISS' emphasis was on attaining operational capabilities from space at the earliest possible time. Interim steps might be needed to understand human physiology and life support systems, but the goal was operational uses. Competing ballistic reentry and lifting re-entry (spaceplane) concepts abounded, though with scanty data available for design. By 1957, Boeing's DYNA-SOAR embodied the Air Force's goal, providing a means to put military humans into space to perform militarily useful operational missions. DYNA-SOAR's urgently needed capabilities were a long way off, with its expected first flight in 1962. (28)
To grasp the range of alternatives, aside from the Air Force's own concepts, WADC held government-industry meetings January 29-31, 1958. In addition to discussing NACA projects, the Air Force invited 11 major contractors for an hour and a half apiece to brief concepts for achieving early human spaceflight. (29)
NACA Langley discussed Max Faget's research on a ballistic vehicle (basically the MERCURY capsule) and John V. Becker described work being done on a triangular planform that would use lift during re-entry to provide great flexibility in landing sites. After these informal discussions, the serious work got underway with the contractors. The final presentation was from North American Aviation, who described turning the X-15 aeronautical research aircraft into an operational (non-expendable) spaceplane. (30)
The MISS project alternatives grouped into three basic categories: ballistic vehicles, boost-glide vehicles and satelloids. Ballistic vehicles were shapes like ballistic missile nose cones intended to survive re-entry. The boost-glide vehicles would achieve nearly the same velocity, but would skim the upper reaches of the atmosphere as gliders at lower altitudes. Satelloids were basically gliders that would achieve minimum orbital velocity well above the atmosphere and use their aerodynamic features for re-entry. (31)
In February 1958, LeMay reviewed the alternative paths from the WADC conference. For the most part, the ballistic re-entry idea was the most competitive if the goal were limited to getting into space for no other point than having gotten there. That remained operationally unsatisfying because it could not be tied to some useful purpose. The Army's MERCURY capsule was one ballistic approach having no residual operational utility, but the Air Force had an alternative with an operational tie-in.
The SAMOS E-6 photoreconnaissance satellite required a very large re-entry capsule because both the film and the camera were to be recovered for reuse. (32) Unlike the blunt re-entry capsule of the familiar MERCURY design, the SAMOS capsule used a scaled-up General Electric RVX-2 missile re-entry nose cone. (33) Like CORONA, the SAMOS E-6 needed a plausible explanation for its launches. CORONA's cover story was the DISCOVERER research program. SAMOS used human spaceflight to explain the large size of its vehicles. Like MERCURY, the scaled-up RVX-2 was minimally large enough to fit a human inside, and was one alternative under Project 7969. (34) Also, the MISS version of the SAMOS capsule had little residual operational capability. In the case of SAMOS, however, the MISS version was secondary cover for an operational photoreconnaissance system. Since the human spaceflight story protected a classified mission, losing human spaceflight programs to NASA jeopardized the more important mission. Thus, in part, the Air Force objected, in support of the Army, to assigning human spaceflight responsibility to NASA. (35)
Such wingless, ballistic shapes had the advantage of simplicity, but serious disadvantages if anything other than basic bioastronautics was the goal. Bell's MISS boost-glide alternative design team pointed out that "wingless would only be a stunt." (36)
The second alternative path comprised boost-glide vehicles, including LeMay's favorite, DYNA-SOAR, undergoing initial source selection at that time.
Satelloid vehicles constituted the third alternative path, and included the X-15 that already had the first functional fu]l pressure space suit and flew at the edge of space. The X-15A program performed experiments inspired by the need for early DYNA-SOAR technology work. The X-15A was an ideal testbed for X-20 technology, but it also provided an apparent path to an earlier, though more limited, orbital capability. Making an orbital X-15 variant might be the fastest way to get real operational capability, while also resolving much of the flurry of proliferated spaceplane concepts. With an estimated much shorter (by half) development time than the boost-glide vehicles, the X-15B could also demonstrate critical technologies for DYNA-SOAR. (37)
While all three alternatives continued to move forward, each having merit for different reasons, the heat shortly got turned up on the ballistic reentry approach.
In April 1958, Maj. Gen. John B. Medaris, commander of the Army Ballistic Missile Agency, told Congress that he had recently asked for authority to launch a human on a JUPITER-C rocket and return him to Earth. He and Wernher von Braun claimed they could do this a year after direction to proceed. The Army and, after the concept's transfer to the new civilian space agency, NASA called it MERCURY. (38,39)
MERCURY was the fastest way to get humans into space and safely return them. Nearly as quickly, though, the X-15 might do far more in terms of residual capabilities. The MISS participants had all estimated between one and two and a half years to get a human into space and safely return (with two notable exceptions, whose estimates were more realistic at 5 years). Ballistic reentry shapes had the shortest development times. (40)
Nevertheless, the X-15 was designed to fly at the edge of the atmosphere at about one quarter of orbital speed. It already had to handle many of the physiological problems associated with orbital flight. The X-15 had shown it could handle sub-orbital flight, demonstrating its advanced capabilities on a regular basis. Orbital flight demanded long duration in space, so the X-15's life support system needed significant upgrading. Neither was its structure sufficiently durable to dissipate the heat of re-entry. Still, in theory, transforming the technologically mature X-15 into an operationally useful orbital spaceplane might be faster than any alternative.
Yet, by late 1957, interest in the orbital X-15B apparently evaporated, according to the sources that even discuss its existence. Hallion suggested that the MERCURY program overtook the orbital X-15B. However, MERCURY could not overcome its absence of residual operational utility. Jenkins claimed the X-15B drifted quietly away. (41) He assumed DYNA-SOAR (which became the X-20 in 1958) required too much attention by the Air Force for serious attention to be paid to the X-15B. Neither answer is entirely satisfactory.
What was the reality?
Instead of drifting quietly away, the X-15B studies became classified in 1957, allowing only spotty unclassified appearance of X-15B-related items. (42) Reasons exist to believe interest in the X-15B shifted from WADC to the Western Development Division, home of the military space program. (43) Lacking external visibility due to classification, the X-15B might seem to have received sporadic interest.
Instead, it the X-15B as a viable proposal intended to achieve human spaceflight early while retaining some operational capability had not gone away. Instead of simply paving the technological way for the DYNA-SOAR, the serious possibility arose that the X-15B might achieve orbit earlier, as the DYNA-SOAR ran into significant technological problems. DYNA-SOAR's truly unique problems resulted in its clearly falling behind, so it was not on the path to the earliest human spaceflight.
As the Air Force cast about for a suitable operational response to SPUTNIK, the X-15B might provide not only an early capability, but one that also possessed some operational utility--not as a replacement for DYNA-SOAR, but as an interim. Thus, as DYNA-SOAR slipped to the right, the X-15B retained interest. In addition to its anticipated earlier orbital flight possibility, the X-15B objectives to demonstrate and prove technologies for the DYNA-SOAR and satellites seemed to come at a low cost per spaceflight while retaining residual operational utility.
Had the X-15B become a competitor to the DYNA-SOAR? By November 1959, the X-15B studies advanced far enough to answer the key questions about making the X-15 orbital, also answering whether the X-15B had become the DYNA-SOAR's competitor.
Harrison Storms, North American's Los Angeles Division vice president and chief engineer, conducted the work. (44) Recently declassified final reports, SATURN/X-15 Flight Research Program Report, and its companion, Technical Summary Report, SATURN/X-15, at last give insight into the fate of the X-15B. (45)
X-15B Program Overview
The detailed studies of the X-15B's design and flight operations demonstrated the move from sub-orbital to orbital flight was larger than had been anticipated.
The X-15B program comprised four initial orbital flights. A "series of tests for attaining ... national objectives" would "make substantial contributions to the development of vast numbers of concepts and components envisioned for future space systems." (46) Building on the X-15 flight research program's capabilities, the X-15B added unique tests and experiments while slightly overlapping the MERCURY and CORONA/DISCOVERER programs. Four flight profiles exemplified the possible kinds of missions and planning. At the time, actual mission plans anticipated having to await the timing and progress from other programs such as MERCURY and CORONA/DISCOVERER.
The X-15B differed sufficiently from its flight research cousin that it needed qualification flight tests using the Boeing B-52 Stratofortress. Launch alternatives were air launch from a B-52 or the North American B-70 Valkyrie, contrasted with vertical launch aboard a Convair ATLAS or Martin TITAN rocket. Clusters of rockets were also a possibility, since the ATLAS and TITAN boosters alone were insufficiently powerful. These and other launch vehicle combinations reflected the emphasis on early human orbital spaceflight in the MISS program. By 1959, the studies had narrowed down the most direct, simplest and preferred method, which was the NASA SATURN.
Unlike its flight research forebear, the X-15B would deliver up to 5,000 pounds of payload with its pilot and test director for 48-hour missions. Clearly, that was more than a simple evolution of the X-15A.
Advanced did not necessarily imply completely new, however. For instance, in the X-15's proposal phase, each bidder had to address a Navy requirement for a second crewmember. (48) Also, for the January 1958 initial source selection of the System 464L, DYNA-SOAR 1, North American proposed a 15,000 pound-class vehicle based on the X-15B operating as a satelloid. (49) This idea recurred when bioastronautics requirements firmed up in 1960. (50) The X-15B studies kept such concepts alive.
Typical of the orbital research profiles was the first test carrying 4,068 pounds of equipment to 500,000 feet. During 32-orbits, the crew were to conduct tests such as:
Optical and radio telescopy
Infrared, radar and visual terrestrial observations
Human mobility in space
Biological research
Gravitational research.
The list illustrates the range of experiments and demonstrations, from theoretical scientific data gathering to practical applications with immediate utility.
The X-15B would fire retro-rockets during the 32d orbit, maneuvering for re-entry at 350,000 feet (as they thought) at 25,500 feet per second (fps). Twenty-five minutes of high-lift gliding flight would reduce these to 8,000 fps at 150,000 feet. The remainder of its flight to touchdown would mimic the X-15A, minimizing the number of unknowns in the X-15B flight profile. Thirty-two orbits drove some of the X-15B's sizing parameters. Bottled oxygen for two days in orbit imposed considerable weight penalties, making necessary a regenerative oxygen system for which no room existed in the X-15A. (51)
After understanding the first flight and making any changes, the second flight would push the altitude envelope. This flight profile evolution was a normal flight test approach. The second orbital flight would start from the same parameters as the initial flight, but then boost to 1,584,000 feet apogee (300 statute miles), with a 500,000 foot perigee. The third flight test would begin from these same elliptical orbital parameters and demonstrate aerodynamic braking and rendezvous techniques. (52) The fourth and final test flight would push the maximum altitude to 3,168,000 feet (600 statute miles) to intensify the re-entry test. In addition to tests of magnetic and gravitational fields, meteorite and radiation measurement and mass spectrometry, the flight profile included re-entry characteristics and guidance tests.
Altitude increases came at the expense of payload weight, because total weight remained about the same. Converting all the payload weight to fuel could have resulted in a 1,900 statute mile apogee. (53)
Orbital construction might also justify the X-15B. Operational human presence required space stations. Space station size outstripped the largest launch vehicles, requiring orbital construction. Conserving robotic spacecraft weight by reducing redundancy could save money. Therefore, it was "important that the concept of manual maintenance in space be investigated early in the space research program." (54)
Design Details (55)
The final detailed design work assumed the SATURN S-1 launch vehicle. The S-1 had 1,500,000 pounds of thrust, and necessitated a modified TITAN second stage with a single XLR-87 engine. Alternative second stages were the SATURN S-II or S-IV (for additional thrust of 80,000 or 800,000 pounds, respectively). (56) The X-15B retained its XLR-99 rocket from the flight research program, but added eight Rocketdyne XLR-101 rockets in the aft fuselage for retrograde thrust at the end of the mission.
A large dorsal payload bay approximately amidships had two sets of power-driven doors, accommodating a wide range of sensors and equipment. The compartment could be segmented for additional fuel tanks. The X-15B would not deploy satellites but operate installed sensors and equipment for the mission and return these, providing a versatile and reconfigurable operational vehicle. (57)
Surprisingly little information exists on the X-15B's anticipated size. Contradictory existing data at times indicates it was the same as the X-15A, or a much larger vehicle. An oxygen regeneration system, second crewmember and the long payload bay indicate that the X-15B would have been similar in planform, but necessarily scaled up from the X-15A.
The structures of the X-15A and X-15B are the most revealing part of the studies, indicating that the X-15B had to be radically different. Reentry heat loads were a major problem with significant unknowns. The best available data on the upper atmosphere, above the highest altitudes of balloon measurements, came from EXPLORER 1, which led to conservatism in estimating the potential heat loads--meaning the requirements encompassed the worst potential case. By the end of 1959, the worst-case heat loads were the ones that drove the skin and internal structure of the X-15B.
The X-15A's 1,200[degrees]F nose temperature and the wing leading edges 1,250[degrees]F allowed its skin to be Inconel X, a high strength nickel-chromium-iron alloy. In reality, the highest heat load on the X-15A was 1,250[degrees]F (although the X-15A-2 was later thought to be capable of 2,400[degrees]F at Mach 8 ). However, the X-15B's heat loads were nearly triple that of the hypersonic research aircraft, reaching 3,400[degrees]F on the nose and 4,900[degrees]F on portions of the leading edges. The X-15B's leading edge structural materials ranged from thorium oxide near the wing roots to beryllium oxide from mid-span to wingtip. Materials for the wing leading edge protective coatings ranged from columbium (good up to 2,800[degrees]F), molybdenum (3,000[degrees]F), graphite (3,800[degrees]F) and finally, tungsten (4,750[degrees]F). The trailing edges might have been Rene' 41. (58)
The internal structure of the fuselage also had to deal with high heat loads, and the X-15A's tubular steel and titanium structures were not up to the re-entry challenge. The X-15B needed a coated molybdenum structural box. (59)
Getting the X-15B to orbit proved harder than expected. After 26 months of design, from December 1959 to February 1962, fabrication would be paced by the availability of the first flight-rated engine in October 1962 (the 34th month of the development). With first vehicle delivery in January 1963, glide tests would have followed 4 months later. The second vehicle would extend speed and altitude by adding two droppable external fuel tanks. Finally, the first launch vehicle boosted flight using a dummy second stage would have been in March 1964, with orbital flights in June 1964 and every 2 months thereafter.
This schedule killed any expectation that the X-15A was a short step away from orbital flight. Also, as for its being a potential competitor to the DYNA-SOAR, the technology problems proved nearly identical, driving the long development schedule. Importantly, in 1959, DYNA-SOAR 1's scheduled first suborbital flight in July 1962 was nearly two years ahead of the X-15B's June 1964 schedule (both of which would in reality have been after John Glenn first American orbital flight in a MERCURY capsule). Hindsight shows both schedules were unachievable, although the X-15B had a smattering of greater realism because of the X-15A's on-going and highly successful flight research program.
While the nation's civil space program, by that time, was focussing on going to the Moon, the military space program had demonstrated the extensive capabilities of robotic spacecraft. As the last glimmer of interest in the X-15B waned in late 1959, the X-15B had not justified its continued support as a way to achieve early human spaceflight, or as a technology testbed for more advanced systems, or as a competitor for the first operational human spaceflight capability.
Final Thoughts
Of course, the X-15B never went beyond design studies. At the same time, it was very much a part of the swirl of evolving spaceplane concepts in the 1950s, and very much a part of the rush to put the first human into space. It was an interesting excursion into the "what ifs" of aerospace history.
More than any other program, it demonstrated the difficulties of extrapolating a research aircraft into a spaceplane. The studies disproved that the technological maturity of the X-15 could easily bootstrap an operational orbital spaceplane program. The X-15B studies identified the same technology problems facing the much more advanced DYNA-SOAR X-20, eliminating its further consideration as a means to mature technologies for the latter program. Its demise can now be said to be understandable.
Yet, in the X-15B, we see things that were both logical and yet to come. The external fuel tanks eventually flew aboard an X-15A for the same purpose as proposed in the X-15B. The dorsal payload bay flexibly containing sensors, experiments or additional fuel later made eminent sense as part of the Space Shuttle.
The studies straddled the transition of robotic spacecraft from crude demonstrations to the first operational capabilities without human presence. Robotic capabilities advanced faster than expected by those whose experience consisted of robotic aircraft programs. The rush to put humans in space for national defense or security reasons died a slow and lingering death, as enthusiasm largely dampened out based on robotic spacecraft success, combined with the high cost technically challenging aspects of human spaceflight.
As an epilogue, a little over two years after the X-15B studies, having pushed DYNA-SOAR beyond achievability, Defense Secretary Robert S. McNamara said, given "the absence of a clearly defined military manned space mission, present military efforts should be directed to the establishment of the necessary technology base and experience upon which to expand, with the shortest possible time lag, in the event firm military manned space missions and requirements are established in the future." (60) Against the earlier perception of the need for human presence to achieve true operational capabilities, robotic spacecraft progressed so rapidly that, by June 1, 1962, Director of Defense Research and Engineering Dr. Harold Brown told Congress he could not define a requirement for military manned space systems. "I think there may, in the end, turn out not to be any." (61)
The military human spaceflight tide had changed. No shortcuts to operational human spaceflight existed, then or now. But, instead of the path not taken, what might the U.S. space programs have been like, had the X-15B and space-planes been pursued?
NOTES
(1.) The most authoritative source on the X-15 program devotes parts of two pages and occasional snippets to the project, by far the most extensive discussion before this paper (Jenkins, Dennis R., Tony R. Landis, Hypersonic--The Story of the North American X-15 (North Branch, Minn: Specialty Press, 2003) pp. 209-210). The other authoritative source on hypersonic research programs was Richard P. Hallion's comprehensive two-volume work (Hallion, Richard P., The Hypersonic Revolution (Wright-Patterson Air Force Base, Ohio: Special Staff Office, 1987) Vol. I, p. I-x), whose scant references to the X-15B suggested that concept was successively shelved and revived for years, finally yielding to the MERCURY capsule. None of the sources, however, adequately explains the designation change of the X-15 to the X-15A. This is usually not mentioned, or discussed only as it applies to the heavily redesigned X-15A-2 (with external fuel tanks). It would appear that the redesignation may actually have been tied to the serious pursuit of the orbital X-15, necessitating a "B" to differentiate its significant differences from the X-15 research aircraft, subsequently designated "A." This supposition, however, seems equally unprovable. Readers interested in the X-15 program itself should also refer to sources such as Jay Miller, X-Planes: X-1 to X-45; Milton Thompson, At the Edge of Space; and Robert Godwin, X-15: The NASA Mission Reports.
(2.) Johnson, Clarence L., M. Smith, Kelly: More Than My Share Of It All (Washington, D.C: Smithsonian Institution Press, 1985); Rich, Ben R. and Leo Janos, Skunk Works -A Personal Memoir of My Years at Lockheed (New York: Little, Brown and Company, 1994), pp. 169-174. Johnson was seemingly aware of and more concerned with how to meet the Air Force's General Operating Requirement 12, the Special Reconnaissance System, discussed below, released within a few months of this meeting.
(3.) Jenkins and Landis 2003, p. 19.
(4.) Ibid; Crowley, Gus. "Minutes of the Meeting, NACA Committee on Aerodynamics," October 4-5, 1954 (Washington, D.C: Files of the NASA History Office).
(5.) Murray, Arthur, Man's Role in Dyna-Soar Flight (Seattle, Wash: The Boeing Company, August 1962, declassified 1965), D2-80726; Temple, L. Parker III, Shades of Gray, National Security and the Evolution of the National Reconnaissance Office (Reston, Va: American Institute of Aeronautics and Astronautics, 2005), pp. 135-137. The latter contains a more complete list, explanation and critique of the list.
(6.) Aviation Week, Mar 10, 1958, p. 39.
(7.) Hansen, James R., Engineer in Charge (Washington, DC: National Aeronautics and Space Administration, 1986), NASA SP-4305, p. 356; Becker, John V., "The Development of Winged Re-entry Vehicles, 1952-1963," unpublished, May 23, 1983, copy in NASA Langley Research Center Historical Archive. Dornberger even pushed to have Bell Aircraft hire Sanger, but this never worked out.
(8.) York, Herbert F., Arms and the Physicist: An Eyewitness Report on a Half Century of Nuclear-Age Drama (New York: Springer-Verlag, 1994), Vol. 12, p. 129-130. Former Director, Defense Research and Engineering, Dr. Herbert York says Dornberger proudly recalled the number to show how indecisive the US government was. To York, however, it only proved how persistent Dornberger was.
(9.) Hall, R. Cargill, C.D. Laurie, eds. Early Cold War Overflights--1950-1956, Symposium Proceedings (Washington, D.C: National Reconnaissance Office, 2003), passim.
(10.) U.S. Congress, House, Committee on Government Operations, Organization and Management of Missile Programs, 86th Congress, 1st Session, Sep 2, 1959, House Report 1121, p. 127.
(11.) Becker 1983, 20; Hansen 1986, pp. 367-368.
(12.) Aviation Week Feb 3, 1958, p. 26.
(13.) Becker 1983, p. 15.
(14.) Temple 2005, p. 134.
(15.) Bowen, Lee, The Threshold of Space: The Air Force in the National Space Program, 1949-1959 (Washington, D.C: USAF Historical Division Liaison Office, 1960), p. 23; Hallion 1987, Vol. 2, pp. 1989. This idea that technology needs could be met in another program not directly related would come back in the more advanced DYNA-SOAR. The designation X-15A is used in this paper to consistently refer to the hypersonic research aircraft, despite the fact that the designation was not used in the early part of the program.
(16.) Becker 1983, pp. 18-19.
(17.) Hallion 1987, Vol. 2, p. 209; Temple 2005, p. 134.
(18.) Hallion 1987, Ibid. Note the advancement in the schedule from the early three-phased program. After combining the projects, first phase development time reduced by three years.
(19.) Headquarters, Air Research and Development Command, "System Development Directive 464L," December 21, 1957, pp. 2, 8, 11, 32; Headquarters, Air Research and Development Command, Detachment 1, "Preliminary Development Plan, System 464L," November 1958; Butz, J.S. Jr., "Orbital Re-Entry Will Intensify Demands On Structures," Aviation Week & Space Technology, April 21, 1958, pp. 50-51. I chose the December 21 date because it records the formalization of a decision reached in the Air Force on October 10 collapsing the efforts into one program. When General White spoke in mid-December, the decision to create DYNA-SOAR out of the other programs was already publicly released.
(20.) Bowen, Ibid.
(21.) White, General Thomas D., "Leadership--in the Conquest of Space," address to the Air Force Academy, December 14, 1957.
(22.) Gantz, Lt.Col. Kenneth F., ed., The United States Air Force Report on the Ballistic Missile--Its Technology, Logistics and Strategy (New York: Doubleday and Company, Inc., 1958), p. 277.
(23.) Jenkins and Landis 2003, p. 209.
(24.) NAVAHO was a supersonic, rocket boosted, ramjet powered cruise missile under development for the Air Force. Subscale models, designated X-10, flew in the mid-1950s, but the project was cancelled in favor of the ATLAS missile. At the time of the X-15B studies, the NAVAHO was in serious technical trouble, but represented an approach well understood by North American engineers.
(25.) Jenkins and Landis, Ibid.
(26.) Syvertson, Clarence A., "Visit to WADC, Wright-Patterson Air Force Base, Ohio, to attend conference on January 29-31, 1958, concerning research problems associated with a man in a satellite vehicle," Memorandum for Director, February 13, 1958, pp. 8-9, in the Headquarters NASA History Office X-15 files.
(27.) Hallion 1987, Vol. 1, p. 8.
(28.) Hallion 1987, Vol. 2, pp. 204-207.
(29.) Syvertson 1958, p. 1.
(30.) Syvertson 1958, p. 9. Becker's responsibilities had included getting the X-15 program going and later serving as NASA's project manager on DYNA-SOAR. His "lessons learned" version of the WADC meeting is in Hallion 1987, Vol. 1, p. 411. The eleven MISS alternatives to early human spaceflight covered the gamut from spheres to missile re-entry nose cone adaptations, to the "stripped" X-15B and winged re-entry vehicles like DYNA-SOAR. Of note in his summary of the 11 alternatives was the absence of Boeing's DYNA-SOAR boost-glide vehicle, which was already well underway, but whose schedule did not fall within the bounds of attaining early human spaceflight. In its place, the only boost-glide vehicles presented were the Northrop and Bell proposals for DYNA-SOAR.
(31.) I owe the satelloid-boost-glide distinction to Hallion (Hallion 1987, Vol. 1, p. 210), which I expanded to differentiate the ballistic vehicles such as the blunt MERCURY capsule, spheres, and missile re-entry shapes. This distinction of Hallion's is especially important to understand the difference between the final version and expectations of the X-20 and the original DYNA-SOAR 1. Originally designed for one purpose as a boost-glide vehicle, circumstances forced it into regimes it was not well suited to operate as a satelloid, which was a major part of the projects undoing.
(32.) Temple 2005, p. 325; Perry, Robert L., A History of Satellite Reconnaissance, Volume IIB--SAMOS E-5 and E-6 (Washington, D.C: The National Reconnaissance Office, October 1973, declassified September 2002), pp. 424-427; Day, Dwayne A., "A Sheep in Wolf's Clothing," Spaceflight, 44, October 2002, p. 10. SENTRY, the original designation of the Air Force photoreconnaissance program under WS-117L, changed to SAMOS in Aug 1959. For narrative simplicity, SAMOS is used consistently here. Several versions of the SENTRY capsules had removed much of the photoreconnaissance equipment replaced by human spaceflight equipment (and crew). These latter concepts were essentially packaging studies, to see whether a human and associated support could be fit into the space left by removing the camera. In some cases, the capsule itself was extended to include both camera and human, but that defeated the cover story by having an outwardly distinguishable capsule for reconnaissance and one for human spaceflight. The packaging was related to the launch vehicle-driven maximum capsule diameter. The SAMOS E-6 was to use a scaled-up TITAN II re-entry vehicle. To accommodate the large format camera, the E-6 was approximately 12 feet long and 8 foot across at the base, easily large enough for a seated astronaut. The CORONA program expended the camera, returning only the film, allowing (in early models) a much smaller size. Day's article covers the rest of the attempts to mix human spaceflight with various SENTRY/SAMOS capsules, such as in the E-3 and E-5.
(33.) Hallion 1987, Vol. 1, p. lxxwiii.
(34.) As explained in this article, the most common assertion about the X-15B is that it kept getting shelved and revived. This paper shows greater continuity behind the X-15B investigations, though some may find it interesting to note that the up-scaled human spaceflight version of the RVX-2 enjoyed its own shelving and reintroduction in the early 1980s. The concept was briefly alive again in the very early days after the establishment of Air Force Space Command. The author of this article was called upon to review this proposal while assigned to Air Force Systems Command at the time.
(35.) Temple 2005, p. 325; Day, Dwayne A., John M. Logsdon and Brian Latell, eds., Eye in the Sky--The Story of the CORONA Spy Satellites (Washington, D.C: Smithsonian Institution Press, 1998), p. 74.
(36.) Hallion 1987, Vol. 1, p. 411. Heroic human presence as fundamental to real capabilities was popularized in Tom Wolfe's best-selling book, The Right Stuff, minimizing the role of humans in the orbital MERCURY capsules.
(37.) Temple 2005, p. 144; Hallion 1987, Vol. 1, p. 411.
(38.) Swenson, Lloyd S., Jr., James M. Greenwood, and Charles C. Alexander, This New Ocean: A History of Project Mercury, (Washington, D.C: National Aeronautics and Space Administration, 1966), pp. 78-80.
(39.) Temple 2005, p. 144.
(40.) Syvertson 1958, p. 11. Syverston sketched each of the basic shapes and then detailed important aspects of each of the 11 concepts, one being the estimated development time to manned spaceflight.
(41.) Jenkins and Landis 2003, Ibid.
(42.) Gantz 1958, pp. 296-297. In testimony before the Senate Committee on Armed Services' Preparedness Investigating Subcommittee, referring to the "manned satellite," General Schriever said he preferred "not to say anything more about the program that has been under discussion ... because of its classification." When Congressman Weisl clarified the question referred to the X-15, Schriever explained that the X-15 was not a satellite, but a rocket-powered airplane. Senator Barrett responded, "Yes, I understand that, General, but I was thinking about an extension of the X-15, and it would be perfectly agreeable to wait for executive session." Schriever explained its relationship to the hardware then in existence supporting the ballistic missile program. Experimental recovery flights were possible with existing hardware, he claimed. The testimony was on December 17, 1957 and January 8-9, 1958.
(43.) This effort comprising only studies is very difficult to reconstruct. Western Development Division was indeed involved in the evaluation and possibly sponsorship of the X-15/SATURN in 1959, when Jenkins and Hallion indicate it had been shelved. The two Air Force development centers responsible for aircraft and satellites had a lengthy rivalry on the topic of spaceplanes. Each center had its own ways to extend aircraft technology higher and faster to become satellites or to make satellite technology capable of aerodynamic flight. I suspect that, as interest in the X-15B waned at Wright Air Development Center, it was either picked up briefly or worked collaterally at Western Development Division. This is not yet provable. I documented some of this rivalry relating to spaceplanes in Shades of Gray.
(44.) Jenkins and Landis 2003, Ibid.
(45.) North American Aviation Report, SATURN/X-15 Flight Research Program Report, November 19, 1959, NA 59-1586, SECRET original declassified by NASA Headquarters, 9 and passim; North American Aviation Report, Technical Summary Report, SATURN/X-15, November 19, 1959, NA 59-1247, SECRET original declassified by NASA Headquarters, passim. These newly declassified reports were obtained through FOIA from NASA Headquarters.
(46.) North American Aviation Report, NA 59-1586, p. 5.
(47.) North American Aviation Report, NA 59-1586, restored from the original by Ms. Betty Temple, as with all drawings in this article.
(48.) Jenkins and Landis 2003, p. 28.
(49.) Hallion 1986, Vol., 1, pp. 209-210.
(50.) Jenkins and Landis 2003, p. 163.
(51.) The X-15 life support system used oxygen stored in canisters, sufficient for short duration atmospheric missions, but not for long duration orbital missions. Adding more oxygen bottles would be costly in terms of weight and performance, as well as operationally limiting. Orbital flight would have required some form of regenerative breathing system. At the time, the rule of thumb that one pound into 100 nautical mile orbit required 100 pounds of fuel and launch vehicle was unknown, but the expense of extra weight was appreciated. The X-15B studies showed a good anticipatory understanding of the kinds of tradeoffs between fuel and payload each profile represented.
(52.) North American Aviation Report, NA 59-1586, p. 6.
(53.) North American Aviation Report, NA 59-1586, p. 29.
(54.) North American Aviation Report, NA 59-1586, p. 12.
(55.) For a more detailed description of the technical details of the X-15B, see Temple, L. Parker III, "X-15B: The Spaceplane That Almost Was," Paper presented at the 57th International Astronautical Congress, Valencia, Spain, October 2006, IAC-06-E4.3.01.
(56.) North American Aviation Report, NA 59-1247, 8.
(57.) The payload bay was narrow and long, apparently displacing one fuel tank from the original X-15 design. Interestingly, surviving cutaway drawings in the technical reports show a dorsal payload bay, but do not remove the internal fuel tank, which is contradictory.
(58.) North American Aviation Report, NA 59-1247, pp. 95, 102; North American Aviation Report, NA 59-1586, p. 96. Interestingly, at the same time columbium was considered the material for the X-20 DYNA-SOAR, but the amount required exceeded the world's annual production of the element. Had both continued, there would have been competition for resources to complicate their acquisition.
(59.) Jenkins and Landis 2003, pp. 179, 181; Hallion 1986, Vol. 1, pp. 35-37; North American Aviation Report, NA 59-1247, pp. 95, 102.
(60.) Carter, Launor F., Interpretive Study of the Formulation of the Air Force Space Program (Washington, D.C: US Air Force History Office, February 4, 1963), pp. 3, 16.
(61.) U.S. Congress, House, Committee on Government Operations, 85th Congress, 2nd Session, June 4, 1965, House Report 445, p. 82; U.S. Congress, Senate, Committee on Aeronautical and Space Sciences, NASA Authorization for fiscal year 1963, 87th Congress, 2nd Session, June 1962, p. 348. This was hardly the end of the push for military human spaceflight, but the subsequent absence of such programs speaks volumes about the realities. Conceptual studies replaced the efforts aimed at actually developing flying systems, as both Air Force Systems Command's Aeronautical Systems Division and its Space and Missile Systems organization/Space Systems Division pursued concepts variously named Aerospaceplane, Trans-Atmospheric Vehicles, Reusable Aerodynamic Space Vehicles, and other names. These are covered in more detail in Temple, 2005, passim Improved rocket technology and other advances brought space-planes back into vogue in the late 1980s with the National Aerospace Plane (NASP). However, neither the NASP nor any of its predecessors were ever considered to be the key to operational uses of space--robotic spacecraft remain unchallenged for their operational utility to this day.
Dr. L. Parker Temple works on space programs as a systems engineer, but also has a second career as an historian. He was a career Air Force officer, combining a career of flying, promulgating space policy and space systems acquisition. Recently, he was honored by his election as a Fellow of the American Institute of Aeronautics and Astronautics, and was the author of AIAA's best selling book, Shades of Gray, National Security and the Evolution of the National Reconnaissance Office.
He currently lives in Virginia.
COPYRIGHT 2008 Air Force Historical Foundation
COPYRIGHT 2008 Gale, Cengage Learning
North American X-15
From Wikipedia, the free encyclopedia
X-15
Role
Experimental high-speed rocket-powered research aircraft
Manufacturer: North American Aviation
First flight: 8 June 1959
Introduced: 17 September 1959
Retired: December 1970
Primary users: United States Air Force and NASA
Number built: 3
The North American X-15 rocket-powered aircraft/spaceplane was part of the X-series of experimental aircraft, initiated with the Bell X-1, that were made for the USAAF/ USAF, NACA/NASA, and the USN. The X-15 set speed and altitude records in the early 1960s, reaching the edge of outer space and returning with valuable data used in aircraft and spacecraft design. As of 2011, it holds the official world record for the fastest speed ever reached by a manned rocket-powered aircraft.[1]
During the X-15 program, 13 of the flights (by eight pilots) met the USAF spaceflight criteria by exceeding the altitude of 50 miles (80.5 km, 264,000 ft), thus qualifying the pilots for astronaut status. The USAF pilots qualified for USAF astronaut wings, while the civilian pilots were later awarded NASA astronaut wings.[2][3]
Of all the X-15 missions, two flights (by the same pilot) qualified as space flights per the international (Fédération Aéronautique Internationale) definition of a spaceflight by exceeding 100 kilometres (62.1 mi, 328,084 ft) in altitude.
Contents
Design and development
X-15 just after release.
X-15 touching down on its skids. Compare jettisoned lower ventral fin with color picture, top.
The X-15 was based on a concept study from Walter Dornberger for the NACA for a hypersonic research aircraft.[4] The requests for proposal were published on 30 December 1954 for the airframe and on 4 February 1955 for the rocket engine. The X-15 was built by two manufacturers: North American Aviation was contracted for the airframe in November 1955, and Reaction Motors was contracted for building the engines in 1956.
Like most X-series aircraft, the X-15 was designed to be carried aloft, under the wing of a NASA B-52, the Balls 8. Release took place at an altitude of about 8.5 miles (13.7 km, 45,000 ft), and a speed of about 805 km/h (500 mph, 223.5 m/s).[5] The X-15 fuselage was long and cylindrical, with rear fairings that flattened its appearance, and thick, dorsal and ventral wedge-fin stabilizers. Parts of the fuselage were heat-resistant nickel alloy (Inconel-X 750).[4] The retractable landing gear comprised a nose-wheel carriage and two rear skis. The skis did not extend beyond the ventral fin, which required the pilot to jettison the lower fin (fitted with a parachute) just before landing. The two XLR-11 rocket engines for the initial X-15A model delivered 16,000 lbf (71 kN) maximum thrust each, for a total of 32,000 pounds-force. The main engine (installed later) was a single XLR-99 rocket engine delivering 57,000 lbf (250 kN) at sea level, and 70,000 lbf (310 kN) at peak altitude. The idle thrust of the XLR-99 was 15,000 lbf (67 kN).
Engines and fuel
Early flights used two Reaction Motors XLR11 engines. Later flights were undertaken with a single Reaction Motors Inc XLR99 rocket engine generating 57,000 pounds-force (250 kN) of thrust powered the aircraft. This engine used ammonia and liquid oxygen for propellant and hydrogen peroxide to drive the high-speed turbopump that delivered fuel to the engine. The XLR99 could be throttled, and were the first such controllable engines that were "man-rated",[disputed – discuss] that is, declared safe to operate with a human aboard.[citation needed]
Operational history
Three X-15s were built, flying 199 test flights, the last on 24 October 1968. The first X-15 flight was an unpowered test flight by Scott Crossfield, on 8 June 1959; he also piloted the first powered flight, on 17 September 1959, with his first XLR-99 flight on 15 November 1960. Twelve test pilots flew the X-15; among them were Neil Armstrong (first man to walk on the moon) and Joe Engle (later a space shuttle commander). In July and August 1963, pilot Joe Walker crossed the 100 km altitude mark, joining the NASA astronauts and Soviet Cosmonauts as the first humans to have crossed the barrier into outer space (Soviet Yuri Gagarin was the first person in space, reaching 327 km in apogee of his orbital flight, while Alan Shepard was the first American in space, reaching 187 km during suborbital flight) and becoming the first to exceed this threshold twice.
U.S. Air Force test pilot Major Michael J. Adams was killed on 15 November 1967 in X-15 Flight 191 when his craft (X-15-3) entered a hypersonic spin while descending, then oscillated violently as aerodynamic forces increased after re-entry. As his craft's flight control system operated the control surfaces to their limits, the craft's acceleration built to 15 g vertical and 8 g lateral. The airframe broke apart at 60,000 ft (18,000 m) altitude, scattering the craft's wreckage for 50 square miles (130 km2). On 8 June 2004, a monument was erected at the cockpit's locale, near Randsburg, California.[6] Major Adams was posthumously awarded Air Force astronaut wings for his final flight in craft X-15-3, which had reached 81.1 km (50.4 mi, 266,000 ft) of altitude. In 1991, his name was added to the Astronaut Memorial.
Bomber NB-52A (s/n 52-003), permanent test variant, carrying an X-15, with mission markings; horizontal X-15 craft silhouettes denote glide flights, diagonal silhouettes denote powered flights.
The second X-15A was rebuilt after a landing accident. It was lengthened 2.4 feet (0.73 m), a pair of auxiliary fuel tanks attached under the fuselage, and a heat-resistant surface treatment applied. Re-named the X-15A-2, it first flew on 28 June 1964, reaching 7,274 km/h (4,520 mph, 2,021 m/s).
The altitudes attained by the X-15 aircraft do not match that of Alan Shepard's 1961 NASA space capsule flight nor subsequent NASA space capsules and space shuttle flights. However, the X-15 flights did reign supreme among rocket-powered aircraft until the second spaceflight of Space Ship One in 2004.
Five aircraft were used for the X-15 program: three X-15s, two B-52 bombers:
X-15A-1 – 56-6670, 82 powered flights
X-15A-2 – 56-6671, 53 powered flights
X-15A-3 – 56-6672, 64 powered flights
NB-52A – 52-003 (retired in October 1969)
NB-52B – 52-008 (retired in November 2004)
A 200th flight over Nevada was slated for 21 November 1968, piloted by William J. Knight. Technical problems and bad weather delayed the flight six times, and on 20 December 1968, the 200th flight was finally cancelled. The X-15 was detached from the NB-52A wing and prepared for indefinite storage.
Gallery
X-15 gallery
X-15A-2 on the flight line
X-15 on Boeing B-52 Mothership wing pylon
X-15 in full scale ablative coating
X-15 on display at the National Air and Space Museum
X-15 nose
Current static displays
X-15 at the National Air and Space Museum X-15-1 (s/n 56-6670) is on display in the National Air and Space Museum "Milestones of Flight" gallery, Washington, D.C.
X-15-2A (s/n 56-6671) is at the National Museum of the United States Air Force, at Wright-Patterson Air Force Base, near Dayton, Ohio. It was retired to the Museum in October 1969.[7] The aircraft is displayed in the Museum's Research & Development Hangar alongside other "X-planes", including the Bell X-1 and X-3 Stiletto.
X-15-3 (s/n 56-6672) was destroyed. Parts have been recovered at the crash site as late as the 1990s.
X-15A2 with external fuel tanks, white ablative paint, and mock-up of "Scram-Jet" engine.
The Scram-Jet engine project was never completed, and only the non-functional mock-up was flight
tested. The Scram-Jet mockup is on display at the US Air Force Museum in Dayton Ohio.
Mock-ups
Dryden Flight Research Center, Edwards AFB, California, USA (painted with s/n 56-6672)
Pima Air Museum, Tucson, Arizona (painted with s/n 56-6671)
Evergreen Aviation Museum, McMinnville, Oregon (painted with s/n 56-6672). A full-scale wooden mock-up of the X-15, displayed along with one of the rocket motors.
Stratofortress motherships
NB-52A (s/n 52-003) is at the Pima Air and Space Museum, Tucson, Arizona. It launched the X-15 #1 30 times, the X-15 #2, 11 times, and the X-15 #3 31 times (as well as the M2-F2 four times, the HL-10 11 times and the X-24A twice).
NB-52B (s/n 52-008) is at the Dryden Flight Research Center, Edwards AFB, California, USA. It launched the majority of X-15 flights.
Aftermath
Before 1958, USAF and NACA, (later NASA), officials discussed an orbital X-15 spacecraft—the X-15B—for launching to outer space atop an SM-64 Navajo missile. This was canceled when NACA became NASA, and Project Mercury was approved instead. By 1959, the X-20 Dyna-Soar space-glider program became the USAF's preferred means for launching military manned spacecraft into orbit; however, this program was canceled in the early 1960s before an operational vehicle could be built.[2]
Record flights
Highest flights
There are two definitions of how high a person must go to be referred to as an astronaut. The USAF decided to award astronaut wings to anyone who achieved an altitude of 50 miles (80.5 km) or more. However, the FAI set the limit of space at 100 kilometres (62.1 mi). Thirteen X-15 flights went higher than 50 miles and two of these reached over 100 kilometres.
X-15 flights higher than 50 mi (80 km)
Flight Flight 62 Flight 77 Flight 87
Date 17 July 1962 17 January 1963 27 June 1963
Top speed 3,831 mph (6,165 km/h) 3,677 mph (5,918 km/h) 3,425 mph (5,512 km/h)
Altitude 59.6 miles (95.9 km) 51.4 miles (82.7 km) 53.9 miles (86.7 km)
Pilot Robert M. White Joe Walker Robert Rushworth
Flight Flight 90 Flight 91 Flight 138
Date 19 July 1963 22 August 1963 29 June 1965
Top Speed 3,710 mph (5,970 km/h) 3,794 mph (6,106 km/h) 3,431 mph (5,522 km/h)
Altitude 65.8 miles (105.9 km) 67.0 miles (107.8 km) 53.1 miles (85.5 km)
Pilot Joe Walker Joe Walker Joseph H. Engle
Flight Flight 143 Flight 150 Flight 153
Date 10 August 1965 28 September 1965 14 October 1965
Top Speed 3,549 mph (5,712 km/h) 3,731 mph (6,004 km/h) 3,554 mph (5,720 km/h)
Altitude 51.3 miles (82.6 km) 55.9 miles (90.0 km) 50.4 miles (81.1 km)
Pilot Joseph H. Engle John B. McKay Joseph H. Engle
Flight Flight 174 Flight 190 Flight 191
Date 1 November 1966 17 October 1967 15 November 1967
Top Speed 3,750 mph (6,040 km/h) 3,856 mph (6,206 km/h) 3,569 mph (5,744 km/h)
Altitude 58.1 miles (93.5 km) 53.1 miles (85.5 km) 50.3 miles (81.0 km)
Pilot Bill Dana Pete Knight Michael J. Adams†
Flight Flight 197
Date 21 August 1968
Top Speed 3,443 mph (5,541 km/h)
Altitude 50.6 miles (81.4 km)
Pilot Bill Dana
† fatal
Fastest flights
X-15 10 fastest flights
Flight Flight 45 Flight 59 Flight 64
Date 9 November 1961 27 June 1962 26 July 1962
Top Speed 4,092 mph (6,585 km/h) 4,104 mph (6,605 km/h) 3,989 mph (6,420 km/h)
Altitude 19.2 miles (30.9 km) 23.4 miles (37.7 km) 18.7 miles (30.1 km)
Pilot Robert M. White Joe Walker Neil Armstrong
Flight Flight 86 Flight 89 Flight 97
Date 25 June 1963 18 July 1963 5 December 1963
Top Speed 3,910 mph (6,290 km/h) 3,925 mph (6,317 km/h) 4,017 mph (6,465 km/h)
Altitude 21.7 miles (34.9 km) 19.8 miles (31.9 km) 19.1 miles (30.7 km)
Pilot Joe Walker Robert Rushworth Robert Rushworth
Flight Flight 105 Flight 137 Flight 175
Date 29 April 1964 22 June 1965 18 November 1966
Top Speed 3,905 mph (6,284 km/h) 3,938 mph (6,338 km/h) 4,250 mph (6,840 km/h)
Altitude 19.2 miles (30.9 km) 29.5 miles (47.5 km) 18.7 miles (30.1 km)
Pilot Robert Rushworth John B. McKay Pete Knight
Flight Flight 188
Date 3 October 1967
Top Speed 4,519 mph (7,273 km/h)
Altitude 19.3 miles (31.1 km)
Pilot Pete Knight
X-15 pilots
X-15 pilots and their achievements during the program
Pilot Michael J. Adams† Neil Armstrong Scott Crossfield Bill Dana Joseph H. Engle
Organization USAF NASA North American NASA USAF
Aviation
Total 7 7 14 16 16
Flights
USAF 1 0 0 2 3
space
flights
FAI 0 0 0 0 0
space
flights
Max 5.59 5.74 2.97 5.53 5.71
Mach
Max 3,822 3,989 1,959 3,897 3,887
speed
(mph)
Max 50.3 39.2 15.3 58.1 53.1
altitude
(miles)
Pilot Pete Knight John B. McKay Forrest S. Petersen Robert A. Rushworth
Organization USAF NASA USN USAF
Total 16 29 5 34
Flights
USAF 1 1 0 1
Space
Flights
FAI 0 0 0 0
Space
Flights
Max. 6.70 5.65 5.3 6.6
Mach
Max. 4,519 3,863 3,600 4,017
Speed
(MPH)
Max. 53.1 55.9 19.2 53.9
Altitude
(Miles)
Pilot Milt Thompson Joe Walker Robert M. White*
Organization NASA USAF USAF
Total
Flights 14 25 16
USAF
Space
Flights 0 3 1
FAI
Space
Flights 0 2 0
Max.
Mach 5.48 5.92 6.04
Max.
Speed
(MPH) 3,723 4,104 4,092
Max.
Altitude
(Miles) 40.5 67.0 59.6
† Killed • * White was backup for Captain Iven Kincheloe
Specifications (X-15)
General characteristics
Crew: one
Length: 50 ft 9 in (15.45 m)
Wingspan: 22 ft 4 in (6.8 m)
Height: 13 ft 6 in (4.12 m)
Wing area: 200 ft2 (18.6 m2)
Empty weight: 14,600 lb (6,620 kg)
Loaded weight: 34,000 lb (15,420 kg)
Max takeoff weight: 34,000 lb (15,420 kg)
Powerplant: 1 × Thiokol XLR99-RM-2 liquid-fuel rocket engine, 70,400 lbf at 30 km (313 kN)
Performance
Maximum speed: Mach 6.72 (4,520 mph, 7,274 km/h)
Range: 280 mi (450 km)
Service ceiling: 67 mi (108 km, 354,330 ft)
Rate of climb: 60,000 ft/min (18,288 m/min)
Wing loading: 170 lb/ft2 (829 kg/m2)
Thrust/weight: 2.07
References
Notes
1.^ Aircraft Museum X-15." Aerospaceweb.org, 24 November 2008.
2.^ a b Jenkins, Dennis R. Space Shuttle: The History of the National Space Transportation System: The First 100 Missions, 3rd edition. Stillwater, Minnesota: Voyageur Press, 2001. ISBN 0-9633974-5-1.
3.^ "NASA astronaut wings award ceremony". NASA Press Release, 23 August 2005.
4.^ a b Käsmann 1999, p. 105.
5.^ "X-15 launch from B-52 mothership." Dryden Flight Research Center Photo Collection. Retrieved: 8 February 2011.
6.^ X-15A Crash site
7.^ United States Air Force Museum 1975, p. 73.
Bibliography
"SP-2000-4531: American X-Vehicles: An Inventory X-1 to X-50." NASA, June 2003.
"Flight experience with shock impingement and interference heating on the X-15-2 research airplane 1968." NASA.
Godwin, Robert, ed. X-15: The NASA Mission Reports. Burlington, Ontario: Apogee Books, 2001. ISBN 1-896522-65-3.
Hallion, Dr. Richard P. "Saga of the Rocket Ships." AirEnthusiast Six, March–June 1978. Bromley, Kent, UK: Pilot Press Ltd.
Käsmann, Ferdinand C.W. "Die schnellsten Jets der Welt". Weltrekord-Flugzeuge [World Speed Record Aircraft] (in German). Kolpingring, Germany: Aviatic Verlag, 1999. ISBN 3-925505-26-1.
"Thermal protection system X-15A-2 Design report." NASA report 1968 (PDF format).
Thompson, Milton O. and Neil Armstrong. At the Edge of Space: The X-15 Flight Program. Washington, DC: Smithsonian Institution Press, 1992. ISBN 1-56098-107-5.
Tregaskis, Richard. X-15 Diary: The Story of America's First Space Ship. Lincoln, Nebraska: iUniverse.com, 2000. ISBN 0-595-00250-1.
United States Air Force Museum Guidebook. Wright-Patterson AFB, Ohio: Air Force Museum Foundation, 1975.
"X-15 research results with a selected bibliography." NASA report (PDF format).
"X-15: Extending the Frontiers of Flight." NASA (PDF format).
Additional, from fighter-planes.com:
On the limit of aircraft and spacecraft, the X-15 reached Mach 6.72 and an height of 107960 m. The X-15 was designed to resist the heat and friction of atmospheric reentry. It was powered by rocket engines. The X-15A-2 version could carry two large external fuel tanks. Three X-15s were built, one was lost in a fatal accident.
Type: X-15A
Country: USA
Function: experimental
Year: 1959
Crew: 1
Engines: 1 * 31750 kg Reaction Motors XLR-99 (liquid-fuel rocket engine)
Wing Span: 6.71 m
Length: 15.24 m
Height: 4.12 m
Wing Area: 18.58 m2
Empty Weight: 6623 kg
Max.Weight: 15422 kg
Speed: 6600 km/h
Ceiling: 95900 m
Rate of climb: 18000 m/min
Range: 450 km
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The North American X-15 rocket plane was perhaps the most important of the USAF/USN X-series of experimental aircraft. Although not as famous as the Bell X-1, the X-15 set numerous speed and altitude records in the early 1960s, reaching the edge of space and bringing back valuable data that was used in the design of later aircraft and spacecraft.
During the X-15 program, 13 flights met the US criterion for a spaceflight by passing an altitude of 50 miles (80 km) and the pilots were accordingly awarded astronaut status by the USAF. Out of these, 2 also qualified for the international FAI definition of a spaceflight by passing the 62.1 miles (100 km) mark.
History
The original Request for Proposals was issued for the airframe December 30, 1954, and for the rocket engine on February 4, 1955. North American received the airframe contract in November 1955, and Reaction Motors contracted in 1956 to build the engines.
As with many of the X-aircraft, the X-15 was designed to be carried aloft under the wing of a B-52. The fuselage was long and cylindrical, with fairings towards the rear giving it a flattened look, and it had thick wedge-shaped dorsal and ventral fins. The retractable landing gear consisted of a nose wheel and two skids to provide sufficient clearance part of the ventral fin had to be jettisoned before landing. The two XLR-11 rocket engines of the initial model X-15A delivered 36 kN (8,000 lbf) of thrust; the "real" engine that came later was a single XLR-99 that delivered 254 kN (57,000 lbf) at sea level, and 311 kN (70,000 lbf) at peak altitude.
The first flight was an unpowered test made by Scott Crossfield on June 8, 1959, who followed up with the first powered flight on September 17. The first flight with the XLR-99 was on 15 November 1960.
Three X-15s were built in all, and they made a total of 199 test flights, the last one on October 24, 1968. Plans were made for a 200th X-15 flight to be launched over Smith Ranch, Nevada. It was scheduled for November 21, 1968 with William J. Knight as the pilot. Various technical and weather delays caused the planned launch to slip at least six times until late December, 1968. Finally after a cancellation on December 20, 1968 due to weather, it was decided there would not be a 200th flight. The X-15 ground crew de-mated the aircraft from the NB-52A, and prepared it for indefinite storage. X-15 #1 was sent to the National Air and Space Museum in Washington, DC. X-15 #2 is on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio. X-15 #3, 56-6672, was destroyed in a crash on November 15, 1967.
Twelve test pilots flew the plane, including Neil Armstrong, later the first man on the Moon and Joe Engle who went on to command Space Shuttle missions. In July and August, 1963, pilot Joe Walker crossed the 100 km altitude mark twice, becoming the first person to enter space twice.
Test pilot Michael J. Adams was killed on November 15, 1967 when his X-15-3 began to spin on descent and then disintegrated when the acceleration reached 15 g (147 m/s²), scattering wreckage over 50 square miles. On June 8, 2004 a memorial monument was erected at the location of cockpit crash site near Randsburg, California. Michael Adams was posthumously awarded astronaut wings for his last flight in the X-15-3, which had attained an altitude of 266,000 feet (81.1 Km). In 1991 Adams' name was added to the Astronaut Memorial at the Kennedy Space Center in Florida.
The second X-15A was rebuilt after a landing accident. It was lengthened by about 0.74 m (2.4 ft), received a pair of auxiliary fuel tanks slung under the fuselage, and was given a heat-resistant surface treatment, the result being called the X-15A-2. It first flew June 28, 1964, and eventually reached a speed of 7,274 km/h (4,520 mi/h or 2,021 m/s). The altitudes attained by the X-15 remained unsurpassed by any piloted aircraft except the Space Shuttle until the 3rd spaceflight of SpaceShipOne in 2004. The speeds and altitudes have, also, frequently been exceeded by unpiloted air-launched rockets, such as the Pegasus rocket which has carried several satellites all the way into orbit. The widely reported record achieved by the diminutive X-43A scramjet testbed on November 16, 2004 of nearly Mach 10 (10,621 km/h or 2.95 km/s) at 95,000 ft (29 km) is only a record for an air-breathing jet engine.
Text : Wikipedia, the free encyclopedia
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The X-15 and Hypersonics
The 1950s was definitely the decade of speed as far as U.S. aeronautical research was concerned the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA) were convinced that the key to dominating the skies was to fly faster than the opponent. The X-1 experimental aircraft broke the sound barrier in 1947. The Navy D-558-II ("D-558 Dash Two") reached Mach 2 on November 20, 1953. Soon other aircraft were reaching Mach 2.44 (1,650 miles per hour, or 2,655 kilometers per hour) and Mach 3.196 (2,094 miles per hour, or 3,370 kilometers per hour). These high speeds presented new challenges to aircraft designers.
People who study how air moves around an aircraft are called aerodynamicists. Although one of their most useful tools for decades was the wind tunnel, they could not always provide the kind of data that they needed. By the 1950s, there was virtually no way to simulate with a wind tunnel how air flowed around an aircraft at many times the speed of sound. Aerodynamicists had theoretical models (in this case a "model" is a set of equations that predict how certain shapes will act at certain airspeeds), but in order to confirm the models, they would have to actually fly an aircraft at that speed.
In 1952, the NACA established a goal of conducting research on aircraft capable of flying at speeds between Mach 4 and Mach 10 and at altitudes between 12 and 50 miles (19 and 80 kilometers). This speed range was called "hypersonic." On September 30, 1955, North American Aviation was awarded a contract to develop an aircraft to conduct this research. The aircraft was designated the X-15. The X-15 developed numerous technologies associated with high-speed flight. These technologies were later incorporated into aviation, missile, and space programs. Of all the X-plane programs (and there have been dozens), the X-15 is generally considered the most successful because it flew the longest and greatly expanded the boundaries of flight research.
The X-15 had a long fuselage with short stubby wings and an unusual tail configuration. A Reaction Motors, Inc. XLR99 rocket engine generating 57,000 pounds (253,549 newtons) of thrust powered the aircraft. This engine used ammonia and liquid oxygen for propellant and hydrogen peroxide to drive the high-speed turbopump that pumped fuel into the engine. This rocket could be throttled like an airplane engine and was the first such throttleable engine that was "man-rated" or declared safe to operate with a human aboard.
Because the X-15 would operate in extremely thin air at high altitudes, conventional mechanisms for controlling the aircraft were not sufficient, and the aircraft was equipped with small rocket engines in its nose for steering. This was the first aircraft to use such a steering method, although it was also in development for the Mercury spacecraft at the same time. The X-15 designers anticipated that their biggest problem would be the intense heat that the aircraft would encounter due to the friction of air over its skin. The upper fuselage would reach temperatures over 460 degrees Fahrenheit (F) (238 degrees Celsius [C]). But other parts of the aircraft would reach temperatures of a whopping 1,230 degrees F (666 degrees C) and the nose would reach a temperature of 1,240 degrees F (671 degrees C). Designers chose to use a high-temperature alloy known as Inconel X, which unlike most materials, remained strong at high temperatures. It was a difficult material to work with. The wings of the X-15 were constructed of Inconel X skins over titanium frames and were bolted to the fuselage instead of being mounted to a main spar as was customary.
The X-15 first flew on June 8, 1959, on a glide flight. It was dropped from under the wing of a specially modified B-52 "mothership." The first powered flight took place on September 17. Once the X-15 fell clear of the B-52, pilot Scott Crossfield ignited the rocket engine and flew to a relatively pokey Mach .79. But the X-15 was soon traveling many times the speed of sound. The X-15 continued flying until October 24, 1968, making 199 total flights among three aircraft and establishing many records.
During its early years of flight, the X-15 confirmed the hypersonic models developed by U.S. aerodynamicists. These models were later used to design other missiles and spacecraft, such as the Space Shuttle. Because of its ability to reach such high speeds and altitudes, the X-15 was a useful test platform for other research experiments. After its initial test flights it began carrying micrometeorite collection pods and ablative heat shield samples for the Apollo program and various other experiments. For approximately the last six years of its operation, the X-15 was not really conducting the missions of an X-plane (expanding the frontiers of flight), but was supporting all kinds of technology programs that required its high speed.
The X-15 pioneered the use of various materials for high-speed aircraft and spacecraft, as well as the techniques to construct them. Its rocket engine was also important for the development of later rocket engines, such as the Space Shuttle Main Engine. Inconel X was used for some key parts of the Space Shuttle structure.
The X-15 was also the first aircraft to make extensive use of a "man-in-loop" simulator to explore how the aircraft would perform in flight. A pilot would sit in the simulator on the ground and practice his procedures and try to determine what the plane would do when he later flew it. This was a new use for simulators and is now common in all experimental programs. Today, long before an aircraft begins flying, pilots and engineers are using simulators to evaluate its flying characteristics on the ground.
The X-15 is widely considered by many aerospace engineers to be the most successful experimental aircraft ever built. Of the two remaining X-15s, one is in the National Air and Space Museum in Washington, D.C., and the other is in the Air Force Museum in Dayton, Ohio.
Text by: Dwayne A. Day
And these, from owensarchive.com:
High-altitude contrails frame the B-52 mothership as it carries the X-15 aloft for a research flight on 13 April 1960 on Air Force Maj. Robert M. White's first X-15 flight. The X-15s were air-launched so that they would have enough rocket fuel to reach their high speed and altitude test points. For this early research flight, the X-15 was equipped with a pair of XLR-11 rocket engines until the XLR-99 was available.
NASA B-52, Tail Number 008, is an air launch carrier aircraft, "mothership," as well as a research aircraft platform that has been used on a variety of research projects. The aircraft, a "B" model built in 1952 and first flown on June 11, 1955, is the oldest B-52 in flying status and has been used on some of the most significant research projects in aerospace history.
X-15 (56-6672) research aircraft is secured by ground crew after landing on Rogers Dry Lakebed. The work of the X-15 team did not end with the landing of the aircraft. Once it had stopped on the lakebed, the pilot had to complete an extensive post-landing checklist.
Post-landing checklist involved recording instrument readings, pressures and temperatures, positioning switches, and shutting down systems. The pilot was then assisted from the aircraft, and a small ground crew depressurized the tanks before the rest of the ground crew finished their work on the aircraft.
Hangar 4802 at the NASA Flight Research Center in 1966. Aircraft on left include (left to right): HL-10, M2-F2, M2-F1, F-4A, F5D-1, F-104 (barely visible) and C-47. Aircraft on the right side (left to right) include: X-15-1 (56-6670), X-15-3 (56-6672), and X-15-2 (56-6671).
Hangar 4802 had been the main hangar at the Flight Research Center (FRC--now the Dryden Flight Research Center, Edwards, CA) and before that, the High-Speed Flight Station, since 1954. During 1966, the two main flight research projects at the FRC were the lifting bodies (including the M2-F1, M2-F2, and HL-10) and the X-15.
Both the HL-10 and X-15 shown here parked beside one another on the NASA ramp in 1966, underwent modifications. The X-15 No. 2 had been damaged in a crash landing in November 1962. Subsequently, the fuselage was lengthened, and it was outfitted with two large drop tanks. These modifications allowed the X-15A-2 to reach the speed of Mach 6.7.
On the HL-10, the stability problems that appeared on the first flight at the end of 1966 required a reshaping of the fins' leading edges to eliminate the separated airflow that was causing the unstable flight. By cambering the leading edges of the fins, the HL-10 team achieved attached flow and stable flight.
This photo shows one of the four attempts NASA made launching two X-15 aircraft in one day. This attempt occurred November 4, 1960. None of the four attempts was successful, although one of the two aircraft involved in each attempt usually made a research flight. In this case, Air Force pilot Robert A. Rushworth flew X-15 #1 on its 16th flight to a speed of Mach 1.95 and an altitude of 48,900 feet.
NASA research pilot Bill Dana is seen here next to the X-15 #3 rocket-powered aircraft after a flight. William H. Dana is Chief Engineer at NASA's Dryden Flight Research Center, Edwards, California.
Formerly an aerospace research pilot at Dryden, Dana flew the F-15 HIDEC research aircraft and the Advanced Fighter Technology Integration F-16 aircraft. Dana flew the X-15 research airplane 16 times, reaching a top speed of 3,897 miles per hour and a peak altitude of 310,000 feet (almost 59 miles high).
Captain Joe Engle is seen here next to the X-15-2 (56-6671) rocket-powered research aircraft after a flight. Engle made 16 flights in the X-15 between October 7, 1963, and October 14, 1965. Three of the flights, on June 29, August 10, and October 14, 1965, were above 50 miles, qualifying him for astronaut wings under the Air Force definition. (NASA followed the international definition of space as starting at 62 miles.)
Engle was selected as a NASA astronaut in 1966, making him the only person who had flown in space before being selected as an astronaut. First assigned to the Apollo program, he served on the support crew for Apollo 10, and then as backup lunar module pilot for Apollo 14. In 1977, he was commander of one of two crews who were launched from atop a modified Boeing 747 in order to conduct approach and landing tests with the Space Shuttle Enterprise.
NASA research pilot Milt Thompson stands next to the X-15 #3 ship after a research flight. Milton 0. Thompson was a research pilot, Chief Engineer and Director of Research Projects during a long career at the NASA Dryden Flight Research Center.
Thompson was hired as an engineer at the Flight Research Facility on March 19, 1956, when it was still under the auspices of NACA. He became a research pilot on May 25, 1958.
Thompson was one of the 12 NASA, Air Force, and Navy pilots to fly the X-15 rocket-powered research aircraft between 1959 and 1968. He began flying X-15s on October 29, 1963. He flew the aircraft 14 times during the following two years, reaching a maximum speed of 3723 mph (Mach 5.42) and a peak altitude of 214,100 feet on separate flights.
X-15 aircraft in flight over the desert December 20, 1961. Ship #3 made 65 flights during the program, attaining a top speed of Mach 5.65 and a maximum altitude of 354,200 feet. Only 10 of the 12 X-15 pilots flew Ship #3, and only eight of them earned their astronaut wings during the program.
Robert White, Joseph Walker, Robert Rushworth, John "Jack" McKay, Joseph Engle, William "Pete" Knight, William Dana, and Michael Adams all earned their astronaut wings in Ship #3. Neil Armstrong and Milton Thompson also flew Ship #3. In fact, Armstrong piloted Ship #3 on its first flight, on 20 December 1961
NASA test pilot Neil Armstrong wearing space suit is seen here next to the X-15 ship #1 (56-6670) after a high speed research flight. Neil A. Armstrong joined the National Advisory Committee for Aeronautics (NACA) at the Lewis Flight Propulsion Laboratory (later NASA’s Lewis Research Center, Cleveland, Ohio, and today the Glenn Research Center) in 1955.
Later that year, he transferred to the NACA’s High-Speed Flight Station (today, NASA’s Dryden Flight Research Center) at Edwards Air Force Base in California as an aeronautical research scientist and then as a pilot, a position he held until becoming an astronaut in 1962.
Armstrong was one of nine NASA astronauts in the second class to be chosen, as a research pilot he served as project pilot on the F-100A and F-100C aircraft, F-101, and the F-104A. He also flew the X-1B, X-5, F-105, F-106, B-47, KC-135, and Paresev.
Neil Armstrong left Dryden with a total of over 2450 flying hours. He was a member of the USAF-NASA Dyna-Soar Pilot Consultant Group before the Dyna-Soar project was cancelled, and studied X-20 Dyna-Soar approaches and abort maneuvers through use of the F-102A and F5D jet aircraft.
NASA research pilot Bill Dana is seen here wearing space suit, next to the X-15 rocket-powered aircraft after flight. William H. Dana is Chief Engineer at NASA's Dryden Flight Research Center, Edwards Air Force Base.
Formerly an aerospace research pilot at Dryden, Dana flew the F-15 HIDEC research aircraft and the Advanced Fighter Technology Integration/F-16 aircraft. Dana flew the X-15 research airplane 16 times, reaching a top speed of 3,897 miles per hour and a peak altitude of 310,000 feet (almost 59 miles high).
NASA X-15 test pilots, left to right; Air Force Captain Joseph H. Engle, Air Force Major Robert A. Rushworth, NASA pilot John B. "Jack" McKay, Air Force pilot William J. "Pete" Knight, NASA pilot Milton O. Thompson, and NASA pilot Bill Dana.
Of their 125 X-15 flights, 8 were above the 50 miles that constituted the Air Force's definition of the beginning of space "Engle 3, Dana 2, Rushworth, Knight, and McKay one each." NASA used the international definition of space as beginning at 62 miles above the earth. Color photograph.
This photo shows the X-15 cockpit and was unique for many reasons, including the fact that it had two types of controls for the pilot.
For flight in the dense air of the usable atmosphere, the X-15 used conventional aerodynamic controls such as rudder surfaces on the vertical stabilizers to control yaw and movable horizontal stabilizers to control pitch when moving in synchronization or roll when moved differentially.
For flight in the thin air outside of the appreciable Earth's atmosphere, the X-15 used a reaction control system. Hydrogen peroxide thrust rockets located on the nose of the aircraft provided pitch and yaw control. Those on the wing provided roll control.
The conventional aerodynamic controls used a stick, located in the middle of the floor, and pedals. The reaction control system used a side arm controller, seen in this photo on the left.
X-15 #2 (56-6671) launches away from the B-52 mothership with its rocket engine ignited. The white patches near the middle of the ship are frost from the liquid oxygen used in the propulsion system, although very cold liquid nitrogen was also used to cool the payload bay, cockpit, windshields and nose.
The X-15-1(56-6670) rocket powered research aircraft as it was rolled out in 1958. At this time, the XLR-99 rocket engine was not ready, so to make the low-speed flights (below Mach 3), the X-15 team fitted a pair of XLR-11engines into the modified rear fuselage. These were basically the same engines used in the X-1 aircraft.
The second X-15 rocket plane (56-6671) is shown with two external fuel tanks which were added during its conversion to the X-15A-2 configuration in the mid-1960's. After receiving an ablative coating to protect the craft from the high temperatures associated with high-Mach-number supersonic flight, the X-15A-2 was then covered with a white sealant coat. NASA Dryden Flight Research Center, Edwards AFB, 1965.
NASA Test pilot Major Robert M. White is seen here next to the X-15 aircraft after a research flight. White was one of the initial pilots selected for the X-15 program, representing the Air Force in the joint program with NASA, the Navy, and North American Aviation.
Between 13 April 1960 and 14 December 1962, he made 16 flights in the rocket-powered aircraft. He was the first pilot to fly to Mach 4, 5, and 6 (respectively 4, 5, and 6 times the speed of sound). He also flew to the altitude of 314,750 feet on 17 July 1962, setting a world altitude record.
This was 59.6 miles, significantly higher than the 50 miles the Air Force accepted as the beginning of space, qualifying White for astronaut wings.
Air Force test pilot William J. "Pete" Knight is seen here in front of the X-15A-2 aircraft (56-6671). Pete Knight made 16 flights in the X-15, and set the world unofficial speed record for fixed wing aircraft, 4,520 mph (mach 6.7), in the X-15A-2. He also made one flight above 50 miles, qualifying him for astronaut wings.
The X-15 rocket-powered aircraft was taken aloft under the wing of a B-52. Because of the large fuel consumption, the X-15 was air launched from a B-52 mothership aircraft at 45,000 ft and a speed of about 500 mph. This was one of the early powered flights using a pair of XLR-11 engines (until the XLR-99 became available).
After receiving a full scale ablative coating to protect the craft from the high temperatures associated with high-Mach-number supersonic flight, the X-15A-2 (56-6671) rocket powered research aircraft was then covered with a white sealant coat and mounted with additional external fuel tanks. This ablative coating and sealant would help the X-15A-2 aircraft reach the record speed of 4,520 mph (Mach 6.7).
X-15 rocket powered aircraft was taken aloft under the wing of a B-52. Because of the large fuel consumption, the X-15 was air launched from a B-52 aircraft at 45,000 ft and a speed of about 500 mph. This photo was taken from one of the observation windows in the B-52 shortly before dropping the X-15.
North American Aviation X-15 followed by a Lockheed F-104A Starfighter chase plane, the North American X-15 ship #3 (56-6672) sinks toward touchdown on Rogers Dry Lake following a research flight. In the foreground is green smoke, used to indicate wind direction.
The F-104 chase pilot joined up with the X-15 as it glided to the landing. The chase pilot was there to warn the X-15 pilot of any problems and to call out the altitude above the lakebed. F-104 aircraft were also used for X-15 pilot training to simulate the landing characteristics of the rocket-powered airplane, which landed without engine power since the rocket engine had already burned all of its propellant before the landing.
The F-104s could simulate the steep descent of the X-15 as it glided to a landing, they did this by extending the landing gear and speed brakes while setting the throttle to idle.
The X-15 ship #3 (56-6672) is seen here on the lakebed at the Edwards Air Force Base, Edwards, California. Ship #3 made 65 flights during the program, attaining a top speed of Mach 5.65 and a maximum altitude of 354,200 feet.
Only 10 of the 12 X-15 pilots flew Ship #3, and only eight of them earned their astronaut wings during the program. Robert White, Joseph Walker, Robert Rushworth, John "Jack" McKay, Joseph Engle, William "Pete" Knight, William Dana, and Michael Adams all earned their astronaut wings in Ship #3. Neil Armstrong and Milton Thompson also flew Ship #3. In fact, Armstrong piloted Ship #3 on its first flight, on 20 December 1961
The X-15-3 (56-6672), seen here on the lakebed at Edwards Air Force Base, Edwards, California, was a rocket-powered aircraft 50 ft long with a wingspan of 22 ft. It was a missile-shaped vehicle with an unusual wedge-shaped vertical tail, thin stubby wings, and unique side fairings that extended along the side of the fuselage.
The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch. The XLR-99 rocket engine, manufactured by Thiokol Chemical Corp., was pilot controlled and was capable of developing 57,000 lb of thrust. North American Aviation built three X-15 aircraft for the program.
On 9 November 1962, an engine failure forced Jack McKay, a NASA research pilot, to make an emergency landing at Mud Lake, Nevada, in the second X-15 (56-6671); its landing gear collapsed and the X-15 flipped over on its back. McKay was promptly rescued by an Air Force medical team standing by near the launch site, and eventually recovered to fly the X-15 again.
Test pilot Jack McKay injuries were more serious than at first thought, eventually forced his retirement from NASA. The aircraft was sent back to the manufacturer, where it underwent extensive repairs and modifications. It returned to Edwards in February 1964 as the X-15A-2, with a longer fuselage (52 ft 5 in) and external fuel tanks.
A series of ground and in-flight accidents occurred during the X-15's contractor program, fortunately without injuries or even greatly delaying the program. On 5 November 1959 a small engine fire started and forced pilot Scott Crossfield to make an emergency landing on Rosamond Dry Lake.
The X-15, not designed to land with fuel, came down with a heavy load of propellants and broke its back, grounding this particular X-15, ship #2 (56-6671), for three months.
This photo shows the X-15A-2 (56-6671) on a research flight with a ramjet engine attached to the bottom of its wedge-shaped vertical tail.
One of the experiments planned for the X-15A-2 involved tests of a functional ramjet at speeds above Mach 5. This photo was taken with a dummy ramjet. On this research flight, the X-15A-2 did not carry the two drop tanks used on its Mach 6.7 flight. It also had not yet been covered with an ablative coating.
The X-15A-2 made several flights with the dummy ramjet, leading to the record Mach 6.7 flight on October 3, 1967. Delays in producing the operational ramjet, aerodynamic heating damage to the aircraft during the record flight (despite the ablative coating), and the end of the X-15 program in 1968 resulted in no flights with the actual ramjet.
The X-15 aircraft, ship #1 (56-6670), sits on the lakebed early in its illustrious career of high speed flight research. The X-15 was a rocket-powered aircraft 50 ft long with a wingspan of 22 ft. It was a missile-shaped vehicle with an unusual wedge-shaped vertical tail, thin stubby wings, and unique side fairings that extended along the side of the fuselage. The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch.
X-15 test pilots, left to right; Air Force Captain Joseph H. Engle, Air Force Major Robert A. Rushworth, NASA pilot John B. "Jack" McKay, Air Force pilot William J. "Pete" Knight, NASA pilot Milton O. Thompson, and NASA pilot Bill Dana.
Of their 125 X-15 flights, 8 were above the 50 miles that constituted the Air Force's definition of the beginning of space "Engle 3, Dana 2, Rushworth, Knight, and McKay one each." NASA used the international definition of space as beginning at 62 miles above the earth.
NASA test pilots Milton O. Thompson, William H. "Bill" Dana, and John B. "Jack" McKay are seen here in front of the #2 X-15 (56-6671) rocket-powered research aircraft. Among them, the three NASA research test pilots made 59 flights in the X-15 (14 for Thompson, 16 for Dana, and 29 for McKay).
X-15 rocket-powered research aircraft being carried aloft under the wing of its B-52 mothership. The X-15 was air launched from the B-52 so the rocket plane would have enough fuel to reach its high speed and altitude test points.
NASA B-52, Tail Number 008, is an air launch carrier aircraft, "mothership," as well as a research aircraft platform that has been used on a variety of research projects. The aircraft, a "B" model built in 1952 and first flown on June 11, 1955, is the oldest B-52 in flying status and has been used on some of the most significant research projects in aerospace history.
The X-15 (56-6670), seen here on the lakebed at Edwards Air Force Base, Edwards, California. This X-15 was still equipped with two XLR-11 engines designed and built by Reaction Motors, pending installation of the XLR-99 engine, which first flew on November 15, 1960.
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About the X-15B:
From astronautix.com:
American manned spacecraft. Study 1958. North American's proposal for the Air Force initial manned space project was to extend the X-15 program. The X-15B was a 'stripped' X-15A with an empty mass of 4500 kg.
It would use a three-stage Navaho-derived launch vehicle to achieve a single orbit with an apogee of 120 km and a perigee of 75 km.
In the aftermath of Sputnik 2, the Air Force quietly asked its leading contractors for "unsolicited" proposals for manned spacecraft that could be quickly executed and beat the Russians in putting a man in orbit. Harrison Storms of North American conceived of a bold move to get an American into space as quickly as possible, in order to beat the Russians in the next obvious step of the space race. North American had a warehouse full of partially-completed G-38 boosters for the just-canceled Navaho missile program. Storms threw together a proposal to cluster them four of them in order to launch an orbital version of the company's X-15 manned rocketplane. He took the proposal to the Air Research and Development Command (ARDC) at Wright Field in November 1957.
Storms' X-15B was a 'stripped' X-15A with an empty mass of 4500 kg. The launch vehicle consisted of 4 x G-26 Navaho booster stages plus the X-15B's own XLR-99 engine. These would allow the X-15B to achieve a single orbit with an apogee of 120 km and a perigee of 75 km. Due to the low perigee and aerodynamics of the X-15, no retrorocket was required, although the X-15's restartable engine could be used if necessary. Using its cross range capability of about 800 to 1,000 km, the X-15 would ditch in the Gulf of Mexico. The heat shield would consist of beryllium oxide and Rene 41 alloy. The pilot would eject and land by parachute, with the aircraft being lost. The spacecraft had a ballistic coefficient (W/CdA) of 250 kg per square meter. It was expected that a first manned orbital flight could be achieved 30 months after a go-ahead at a cost of $ 120 million.
The general in charge of ARDC found it interesting but said there was no official requirement to orbit a man in space. But the political pressure to do something in response to Sputnik mounted, and a secret conference was held at on 29-31 January 1958 at Wright field. Eleven aircraft and missile firms outlined for the Air Force and NACA observers the various classified proposals for a manned satellite vehicle that they had submitted during November and December 1957.
The ARDC boiled down the 11 proposals to the three that had the best chance of quick realization - the X-15B, acceleration of the nascent program for the X-20 Dynasoar winged space glider, or one of the simple ballistic capsule designs, boosted by an existing launch vehicle. On 27 February they took these straight to Curtis LeMay, head of the Strategic Air Command, who's main comment was, "Where's the bomb bay?" Nevertheless, he instructed ARDC to select one of the concepts and submit a detailed plan for an Air Force man-in-space program as soon as possible.
On 10-12 March ARDC held a conference at its Ballistic Missile Division (BMD) in Los Angeles of more than 80 rocket, aircraft, and human-factors specialists. The objective was to reach agreement on a plan to get a man-in-space - soonest - in accordance with LeMay's orders. The BMD itself had its sights set on Project Lunex, a long term plan to establish an Air Force base on the moon before 1970. Unfortunately for Storms, the consensus at the conference was that the "quick and dirty" approach would consist of a simple ballistic capsule using parachutes for a water landing, weighing around 1300 kg. This would be 1.8 m in diameter and 2.4 m long. The capsule would be completely automated - the human-factors people felt there was no certainty that a pilot could function under the stresses of space flight. This last point seemed to rule out the piloted X-15B approach.
ARDC continued on the Manned-in-Space-Soonest project into August 1958, and in June Storms had even been told he would receive the contract for the manned spacecraft. But meanwhile, President Eisenhower and the Congress had created a new civilian Agency to take on the Soviet spaceflight challenge - NASA. And Max Faget, the lead spacecraft designer at NASA, was one of the originators of the ballistic capsule concept. The USAF budget for the initial manned spacecraft was transferred to NASA, and with it evaporated Storms' expected contract, and the X-15B. The contract for what NASA renamed project Mercury would go to McDonnell.
This was not quite the end of the orbital X-15. It was known that North American later proposed use of four Titan I booster stages in place of the Navaho boosters.
Note
The notes of NACA engineer Clarence A. Syvertson from this meeting indicate that four Navaho G-26 boosters would be used. The biography of Harrison Storms indicates that G-38 boosters were proposed. A quick calculation showed that four G-26 boosters could not get the X-15 into orbit; G-38 boosters just about could. So in this case physics and the memory of Storms trump the contemporaneous notes. It was likely in any case that the boosters proposed were derived from, but not identical to the G-26 or G-38 boosters.
A drawing also emerged of an X-15 atop a single G-26 booster. It was likely that a program of slow build-up to orbital speeds, using Navaho surplus assets, was proposed.
Characteristics
Crew Size: 1. Spacecraft delta v: 2,450 m/s (8,030 ft/sec).
Gross mass: 13,500 kg (29,700 lb).
Unfuelled mass: 4,500 kg (9,900 lb).
Height: 15.00 m (49.00 ft).
Span: 6.80 m (22.30 ft).
Thrust: 262.45 kN (59,000 lbf).
Specific impulse: 276 s.
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Associated Countries •USA
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Associated Engines •XLR99 Thiokol Lox/Ammonia rocket engine. 262.4 kN. Out of production. Isp=276s. The first large, man-rated, throttleable, restartable liquid propellant rocket engine, boosted the X-15A. First flight 1959. More...
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See also •Low earth orbit
•Man-In-Space-Soonest The beginning of the Air Force's Man-In-Space-Soonest program has been traced back to a staff meeting of General Thomas S Power, Commander of the Air Research and Development Command (ARDC) in Baltimore on 15 February 1956. Power wanted studies to begin on manned space vehicles that would follow the X-15 rocketplane. These were to include winged and ballistic approaches - the ballistic rocket was seen as being a militarily useful intercontinental troop and cargo vehicle. More...
•Manned
•Manned spacecraft
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Associated Manufacturers and Agencies •USAF American agency overseeing development of rockets and spacecraft. United States Air Force, USA. More...
•North American American manufacturer of rockets, spacecraft, and rocket engines. North American, Palmdale, El Segundo. Downey, CA, USA More...
•USAF American agency. USAF, USA. More...
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Associated Propellants •Lox/Ammonia
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Bibliography •Baker, David, The History of Manned Spaceflight, Crown, New York, 1981.
•Jenkins, Dennis R,, Space Shuttle: The History of the National Space Transportation System : The First 100 Missions, Third edition, Voyageur Press, 2001.
•Swenson, Grimwood, Alexander, Charles C, This New Ocean, Government Printing Office, 1966. Web Address when accessed: http://www.hq.nasa.gov/office/pao/History/SP-4201/cover.htm.
•Grimwood, James M., Project Mercury: A Chronology, NASA Special Publication-4001.
•Gray, Mike, Angle of Attack: Harrison Storms and the Race to the Moon, Penguin Reprint edition, 1994.
More, from friends-partners.org.:
X-15B - Orbital X-15 proposed for Project 7969
Credit: (c) Mark Wade. 9,079 bytes. 211 x 480 pixels.
X-15B
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Class: Manned. Type: Spacecraft. Nation: USA. Agency: USAF. Manufacturer: North American.
North American's proposal for the Air Force initial manned space project was to extend the X-15 program. The X-15B was a 'stripped' X-15A with an empty mass of 4500 kg. It would use a three-stage Navaho-derived launch vehicle to achieve a single orbit with an apogee of 120 km and a perigee of 75 km. The launch vehicle consisted of 4 x G-26 Navaho booster stages plus the X-15B's own XLR-99 engine. Due to the low perigee and aerodynamics of the X-15, no retrorocket was required, although the X-15's restartable engine could be used if necessary. Using its cross range capability of about 800 to 1,000 km, the X-15 would ditch in the Gulf of Mexico. The heat shield would consist of beryllium oxide and Rene 41 alloy. The pilot would eject and land by parachute, with the aircraft being lost. The spacecraft had a ballistic coefficient (W/CdA) of 250 kg per square meter. It was expected that a first manned orbital flight could be achieved 30 months after a go-ahead at a cost of $ 120 million.
And this:
X-15B: pursuit of early orbital human spaceflight.
[ILLUSTRATION OMITTED]
The North American X-15 hypersonic research aircraft was among the most successful of all the X-series. A cooperative research program among the U.S. Navy, Air Force and the National Aeronautics and Space Administration (NASA), the X-15 exceeded all expectations as it expanded the known flight envelope. When the program ended after 199 flights, the U.S. was well along the path towards operational space vehicles and human spaceflight.
An orbital version, variously called the Advanced X-15, Orbital X-15, or X-15B, began in part with the original proposals for the X-15 calling for a two-seat version. The concept endured at a low level for several years, reaching a peak of interest in 1958-1959. When mentioned at all subsequently, the X-15B has been relegated to little more than a footnote, and understood as the logical progression for much of the X-series aircraft pushing higher, faster and farther. (1)
Justifying the X-15B as simply pushing the flight envelope outwards is as misleading as making the same argument for MERCURY. Higher, faster and farther might be felt as an imperative or a characterization of aviation's evolution, but it was not the end in itself. The orbital X-15 answered very different motivations.
The Role of Human Presence--1950s Style
The U.S. space program began in the military long before NASA's 1958 creation. The military developed the sine qua non of any space program: the launch vehicles. The military also had all the plans, concepts and strategies receiving any funding (however meager) in the early 1950s. "Artificial moons" were so radical that many of the senior military leadership only vaguely understood them. Especially in the Air Force, experience with robotic aircraft colored any understanding of robotic spacecraft.
Tenuous attempts in World War II using robotic (now called unpiloted) aircraft showed serious limitations. Lessons learned from these attempts exposed the real bias: human presence caused operational utility. This remained the military consensus for decades after World War II. Robotic aircraft of the 1950s, such as the SNARK, REGULUS, MATADOR and MACE, were akin to but far less capable than today's cruise missiles. All suffered from rudimentary technology inadequate to the senior military leadership demands for effective and reliable weapons. Progress was erratic. These early programs indicated to the military leadership that they held some interesting ideas, but were hardly reliable or operational.
On October 5, 1954, the National Advisory Committee on Aeronautics' (NACA) High-Speed Flight Station executive committee faced the final decision to proceed with a hypersonic research aircraft. Lockheed's Clarence "Kelly" Johnson alone favored robotic aircraft to explore the flight regimes proposed for the X-15. He firmly...
Read more: http://vlex.com/vid/x-15b-pursuit-early-orbital-spaceflight-56379293#ixzz1OBKpka6W
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Specification
Total Mass: 4,500 kg.
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Bibliography:
26 - Baker, David, The History of Manned Spaceflight, Crown, New York, 1981.
483 - Grimwood, James M., Project Mercury: A Chronology, NASA Special Publication-4001.
And lastly, this, from findarticles.com:
X-15B: pursuit of early orbital human spaceflight
by L. Parker Temple, III
The North American X-15 hypersonic research aircraft was among the most successful of all the X-series. A cooperative research program among the U.S. Navy, Air Force and the National Aeronautics and Space Administration (NASA), the X-15 exceeded all expectations as it expanded the known flight envelope. When the program ended after 199 flights, the U.S. was well along the path towards operational space vehicles and human spaceflight.
An orbital version, variously called the Advanced X-15, Orbital X-15, or X-15B, began in part with the original proposals for the X-15 calling for a two-seat version. The concept endured at a low level for several years, reaching a peak of interest in 1958-1959. When mentioned at all subsequently, the X-15B has been relegated to little more than a footnote, and understood as the logical progression for much of the X-series aircraft pushing higher, faster and farther. (1)
Justifying the X-15B as simply pushing the flight envelope outwards is as misleading as making the same argument for MERCURY. Higher, faster and farther might be felt as an imperative or a characterization of aviation's evolution, but it was not the end in itself. The orbital X-15 answered very different motivations.
The Role of Human Presence--1950s Style
The U.S. space program began in the military long before NASA's 1958 creation. The military developed the sine qua non of any space program: the launch vehicles. The military also had all the plans, concepts and strategies receiving any funding (however meager) in the early 1950s. "Artificial moons" were so radical that many of the senior military leadership only vaguely understood them. Especially in the Air Force, experience with robotic aircraft colored any understanding of robotic spacecraft.
Tenuous attempts in World War II using robotic (now called unpiloted) aircraft showed serious limitations. Lessons learned from these attempts exposed the real bias: human presence caused operational utility. This remained the military consensus for decades after World War II. Robotic aircraft of the 1950s, such as the SNARK, REGULUS, MATADOR and MACE, were akin to but far less capable than today's cruise missiles. All suffered from rudimentary technology inadequate to the senior military leadership demands for effective and reliable weapons. Progress was erratic. These early programs indicated to the military leadership that they held some interesting ideas, but were hardly reliable or operational.
On October 5, 1954, the National Advisory Committee on Aeronautics' (NACA) High-Speed Flight Station executive committee faced the final decision to proceed with a hypersonic research aircraft. Lockheed's Clarence "Kelly" Johnson alone favored robotic aircraft to explore the flight regimes proposed for the X-15. He firmly believed in human presence for operational (that is, practical application) missions, as opposed to purely aerodynamic research. At the time, he was developing the U-2 spyplane and thinking ahead to hydrogen-fuelled hypersonic reconnaissance aircraft. (2) Perhaps he thought a robotic aircraft could answer specific questions related to hypersonic aircraft sooner than a piloted aircraft, facilitating the development of operational aircraft he had in mind. Everyone else believed human presence was mandatory. (3) NACA's associate director for research, Gus Crowley, summed up the majority view: the successful X-1 program owed much to its pilots, whose performance allowed accomplishment of things robotic aircraft could not do. (4) This reveals the mindset that truly useful and operational capabilities required human presence.
This was the mindset, then, in the earliest days of the military's (and hence the nation's) space program. Robotic devices were so limited, based on experience with robotic aircraft, that human presence would inevitably be needed to achieve any operational military capability.
What benefits might human presence provide? A contemporary list simultaneously contrasted perceived benefits of human presence versus robotic spacecraft technological shortfalls. Since human presence counteracted robotic spacecraft shortfalls, the list was considered a standard against which to measure military space progress in the 1950s:
Decision Making Capability
Robots cannot perform "rapid and accurate decision making ... by 'on the spot' assessment of the situation."
Command Control Capability
Humans understand and react faster than robot computational speeds.
Determination of Vehicle and Payload Status
Humans monitor the spacecraft's status in situ, whereas robots require relay to the ground for processing.
Post-Launch Changes in Mission Plan
Humans perform more flexibly and readily adapt to new missions.
Payload Redundancy
Humans can "augment certain payload functions ... in the event of payload subsystem breakdowns."
Mission Data Redundancy
Remote, unobserved sensors might not report accurately; human presence can verify or deny sensors' reports.
Mission Data Augmentation
Robotic sensors are specialized with limited capacity for recording data. Humans can take inputs from many sources and integrate a complete picture of a situation.
Recovery of On-Board Payload Data
For a spaceplane, the ability to choose a landing site is crucial to returning the mission's data. Pilots routinely do this.
Early Mission Termination and Recovery
Humans can determine when to return or extend the orbit. Robots might suffer, at any time, "mission termination based on on-board programming."
Accomplishment of Mission Details
Humans can adjust sensors to "optimize the gathering of mission data."
Subsystem Complexity
Humans are "a general-purpose subsystem with a general-purpose compute capability to store and analyze events." (5)
These claims about the value of human presence reflected Air Force doctrine drawn from decades of atmospheric flying. Air Force Headquarters personnel, lacking any basis for judgment without actual human spaceflight experience, accepted these claims. Artificial moons might provide important interim capabilities, but as was the case with the robotic aircraft, only human-piloted spaceplanes had operational utility.
Clearly, the bias towards human presence that also anticipated robotic spacecraft would not be very capable was soon overturned as the U.S. devoted considerable resources and its best minds to the space program. The bias, however, is important to consider when judging the initial push for making the X-15, or any piloted vehicle, into an orbital spacecraft.
With this contemporary expectation of the value of human presence, and to really place the X-15B in context, we next need to understand the context itself: the flurry of activity surrounding spaceplanes in the mid-1950s.
Higher, Faster and Farther?
Although interest in spaceplanes was long standing, serious studies of orbital spaceplanes and high-speed rocket aircraft skimming across the upper edges of the sensible atmosphere began right after World War II. These studies extrapolated the first operational rocket planes flown by the Germans during the war. Each of the Services had some variation under study at a very low level.
For instance, the Navy received a proposal from Douglas Aircraft for a third generation of its D-558 series of research aircraft in 1953. That rocket plane, later part of the Douglas proposal for the X-15 competition, was to achieve one million feet altitude and nearly orbital speed, later scaled back to a more modest 750,000 feet and Mach 9. However, the project remained a paper study eventually yielding to the X-15. (6)
Bell Aircraft Corporation submitted a seminal proposal to Wright Air Development Center (WADC) on April 17, 1952. The premier X-series aircraft developer had hired Walther Dornberger as a rocketry consultant. The World War II commandant of Peenemunde for development and launch of the V-1 and V-2 rockets, Dornberger had been Wernher von Braun's former superior officer. He pushed for manned hypersonic rocket-launched gliders based on the pre-World War II ideas of Eugen Sanger and his wife Irene Bredt. (7)
Bell examined air launch of its X-series aircraft to achieve orbit, and proposed a new operational manned bomber-missile, BOMI. WADC offered Bell a one-year study to advance the concept, and asked for two examinations--a suborbital, hypersonic version and an orbital version. Bell combined both into a phased development from suborbital to orbital flight. A year's effort showed little progress. Dornberger's constant lobbying kept BOMI alive. By his estimate, he eventually gave some 900 presentations to all sorts of audiences on BOMI and successor spaceplanes. (8) His politicking worked, because in April 1954, Bell received another small contract to study an advanced reconnaissance bomber concept, designated MX-2276. This version of BOMI resembled the suborbital vehicle of the first phase in the original WADC study. Like its more famous successor, the DYNA-SOAR--for its suborbital (dynamic soaring) flight regime-MX-2276 was a nuclear weapon delivery system that could do its own post-strike reconnaissance.
Reconnaissance was critically important at the time. Closure of the Soviet Union's borders created a desperate need for Western intelligence about Soviet intentions. (9) President Dwight D. Eisenhower chartered a Technological Capabilities Panel to examine preventing a Soviet surprise nuclear attack. Throughout 1954, this effort identified a number of critically important steps the nation had to take. Among these were the developments of the Lockheed U-2 spyplane and the CORONA satellite reconnaissance system. These programs were covert; that is, not merely classified but hidden with their existence unacknowledged.
Meanwhile, the threat of surprise attack remained palpable, and the Services went about trying to solve the problem. On January 4, 1955, Air Research and Development Command (ARDC), anticipating the release of a General Operating Requirement (GOR) then in final coordination, released System Requirement 12 for an advanced reconnaissance aircraft with 3,000 nautical mile range and a ceiling of 100,000 feet. A month later, Air Force Headquarters released its equivalent, higher-level GOR 12, to proceed under Weapon System 118P, the Special Reconnaissance System. By September 1955, Bell's support to WS-118P included further BOMI studies. (10)
Air Force studies of a more advanced reconnaissance-bomber began in March 1956. The Hypersonic Weapon And Research and Development System (HYWARDS) was to achieve Mach 12 flight, twice that of the X-15 then on the drawing boards. (11)
Also, Bell got another contract for a highly advanced U-2 follow-on called BRASS BELL, Reconnaissance System 459L. Two months later, ARDC released System Requirement 126 for a I rocket-bomber, ROBO. ROBO allegedly included a reconnaissance version combining radar, infrared and optical scanning sensors, with relay of the sensor information to the ground while the ROBO was still in flight. (12)
Working cooperatively with NACA Langley for the aerodynamics research, the HYWARDS team soon realized that Mach 12 was insufficient, and that Mach 15 "was about the lowest speed for which an attractive military boost-glide mission could be defined." (13) From there, it seemed but a short step to Mach 18 (nearly orbital), which the group recommended in January 1957.
The plethora of spaceplanes formed a logical sequence, with HYWARDS to fly in 1965, BRASS BELL in 1968, followed by ROBO in 1974. (14) The proliferating concepts begged for consolidation. Air Force Deputy Chief of Staff (Development) Lt. Gen. Donald Putt reviewed the programs in January 1957. He thought BRASS BELL and HYWARDS were complementary and could be combined into a single, two-phase program. Furthermore, the X-15A would clearly provide nearly everything that could be learned from HYWARDS. Thus, in April 1957, Putt directed ARDC to combine all hypersonic research programs into a single development plan. (15)
NACA was also struggling with spaceplane concept diversity. For instance, NACA Ames and NACA Langley were at odds over the relative advantages of high and low lift-to-drag ratios. With only that one variable in mind, the range of studies and technologies was very large, indicating the considerable work necessary to explore various parts of the high speed flight regime. The Ames-Langley disagreements were technical, political and organizational. They serve to highlight the complexity of the issues involved in advancing spaceplanes. The range of options was simply so extensive that no single correct solution would readily reveal itself. (16)
Within this swirl in both NACA and ARDC, WADC produced a reasonable response to Putts direction for a unified development plan. HYWARDS, BRASS BELL and ROBO became three steps in an abbreviated program of development on December 21, 1957. (17) The combined effort was designated System 464L, named DYNA-SOAR I, with a projected first flight in July 1962. (18)
Strategic Air Command was the operational home for a variety of space uses, not the least of which were those embodied by DYNA-SOAR. Strategic Air Command's General Curtis E. LeMay intended DYNA-SOAR I as an advanced bomber, reconnaissance, air defense and space defense vehicle. (19) The DYNA-SOAR project elements convey a feeling for the broad range of capabilities that spaceplanes might accomplish: Manned Capsule Test; Boost-Glide Tactical Weapon Delivery; Boost-Glide Interceptor; Satellite Interceptor; Global Reconnaissance; and Global Bomber. (20)
Well aware of Putt's impending reorganization of spaceplanes, on the 54th anniversary of the first flight by the Wright Brothers, December 14, 1957, Air Force Chief of Staff General Thomas Dresser White announced "The missiles that are getting the headlines today are but one step in the evolution from aircraft to piloted spacecraft." (21)
Three days later, General White told the Senate Armed Services Committee that the X-15 "was a forerunner of the spacecraft ... [and] requires all the characteristics that one would find in a manned satellite to take care of the man." (22)
Human Orbital Spaceflight: Be First or Be Useful?
As rapidly as technology advanced, producing the first crucial operational space systems within two years of SPUTNIK (such as the CORONA, GRAB and POPPY reconnaissance satellites), the perception remained that these were really only interim capabilities awaiting routine human presence. The appropriate question, therefore, was not whether human spaceflight was needed, but rather, when it could be provided. Obviously, sooner was better than later.
By 1956, Air Force Project 7969, the Manned Ballistic Rocket Research System (23) was competing directly with the Army Ballistic Missile Agency's concept for a recoverable system on an Army missile (which became MERCURY). These bioastronautics research programs aimed at the minimum requirements to put humans in space and return them safely to Earth. These minimalist programs were not ends unto themselves, but simply necessary stepping-stones to operational missions.
The earliest design work on the X-15B dates from this period. Project 7969 was an important bridge between the minimalist and the robust, in that the proposals received from industry included both ballistic re-entry vehicles and winged vehicles. Perhaps the most interesting proposal was North American's proposal for an evolved X-15. Using staged boosters, the aircraft would orbit between 250,000 (perigee) and 400,000 feet (apogee). The first stage comprised three NAVAHO boosters; (24) another NAVAHO booster as a second stage; and the X-15B was the third. Its estimated gross liftoff weight was 720,000 pounds. Since the X-15B would have the same shape as the X-15A, nothing further was considered necessary for determining its flight characteristics. However, re-entry would only get the pilot to a safe ejection altitude, with the X-15 being lost in the Gulf of Mexico. North American's claimed cost and schedule were $120 million and 30 months. This was not very satisfactory, as it was a very expensive, one-time shot with no residual operational utility. (25) Nevertheless, the idea opened a door. After all, Putt's realization that most of HYWARDS' results could be gained from the X-15 meant that a version of the X-15 could be on a growth path to ROBO's operational mission, recently subsumed into DYNA-SOAR I. Nevertheless, making the X-15A withstand the expected re-entry heat and stress meant the X-15B would be a radically different vehicle in detail. (26)
Things stood there when the Soviets launched SPUTNIK on October 4, 1957, and the emphasis on space programs changed.
The VANGUARD project to launch an artificial moon during the International Geophysical Year, seen as the US' competitor to SPUTNIK, was far from success. The military were the only source of response to SPUTNIK. The problem was not a lack of alternatives, but choosing the right one.
As a champion for spaceplanes and a military space visionary, General LeMay, by that time the Air Force Vice Chief of Staff, took a personal interest in satellite and human spaceflight. LeMay announced the Man-In-Space-Soonest (MISS) project, causing the re-orientation of a number of ongoing studies and projects. Project 7969 got folded into MISS as one of the alternatives. (27)
Because of Project 7969's inclusion in MISS, MISS might sound like MERCURY. MERCURY began in the Army and eventually transferred to the new NASA after 1958. This was essentially the minimum system to put a human into space and safely return. Little weight or space remained for operational missions. This is not minimizing MERCURY's importance in demonstrating critical life support technologies and human spaceflight capabilities. However, MERCURY's limitations simply served to underscore the military objections to NASA's human spaceflight approach.
MISS' emphasis was on attaining operational capabilities from space at the earliest possible time. Interim steps might be needed to understand human physiology and life support systems, but the goal was operational uses. Competing ballistic reentry and lifting re-entry (spaceplane) concepts abounded, though with scanty data available for design. By 1957, Boeing's DYNA-SOAR embodied the Air Force's goal, providing a means to put military humans into space to perform militarily useful operational missions. DYNA-SOAR's urgently needed capabilities were a long way off, with its expected first flight in 1962. (28)
To grasp the range of alternatives, aside from the Air Force's own concepts, WADC held government-industry meetings January 29-31, 1958. In addition to discussing NACA projects, the Air Force invited 11 major contractors for an hour and a half apiece to brief concepts for achieving early human spaceflight. (29)
NACA Langley discussed Max Faget's research on a ballistic vehicle (basically the MERCURY capsule) and John V. Becker described work being done on a triangular planform that would use lift during re-entry to provide great flexibility in landing sites. After these informal discussions, the serious work got underway with the contractors. The final presentation was from North American Aviation, who described turning the X-15 aeronautical research aircraft into an operational (non-expendable) spaceplane. (30)
The MISS project alternatives grouped into three basic categories: ballistic vehicles, boost-glide vehicles and satelloids. Ballistic vehicles were shapes like ballistic missile nose cones intended to survive re-entry. The boost-glide vehicles would achieve nearly the same velocity, but would skim the upper reaches of the atmosphere as gliders at lower altitudes. Satelloids were basically gliders that would achieve minimum orbital velocity well above the atmosphere and use their aerodynamic features for re-entry. (31)
In February 1958, LeMay reviewed the alternative paths from the WADC conference. For the most part, the ballistic re-entry idea was the most competitive if the goal were limited to getting into space for no other point than having gotten there. That remained operationally unsatisfying because it could not be tied to some useful purpose. The Army's MERCURY capsule was one ballistic approach having no residual operational utility, but the Air Force had an alternative with an operational tie-in.
The SAMOS E-6 photoreconnaissance satellite required a very large re-entry capsule because both the film and the camera were to be recovered for reuse. (32) Unlike the blunt re-entry capsule of the familiar MERCURY design, the SAMOS capsule used a scaled-up General Electric RVX-2 missile re-entry nose cone. (33) Like CORONA, the SAMOS E-6 needed a plausible explanation for its launches. CORONA's cover story was the DISCOVERER research program. SAMOS used human spaceflight to explain the large size of its vehicles. Like MERCURY, the scaled-up RVX-2 was minimally large enough to fit a human inside, and was one alternative under Project 7969. (34) Also, the MISS version of the SAMOS capsule had little residual operational capability. In the case of SAMOS, however, the MISS version was secondary cover for an operational photoreconnaissance system. Since the human spaceflight story protected a classified mission, losing human spaceflight programs to NASA jeopardized the more important mission. Thus, in part, the Air Force objected, in support of the Army, to assigning human spaceflight responsibility to NASA. (35)
Such wingless, ballistic shapes had the advantage of simplicity, but serious disadvantages if anything other than basic bioastronautics was the goal. Bell's MISS boost-glide alternative design team pointed out that "wingless would only be a stunt." (36)
The second alternative path comprised boost-glide vehicles, including LeMay's favorite, DYNA-SOAR, undergoing initial source selection at that time.
Satelloid vehicles constituted the third alternative path, and included the X-15 that already had the first functional fu]l pressure space suit and flew at the edge of space. The X-15A program performed experiments inspired by the need for early DYNA-SOAR technology work. The X-15A was an ideal testbed for X-20 technology, but it also provided an apparent path to an earlier, though more limited, orbital capability. Making an orbital X-15 variant might be the fastest way to get real operational capability, while also resolving much of the flurry of proliferated spaceplane concepts. With an estimated much shorter (by half) development time than the boost-glide vehicles, the X-15B could also demonstrate critical technologies for DYNA-SOAR. (37)
While all three alternatives continued to move forward, each having merit for different reasons, the heat shortly got turned up on the ballistic reentry approach.
In April 1958, Maj. Gen. John B. Medaris, commander of the Army Ballistic Missile Agency, told Congress that he had recently asked for authority to launch a human on a JUPITER-C rocket and return him to Earth. He and Wernher von Braun claimed they could do this a year after direction to proceed. The Army and, after the concept's transfer to the new civilian space agency, NASA called it MERCURY. (38,39)
MERCURY was the fastest way to get humans into space and safely return them. Nearly as quickly, though, the X-15 might do far more in terms of residual capabilities. The MISS participants had all estimated between one and two and a half years to get a human into space and safely return (with two notable exceptions, whose estimates were more realistic at 5 years). Ballistic reentry shapes had the shortest development times. (40)
Nevertheless, the X-15 was designed to fly at the edge of the atmosphere at about one quarter of orbital speed. It already had to handle many of the physiological problems associated with orbital flight. The X-15 had shown it could handle sub-orbital flight, demonstrating its advanced capabilities on a regular basis. Orbital flight demanded long duration in space, so the X-15's life support system needed significant upgrading. Neither was its structure sufficiently durable to dissipate the heat of re-entry. Still, in theory, transforming the technologically mature X-15 into an operationally useful orbital spaceplane might be faster than any alternative.
Yet, by late 1957, interest in the orbital X-15B apparently evaporated, according to the sources that even discuss its existence. Hallion suggested that the MERCURY program overtook the orbital X-15B. However, MERCURY could not overcome its absence of residual operational utility. Jenkins claimed the X-15B drifted quietly away. (41) He assumed DYNA-SOAR (which became the X-20 in 1958) required too much attention by the Air Force for serious attention to be paid to the X-15B. Neither answer is entirely satisfactory.
What was the reality?
Instead of drifting quietly away, the X-15B studies became classified in 1957, allowing only spotty unclassified appearance of X-15B-related items. (42) Reasons exist to believe interest in the X-15B shifted from WADC to the Western Development Division, home of the military space program. (43) Lacking external visibility due to classification, the X-15B might seem to have received sporadic interest.
Instead, it the X-15B as a viable proposal intended to achieve human spaceflight early while retaining some operational capability had not gone away. Instead of simply paving the technological way for the DYNA-SOAR, the serious possibility arose that the X-15B might achieve orbit earlier, as the DYNA-SOAR ran into significant technological problems. DYNA-SOAR's truly unique problems resulted in its clearly falling behind, so it was not on the path to the earliest human spaceflight.
As the Air Force cast about for a suitable operational response to SPUTNIK, the X-15B might provide not only an early capability, but one that also possessed some operational utility--not as a replacement for DYNA-SOAR, but as an interim. Thus, as DYNA-SOAR slipped to the right, the X-15B retained interest. In addition to its anticipated earlier orbital flight possibility, the X-15B objectives to demonstrate and prove technologies for the DYNA-SOAR and satellites seemed to come at a low cost per spaceflight while retaining residual operational utility.
Had the X-15B become a competitor to the DYNA-SOAR? By November 1959, the X-15B studies advanced far enough to answer the key questions about making the X-15 orbital, also answering whether the X-15B had become the DYNA-SOAR's competitor.
Harrison Storms, North American's Los Angeles Division vice president and chief engineer, conducted the work. (44) Recently declassified final reports, SATURN/X-15 Flight Research Program Report, and its companion, Technical Summary Report, SATURN/X-15, at last give insight into the fate of the X-15B. (45)
X-15B Program Overview
The detailed studies of the X-15B's design and flight operations demonstrated the move from sub-orbital to orbital flight was larger than had been anticipated.
The X-15B program comprised four initial orbital flights. A "series of tests for attaining ... national objectives" would "make substantial contributions to the development of vast numbers of concepts and components envisioned for future space systems." (46) Building on the X-15 flight research program's capabilities, the X-15B added unique tests and experiments while slightly overlapping the MERCURY and CORONA/DISCOVERER programs. Four flight profiles exemplified the possible kinds of missions and planning. At the time, actual mission plans anticipated having to await the timing and progress from other programs such as MERCURY and CORONA/DISCOVERER.
The X-15B differed sufficiently from its flight research cousin that it needed qualification flight tests using the Boeing B-52 Stratofortress. Launch alternatives were air launch from a B-52 or the North American B-70 Valkyrie, contrasted with vertical launch aboard a Convair ATLAS or Martin TITAN rocket. Clusters of rockets were also a possibility, since the ATLAS and TITAN boosters alone were insufficiently powerful. These and other launch vehicle combinations reflected the emphasis on early human orbital spaceflight in the MISS program. By 1959, the studies had narrowed down the most direct, simplest and preferred method, which was the NASA SATURN.
Unlike its flight research forebear, the X-15B would deliver up to 5,000 pounds of payload with its pilot and test director for 48-hour missions. Clearly, that was more than a simple evolution of the X-15A.
Advanced did not necessarily imply completely new, however. For instance, in the X-15's proposal phase, each bidder had to address a Navy requirement for a second crewmember. (48) Also, for the January 1958 initial source selection of the System 464L, DYNA-SOAR 1, North American proposed a 15,000 pound-class vehicle based on the X-15B operating as a satelloid. (49) This idea recurred when bioastronautics requirements firmed up in 1960. (50) The X-15B studies kept such concepts alive.
Typical of the orbital research profiles was the first test carrying 4,068 pounds of equipment to 500,000 feet. During 32-orbits, the crew were to conduct tests such as:
Optical and radio telescopy
Infrared, radar and visual terrestrial observations
Human mobility in space
Biological research
Gravitational research.
The list illustrates the range of experiments and demonstrations, from theoretical scientific data gathering to practical applications with immediate utility.
The X-15B would fire retro-rockets during the 32d orbit, maneuvering for re-entry at 350,000 feet (as they thought) at 25,500 feet per second (fps). Twenty-five minutes of high-lift gliding flight would reduce these to 8,000 fps at 150,000 feet. The remainder of its flight to touchdown would mimic the X-15A, minimizing the number of unknowns in the X-15B flight profile. Thirty-two orbits drove some of the X-15B's sizing parameters. Bottled oxygen for two days in orbit imposed considerable weight penalties, making necessary a regenerative oxygen system for which no room existed in the X-15A. (51)
After understanding the first flight and making any changes, the second flight would push the altitude envelope. This flight profile evolution was a normal flight test approach. The second orbital flight would start from the same parameters as the initial flight, but then boost to 1,584,000 feet apogee (300 statute miles), with a 500,000 foot perigee. The third flight test would begin from these same elliptical orbital parameters and demonstrate aerodynamic braking and rendezvous techniques. (52) The fourth and final test flight would push the maximum altitude to 3,168,000 feet (600 statute miles) to intensify the re-entry test. In addition to tests of magnetic and gravitational fields, meteorite and radiation measurement and mass spectrometry, the flight profile included re-entry characteristics and guidance tests.
Altitude increases came at the expense of payload weight, because total weight remained about the same. Converting all the payload weight to fuel could have resulted in a 1,900 statute mile apogee. (53)
Orbital construction might also justify the X-15B. Operational human presence required space stations. Space station size outstripped the largest launch vehicles, requiring orbital construction. Conserving robotic spacecraft weight by reducing redundancy could save money. Therefore, it was "important that the concept of manual maintenance in space be investigated early in the space research program." (54)
Design Details (55)
The final detailed design work assumed the SATURN S-1 launch vehicle. The S-1 had 1,500,000 pounds of thrust, and necessitated a modified TITAN second stage with a single XLR-87 engine. Alternative second stages were the SATURN S-II or S-IV (for additional thrust of 80,000 or 800,000 pounds, respectively). (56) The X-15B retained its XLR-99 rocket from the flight research program, but added eight Rocketdyne XLR-101 rockets in the aft fuselage for retrograde thrust at the end of the mission.
A large dorsal payload bay approximately amidships had two sets of power-driven doors, accommodating a wide range of sensors and equipment. The compartment could be segmented for additional fuel tanks. The X-15B would not deploy satellites but operate installed sensors and equipment for the mission and return these, providing a versatile and reconfigurable operational vehicle. (57)
Surprisingly little information exists on the X-15B's anticipated size. Contradictory existing data at times indicates it was the same as the X-15A, or a much larger vehicle. An oxygen regeneration system, second crewmember and the long payload bay indicate that the X-15B would have been similar in planform, but necessarily scaled up from the X-15A.
The structures of the X-15A and X-15B are the most revealing part of the studies, indicating that the X-15B had to be radically different. Reentry heat loads were a major problem with significant unknowns. The best available data on the upper atmosphere, above the highest altitudes of balloon measurements, came from EXPLORER 1, which led to conservatism in estimating the potential heat loads--meaning the requirements encompassed the worst potential case. By the end of 1959, the worst-case heat loads were the ones that drove the skin and internal structure of the X-15B.
The X-15A's 1,200[degrees]F nose temperature and the wing leading edges 1,250[degrees]F allowed its skin to be Inconel X, a high strength nickel-chromium-iron alloy. In reality, the highest heat load on the X-15A was 1,250[degrees]F (although the X-15A-2 was later thought to be capable of 2,400[degrees]F at Mach 8 ). However, the X-15B's heat loads were nearly triple that of the hypersonic research aircraft, reaching 3,400[degrees]F on the nose and 4,900[degrees]F on portions of the leading edges. The X-15B's leading edge structural materials ranged from thorium oxide near the wing roots to beryllium oxide from mid-span to wingtip. Materials for the wing leading edge protective coatings ranged from columbium (good up to 2,800[degrees]F), molybdenum (3,000[degrees]F), graphite (3,800[degrees]F) and finally, tungsten (4,750[degrees]F). The trailing edges might have been Rene' 41. (58)
The internal structure of the fuselage also had to deal with high heat loads, and the X-15A's tubular steel and titanium structures were not up to the re-entry challenge. The X-15B needed a coated molybdenum structural box. (59)
Getting the X-15B to orbit proved harder than expected. After 26 months of design, from December 1959 to February 1962, fabrication would be paced by the availability of the first flight-rated engine in October 1962 (the 34th month of the development). With first vehicle delivery in January 1963, glide tests would have followed 4 months later. The second vehicle would extend speed and altitude by adding two droppable external fuel tanks. Finally, the first launch vehicle boosted flight using a dummy second stage would have been in March 1964, with orbital flights in June 1964 and every 2 months thereafter.
This schedule killed any expectation that the X-15A was a short step away from orbital flight. Also, as for its being a potential competitor to the DYNA-SOAR, the technology problems proved nearly identical, driving the long development schedule. Importantly, in 1959, DYNA-SOAR 1's scheduled first suborbital flight in July 1962 was nearly two years ahead of the X-15B's June 1964 schedule (both of which would in reality have been after John Glenn first American orbital flight in a MERCURY capsule). Hindsight shows both schedules were unachievable, although the X-15B had a smattering of greater realism because of the X-15A's on-going and highly successful flight research program.
While the nation's civil space program, by that time, was focussing on going to the Moon, the military space program had demonstrated the extensive capabilities of robotic spacecraft. As the last glimmer of interest in the X-15B waned in late 1959, the X-15B had not justified its continued support as a way to achieve early human spaceflight, or as a technology testbed for more advanced systems, or as a competitor for the first operational human spaceflight capability.
Final Thoughts
Of course, the X-15B never went beyond design studies. At the same time, it was very much a part of the swirl of evolving spaceplane concepts in the 1950s, and very much a part of the rush to put the first human into space. It was an interesting excursion into the "what ifs" of aerospace history.
More than any other program, it demonstrated the difficulties of extrapolating a research aircraft into a spaceplane. The studies disproved that the technological maturity of the X-15 could easily bootstrap an operational orbital spaceplane program. The X-15B studies identified the same technology problems facing the much more advanced DYNA-SOAR X-20, eliminating its further consideration as a means to mature technologies for the latter program. Its demise can now be said to be understandable.
Yet, in the X-15B, we see things that were both logical and yet to come. The external fuel tanks eventually flew aboard an X-15A for the same purpose as proposed in the X-15B. The dorsal payload bay flexibly containing sensors, experiments or additional fuel later made eminent sense as part of the Space Shuttle.
The studies straddled the transition of robotic spacecraft from crude demonstrations to the first operational capabilities without human presence. Robotic capabilities advanced faster than expected by those whose experience consisted of robotic aircraft programs. The rush to put humans in space for national defense or security reasons died a slow and lingering death, as enthusiasm largely dampened out based on robotic spacecraft success, combined with the high cost technically challenging aspects of human spaceflight.
As an epilogue, a little over two years after the X-15B studies, having pushed DYNA-SOAR beyond achievability, Defense Secretary Robert S. McNamara said, given "the absence of a clearly defined military manned space mission, present military efforts should be directed to the establishment of the necessary technology base and experience upon which to expand, with the shortest possible time lag, in the event firm military manned space missions and requirements are established in the future." (60) Against the earlier perception of the need for human presence to achieve true operational capabilities, robotic spacecraft progressed so rapidly that, by June 1, 1962, Director of Defense Research and Engineering Dr. Harold Brown told Congress he could not define a requirement for military manned space systems. "I think there may, in the end, turn out not to be any." (61)
The military human spaceflight tide had changed. No shortcuts to operational human spaceflight existed, then or now. But, instead of the path not taken, what might the U.S. space programs have been like, had the X-15B and space-planes been pursued?
NOTES
(1.) The most authoritative source on the X-15 program devotes parts of two pages and occasional snippets to the project, by far the most extensive discussion before this paper (Jenkins, Dennis R., Tony R. Landis, Hypersonic--The Story of the North American X-15 (North Branch, Minn: Specialty Press, 2003) pp. 209-210). The other authoritative source on hypersonic research programs was Richard P. Hallion's comprehensive two-volume work (Hallion, Richard P., The Hypersonic Revolution (Wright-Patterson Air Force Base, Ohio: Special Staff Office, 1987) Vol. I, p. I-x), whose scant references to the X-15B suggested that concept was successively shelved and revived for years, finally yielding to the MERCURY capsule. None of the sources, however, adequately explains the designation change of the X-15 to the X-15A. This is usually not mentioned, or discussed only as it applies to the heavily redesigned X-15A-2 (with external fuel tanks). It would appear that the redesignation may actually have been tied to the serious pursuit of the orbital X-15, necessitating a "B" to differentiate its significant differences from the X-15 research aircraft, subsequently designated "A." This supposition, however, seems equally unprovable. Readers interested in the X-15 program itself should also refer to sources such as Jay Miller, X-Planes: X-1 to X-45; Milton Thompson, At the Edge of Space; and Robert Godwin, X-15: The NASA Mission Reports.
(2.) Johnson, Clarence L., M. Smith, Kelly: More Than My Share Of It All (Washington, D.C: Smithsonian Institution Press, 1985); Rich, Ben R. and Leo Janos, Skunk Works -A Personal Memoir of My Years at Lockheed (New York: Little, Brown and Company, 1994), pp. 169-174. Johnson was seemingly aware of and more concerned with how to meet the Air Force's General Operating Requirement 12, the Special Reconnaissance System, discussed below, released within a few months of this meeting.
(3.) Jenkins and Landis 2003, p. 19.
(4.) Ibid; Crowley, Gus. "Minutes of the Meeting, NACA Committee on Aerodynamics," October 4-5, 1954 (Washington, D.C: Files of the NASA History Office).
(5.) Murray, Arthur, Man's Role in Dyna-Soar Flight (Seattle, Wash: The Boeing Company, August 1962, declassified 1965), D2-80726; Temple, L. Parker III, Shades of Gray, National Security and the Evolution of the National Reconnaissance Office (Reston, Va: American Institute of Aeronautics and Astronautics, 2005), pp. 135-137. The latter contains a more complete list, explanation and critique of the list.
(6.) Aviation Week, Mar 10, 1958, p. 39.
(7.) Hansen, James R., Engineer in Charge (Washington, DC: National Aeronautics and Space Administration, 1986), NASA SP-4305, p. 356; Becker, John V., "The Development of Winged Re-entry Vehicles, 1952-1963," unpublished, May 23, 1983, copy in NASA Langley Research Center Historical Archive. Dornberger even pushed to have Bell Aircraft hire Sanger, but this never worked out.
(8.) York, Herbert F., Arms and the Physicist: An Eyewitness Report on a Half Century of Nuclear-Age Drama (New York: Springer-Verlag, 1994), Vol. 12, p. 129-130. Former Director, Defense Research and Engineering, Dr. Herbert York says Dornberger proudly recalled the number to show how indecisive the US government was. To York, however, it only proved how persistent Dornberger was.
(9.) Hall, R. Cargill, C.D. Laurie, eds. Early Cold War Overflights--1950-1956, Symposium Proceedings (Washington, D.C: National Reconnaissance Office, 2003), passim.
(10.) U.S. Congress, House, Committee on Government Operations, Organization and Management of Missile Programs, 86th Congress, 1st Session, Sep 2, 1959, House Report 1121, p. 127.
(11.) Becker 1983, 20; Hansen 1986, pp. 367-368.
(12.) Aviation Week Feb 3, 1958, p. 26.
(13.) Becker 1983, p. 15.
(14.) Temple 2005, p. 134.
(15.) Bowen, Lee, The Threshold of Space: The Air Force in the National Space Program, 1949-1959 (Washington, D.C: USAF Historical Division Liaison Office, 1960), p. 23; Hallion 1987, Vol. 2, pp. 1989. This idea that technology needs could be met in another program not directly related would come back in the more advanced DYNA-SOAR. The designation X-15A is used in this paper to consistently refer to the hypersonic research aircraft, despite the fact that the designation was not used in the early part of the program.
(16.) Becker 1983, pp. 18-19.
(17.) Hallion 1987, Vol. 2, p. 209; Temple 2005, p. 134.
(18.) Hallion 1987, Ibid. Note the advancement in the schedule from the early three-phased program. After combining the projects, first phase development time reduced by three years.
(19.) Headquarters, Air Research and Development Command, "System Development Directive 464L," December 21, 1957, pp. 2, 8, 11, 32; Headquarters, Air Research and Development Command, Detachment 1, "Preliminary Development Plan, System 464L," November 1958; Butz, J.S. Jr., "Orbital Re-Entry Will Intensify Demands On Structures," Aviation Week & Space Technology, April 21, 1958, pp. 50-51. I chose the December 21 date because it records the formalization of a decision reached in the Air Force on October 10 collapsing the efforts into one program. When General White spoke in mid-December, the decision to create DYNA-SOAR out of the other programs was already publicly released.
(20.) Bowen, Ibid.
(21.) White, General Thomas D., "Leadership--in the Conquest of Space," address to the Air Force Academy, December 14, 1957.
(22.) Gantz, Lt.Col. Kenneth F., ed., The United States Air Force Report on the Ballistic Missile--Its Technology, Logistics and Strategy (New York: Doubleday and Company, Inc., 1958), p. 277.
(23.) Jenkins and Landis 2003, p. 209.
(24.) NAVAHO was a supersonic, rocket boosted, ramjet powered cruise missile under development for the Air Force. Subscale models, designated X-10, flew in the mid-1950s, but the project was cancelled in favor of the ATLAS missile. At the time of the X-15B studies, the NAVAHO was in serious technical trouble, but represented an approach well understood by North American engineers.
(25.) Jenkins and Landis, Ibid.
(26.) Syvertson, Clarence A., "Visit to WADC, Wright-Patterson Air Force Base, Ohio, to attend conference on January 29-31, 1958, concerning research problems associated with a man in a satellite vehicle," Memorandum for Director, February 13, 1958, pp. 8-9, in the Headquarters NASA History Office X-15 files.
(27.) Hallion 1987, Vol. 1, p. 8.
(28.) Hallion 1987, Vol. 2, pp. 204-207.
(29.) Syvertson 1958, p. 1.
(30.) Syvertson 1958, p. 9. Becker's responsibilities had included getting the X-15 program going and later serving as NASA's project manager on DYNA-SOAR. His "lessons learned" version of the WADC meeting is in Hallion 1987, Vol. 1, p. 411. The eleven MISS alternatives to early human spaceflight covered the gamut from spheres to missile re-entry nose cone adaptations, to the "stripped" X-15B and winged re-entry vehicles like DYNA-SOAR. Of note in his summary of the 11 alternatives was the absence of Boeing's DYNA-SOAR boost-glide vehicle, which was already well underway, but whose schedule did not fall within the bounds of attaining early human spaceflight. In its place, the only boost-glide vehicles presented were the Northrop and Bell proposals for DYNA-SOAR.
(31.) I owe the satelloid-boost-glide distinction to Hallion (Hallion 1987, Vol. 1, p. 210), which I expanded to differentiate the ballistic vehicles such as the blunt MERCURY capsule, spheres, and missile re-entry shapes. This distinction of Hallion's is especially important to understand the difference between the final version and expectations of the X-20 and the original DYNA-SOAR 1. Originally designed for one purpose as a boost-glide vehicle, circumstances forced it into regimes it was not well suited to operate as a satelloid, which was a major part of the projects undoing.
(32.) Temple 2005, p. 325; Perry, Robert L., A History of Satellite Reconnaissance, Volume IIB--SAMOS E-5 and E-6 (Washington, D.C: The National Reconnaissance Office, October 1973, declassified September 2002), pp. 424-427; Day, Dwayne A., "A Sheep in Wolf's Clothing," Spaceflight, 44, October 2002, p. 10. SENTRY, the original designation of the Air Force photoreconnaissance program under WS-117L, changed to SAMOS in Aug 1959. For narrative simplicity, SAMOS is used consistently here. Several versions of the SENTRY capsules had removed much of the photoreconnaissance equipment replaced by human spaceflight equipment (and crew). These latter concepts were essentially packaging studies, to see whether a human and associated support could be fit into the space left by removing the camera. In some cases, the capsule itself was extended to include both camera and human, but that defeated the cover story by having an outwardly distinguishable capsule for reconnaissance and one for human spaceflight. The packaging was related to the launch vehicle-driven maximum capsule diameter. The SAMOS E-6 was to use a scaled-up TITAN II re-entry vehicle. To accommodate the large format camera, the E-6 was approximately 12 feet long and 8 foot across at the base, easily large enough for a seated astronaut. The CORONA program expended the camera, returning only the film, allowing (in early models) a much smaller size. Day's article covers the rest of the attempts to mix human spaceflight with various SENTRY/SAMOS capsules, such as in the E-3 and E-5.
(33.) Hallion 1987, Vol. 1, p. lxxwiii.
(34.) As explained in this article, the most common assertion about the X-15B is that it kept getting shelved and revived. This paper shows greater continuity behind the X-15B investigations, though some may find it interesting to note that the up-scaled human spaceflight version of the RVX-2 enjoyed its own shelving and reintroduction in the early 1980s. The concept was briefly alive again in the very early days after the establishment of Air Force Space Command. The author of this article was called upon to review this proposal while assigned to Air Force Systems Command at the time.
(35.) Temple 2005, p. 325; Day, Dwayne A., John M. Logsdon and Brian Latell, eds., Eye in the Sky--The Story of the CORONA Spy Satellites (Washington, D.C: Smithsonian Institution Press, 1998), p. 74.
(36.) Hallion 1987, Vol. 1, p. 411. Heroic human presence as fundamental to real capabilities was popularized in Tom Wolfe's best-selling book, The Right Stuff, minimizing the role of humans in the orbital MERCURY capsules.
(37.) Temple 2005, p. 144; Hallion 1987, Vol. 1, p. 411.
(38.) Swenson, Lloyd S., Jr., James M. Greenwood, and Charles C. Alexander, This New Ocean: A History of Project Mercury, (Washington, D.C: National Aeronautics and Space Administration, 1966), pp. 78-80.
(39.) Temple 2005, p. 144.
(40.) Syvertson 1958, p. 11. Syverston sketched each of the basic shapes and then detailed important aspects of each of the 11 concepts, one being the estimated development time to manned spaceflight.
(41.) Jenkins and Landis 2003, Ibid.
(42.) Gantz 1958, pp. 296-297. In testimony before the Senate Committee on Armed Services' Preparedness Investigating Subcommittee, referring to the "manned satellite," General Schriever said he preferred "not to say anything more about the program that has been under discussion ... because of its classification." When Congressman Weisl clarified the question referred to the X-15, Schriever explained that the X-15 was not a satellite, but a rocket-powered airplane. Senator Barrett responded, "Yes, I understand that, General, but I was thinking about an extension of the X-15, and it would be perfectly agreeable to wait for executive session." Schriever explained its relationship to the hardware then in existence supporting the ballistic missile program. Experimental recovery flights were possible with existing hardware, he claimed. The testimony was on December 17, 1957 and January 8-9, 1958.
(43.) This effort comprising only studies is very difficult to reconstruct. Western Development Division was indeed involved in the evaluation and possibly sponsorship of the X-15/SATURN in 1959, when Jenkins and Hallion indicate it had been shelved. The two Air Force development centers responsible for aircraft and satellites had a lengthy rivalry on the topic of spaceplanes. Each center had its own ways to extend aircraft technology higher and faster to become satellites or to make satellite technology capable of aerodynamic flight. I suspect that, as interest in the X-15B waned at Wright Air Development Center, it was either picked up briefly or worked collaterally at Western Development Division. This is not yet provable. I documented some of this rivalry relating to spaceplanes in Shades of Gray.
(44.) Jenkins and Landis 2003, Ibid.
(45.) North American Aviation Report, SATURN/X-15 Flight Research Program Report, November 19, 1959, NA 59-1586, SECRET original declassified by NASA Headquarters, 9 and passim; North American Aviation Report, Technical Summary Report, SATURN/X-15, November 19, 1959, NA 59-1247, SECRET original declassified by NASA Headquarters, passim. These newly declassified reports were obtained through FOIA from NASA Headquarters.
(46.) North American Aviation Report, NA 59-1586, p. 5.
(47.) North American Aviation Report, NA 59-1586, restored from the original by Ms. Betty Temple, as with all drawings in this article.
(48.) Jenkins and Landis 2003, p. 28.
(49.) Hallion 1986, Vol., 1, pp. 209-210.
(50.) Jenkins and Landis 2003, p. 163.
(51.) The X-15 life support system used oxygen stored in canisters, sufficient for short duration atmospheric missions, but not for long duration orbital missions. Adding more oxygen bottles would be costly in terms of weight and performance, as well as operationally limiting. Orbital flight would have required some form of regenerative breathing system. At the time, the rule of thumb that one pound into 100 nautical mile orbit required 100 pounds of fuel and launch vehicle was unknown, but the expense of extra weight was appreciated. The X-15B studies showed a good anticipatory understanding of the kinds of tradeoffs between fuel and payload each profile represented.
(52.) North American Aviation Report, NA 59-1586, p. 6.
(53.) North American Aviation Report, NA 59-1586, p. 29.
(54.) North American Aviation Report, NA 59-1586, p. 12.
(55.) For a more detailed description of the technical details of the X-15B, see Temple, L. Parker III, "X-15B: The Spaceplane That Almost Was," Paper presented at the 57th International Astronautical Congress, Valencia, Spain, October 2006, IAC-06-E4.3.01.
(56.) North American Aviation Report, NA 59-1247, 8.
(57.) The payload bay was narrow and long, apparently displacing one fuel tank from the original X-15 design. Interestingly, surviving cutaway drawings in the technical reports show a dorsal payload bay, but do not remove the internal fuel tank, which is contradictory.
(58.) North American Aviation Report, NA 59-1247, pp. 95, 102; North American Aviation Report, NA 59-1586, p. 96. Interestingly, at the same time columbium was considered the material for the X-20 DYNA-SOAR, but the amount required exceeded the world's annual production of the element. Had both continued, there would have been competition for resources to complicate their acquisition.
(59.) Jenkins and Landis 2003, pp. 179, 181; Hallion 1986, Vol. 1, pp. 35-37; North American Aviation Report, NA 59-1247, pp. 95, 102.
(60.) Carter, Launor F., Interpretive Study of the Formulation of the Air Force Space Program (Washington, D.C: US Air Force History Office, February 4, 1963), pp. 3, 16.
(61.) U.S. Congress, House, Committee on Government Operations, 85th Congress, 2nd Session, June 4, 1965, House Report 445, p. 82; U.S. Congress, Senate, Committee on Aeronautical and Space Sciences, NASA Authorization for fiscal year 1963, 87th Congress, 2nd Session, June 1962, p. 348. This was hardly the end of the push for military human spaceflight, but the subsequent absence of such programs speaks volumes about the realities. Conceptual studies replaced the efforts aimed at actually developing flying systems, as both Air Force Systems Command's Aeronautical Systems Division and its Space and Missile Systems organization/Space Systems Division pursued concepts variously named Aerospaceplane, Trans-Atmospheric Vehicles, Reusable Aerodynamic Space Vehicles, and other names. These are covered in more detail in Temple, 2005, passim Improved rocket technology and other advances brought space-planes back into vogue in the late 1980s with the National Aerospace Plane (NASP). However, neither the NASP nor any of its predecessors were ever considered to be the key to operational uses of space--robotic spacecraft remain unchallenged for their operational utility to this day.
Dr. L. Parker Temple works on space programs as a systems engineer, but also has a second career as an historian. He was a career Air Force officer, combining a career of flying, promulgating space policy and space systems acquisition. Recently, he was honored by his election as a Fellow of the American Institute of Aeronautics and Astronautics, and was the author of AIAA's best selling book, Shades of Gray, National Security and the Evolution of the National Reconnaissance Office.
He currently lives in Virginia.
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