Rapid Response: Part Six: The WS-110A, The North American Aviation XB-70 and RS-70 Valkyrie

"It's not a plane, it's a three plane formation!"--General Curtis LeMay, CINCSAC








From youtube:




From youtube:




From unrealaircraft.com:

Lost Classics - North American XB-70 Valkyrie




In 1954, the formidable commander of the USAF's Strategic Air Command, Gen. Curtis E. LeMay, began to look for a new strategic bomber. In his view the B-52 (which is still in service today) and the more exotic Mach 2 Convair B-58 had limited capability.



By 1955 SAC had three huge programs under way. One was Weapon System 107A, which was development of an ICBM (intercontinental ballistic missile). Another was WS-110A for a CPB (chemically propelled bomber) of international range and supersonic speed; and WS-125A was for an NPB (nuclear propelled bomber) which could fly continuously without landing to refuel. Six companies bid for the CPB, and on 11th November, 1955, both Boeing and North American received Phase I design contracts.



North American started with evident determination to overcome the drag of supersonic flight. They worked on a canard design, with outer wing and fuel pod units which could be detached, allowing the bomber to land at a little over a quarter of its takeoff weight. In this first design the bomber was basically built in three parts, a central pod that contained the engines, crew, some fuel and the bombs, and two very large side units on the left and right that were most of the wing and tail area, as well as containing large fuel tanks. The result looked something like a very large P-38 Lightning, with the central pod being much longer and including canards.



Normally the plane would "stay together" in one very large piece. It was over a million pounds on launch, larger than a 747-400. On a combat mission the plane would fly in this combination to enemy airspace at subsonic speeds. By the time it arrived the fuel tanks in the outer portions of the wings would be empty, and at that point the plane would "break". The outer wings and tail would fall off, leaving the inner pod and the stubs of the wings. With very little of the plane left, it would now have a huge power-to-weight ratio, so it would accelerate to Mach 3 for a "dash" to it's target.



Curtis LeMay was not enthusiastic about the design, and is credited with the response, "Hell, this isn't an airplane, it's a three-ship formation." North American, as one contender for the WS-110 contract, had meanwhile been doing their homework. They calculated that the amount of fuel needed to cruise at Mach 3 all the way to target turned out to be less than that needed to fly the same distance at high subsonic speed. It would need more fuel flow, but the aircraft would cover the ground faster.



Three times the speed would not require three times the fuel flow, but a good deal less. This is a result of something called "wave drag", which means, simply, that it's actually hardest to fly right under the speed of sound. As a result, if they could produce a plane that could handle the heat, and has enough thrust to get through that wave drag, they could fly faster without impossible fuel demands. They proposed steel a construction because it could take the heat of high speed flight, and it was cheap, a real concern if they were going to build hundreds of them.



Their design was eventually accepted, with the long, graceful fuselage lines, high canard and delta wing, with tilting wing tips which served to trap compression under the wing, providing additional lift. In wind tunnel tests it looked as if, with newly developed high-performance aircraft fuels, compression lift would assist the WS-110A aircraft to a cruise of Mach 3, a sustained speed which not long before had been out of reach.



Use of ethyl borane fuel stood to further enhance the bomber's performance, and RAF Flying Review of September 1958 dubbed WS-110 the "Boron Bomber". They guesstimated from "unofficial reports" that it would fly at 100,000 feet, cruise at Mach 2 with room for Mach 3 "dash" performance, and achieve a 6,000 mile range without refuelling.



In 1958 the project came together, and the aircraft had a name, the B-70. After passing through five separate company design numbers with North American, the B-70 would go ahead as their design NA-278. It would be plagued by a series of structural problems largely related to its ground-breaking technology, and very soon changing government views would threaten the future of the project.



About 70% of the Valkyrie was to be of a new stainless steel. The interior structure was mostly corrugated sheets, and the skin was a brazed honeycomb sandwich of very thin steel, yet very strong. The parts most subjected to heat were of a material never before used in an aircraft, René 41. Aerofoil surface edges were machined to extreme sharpness.



The six GE engines were housed in an engine box under the wings, profiled to generate compression lift. On "zip fuel" one engine alone made more noise than any air-breathing engine in history. Development of the two prototypes was to cost around $1,500M, making them the most expensive two aircraft built to that date, and worth, according to one estimate, about ten times their weight in gold.



In mid-1959, the B-70's future came into question, with enormous expenditure going into missile systems. Manned aircraft were considered in some quarters to be near-obsolete. To make matters more awkward, the expensive boron fuel program was cancelled.



Then, in December 1959, the B-70 project itself was cancelled, except for completion of a single prototype. The planned first flight was rescheduled from January to December, 1962. It was still hoped that by 1966 an SAC wing might use B-70s if the pro-missile lobby could be persuaded to change their views.



After a review in 1960, the program was partially restored, and allowance was made for up to twelve fully-operational B-70s to be built, in addition to the prototype. In March 1961, during the Kennedy administration, it was still held that missile development made the B-70 unjustifiable. It was reduced to the status of a Mach 3 research project, with an airframe potentially useful as a bomber. Secretary of Defense Robert McNamara promptly cut back the program to three prototypes, which were ordered on 4th October, 1961; but the third was cancelled a few weeks later, leaving only aircraft with the USAF numbers 62-001 and 62-207.



The USAF tried to keep some promise in the project by changing the role of the B-70 to strike-reconnaissance late in 1962, and temporarily redesignated the aircraft RS-70. They proposed an initial delivery of sixty RS-70s to enter service in 1969 and a further 150 the year after. Apart from a slight flicker of interest from the House Armed Services Commission, it was wishful thinking on the USAF's part, the more so when the existence of the purpose-built Lockheed A-12, which had also been under development since the late 1950s, was revealed to President Johnson late in 1963 and announced to the world in February 1964.



The first XB-70 was nearly complete in late 1962 when electrolytic corrosion between the various grades of steel used in its structure was discovered. Extensive inspection and rebuilding took up a further two years. In 1963 funding dried up, and the XB-70 project was left to starve, existing only as a research project. The first flight was pushed ahead to late 1963 for the first prototype, and mid-1964 for the second.



Assembly of the first XB-70A was completed in mid-1963, but solution of a fuel leak problem took another eighteen months. Finally, on May 11, 1964, the XB-70A emerged from its hangar at Palmdale, California. Earlier releases of information had not fully prepared its audience for its size, its sleek lines, and its poised menace.



The canard design enabled the foreplane to be used to assist with trimming the aircraft across a wide speed range from a minimum 150 kts. (278 km/h) landing speed, up to Mach 3; they could also serve as flaps. The compression lift derived from the shock wave at the front of the intakes was a retained benefit, and apart from boosting lift by as much as 30%, also reduced drag by allowing shallower angles of attack. The tilting wing tips were kept level on takeoff, and tilted down to 25° at low speeds and altitudes. They served to minimise trim changes in pitch. At high speeds and altitudes, they would be dropped further, to 65°, enhancing compression lift.



A variable-geometry system was fitted to the nose, allowing a ramp forward of the cockpit to be raised for supersonic flight or lowered for a direct forward view. This visor was merely aerodynamic. The cockpit was sealed behind a vertical pressure-bearing flat screen.



Inside their compartment, the four crew members were provided with airliner comfort and could work in their shirt-sleeves. They sat in cocoon-like seats with clamshell doors which, in the case of pressurisation loss, would provide them with individual sealed escape capsules. The capsules contained their own oxygen bottles and emergency supplies, and basic controls to close the throttles and trim for an emergency descent, whilst monitoring the instruments through a window in the capsule. The capsules could be re-opened at a safe altitude, or rocket-ejected through jettisonable roof panels.



A single bay between the engine ducts and engines could carry groups of any nuclear bombs used by SAC. The bay had doors which slid open automatically at the last moment before weapon release. Although not part of the requirment, studies were also made into various external ballistic weapon loads.



On its first flight on 21st September, 1964, the XB-70 was flown by Colonel Joe Cotton and North American's chief test pilot Alvin S. ('Al') White. The aircraft failed to achieve Mach 1 due to an inability to retract the main undercarriage. Number 2 engine suffered foreign object damage; and another fault locked the two left rear main tyres, which blew on touchdown. In general, flight development was encouraging and proceeded much as predicted.



Both prototypes reached Mach 3 for the first time on their 17th flights, respectively on October 15th, 1965 and January 3, 1966. The XB-70A was flown for the first time using the crew capsule controls on December 20, 1965.



On 8th June, 1966, aircraft 62-207 was to complete various tasks then pose, with a small group of other General Electric-engined aircraft, for some publicity shots for GE. Al White was to be pilot. As the work load was light, Maj. Carl S. Cross was allowed on board for his first ride as co-pilot. Accompanying the XB-70 were a McDonnell F-4 Phantom of the US Navy; a Northrop F-5 and a Northrop T-38 (both North American crewed); and an F-104 Starfighter flown by NASA pilot Joe Walker, who had flown the X-15.



The formation was controlled by a GE-engined Learjet, with no radio frequencies in common with the XB-70. Radio messages had to be relayed via Edwards AFB. GE got a number of good photos by 9.30 am. and ended the photo session about 9.35. Apparently against the dictates of common sense, the NASA F-104 was edging up close to the XB-70, finally moving in below the right wingtip.



The 30° crank-down of the Valkyrie's wingtips generated a strong vortex, and this whipped the F-104 upside-down and across the top of the larger aircraft's wings. It took away almost all of the XB-70's tail fins. The F-104 fell back in a ball of fire; the Learjet resumed picture-taking.



For some seconds the Valkyrie flew steadily, then began a slow roll, turning into a violent yawing. Descending flat-on to the airflow, a large part of the left wing broke away. Soon after, White ejected in his crew capsule. The XB-70 stopped oscillating and fell, slowly rotating, hitting the ground almost flat about four miles north of Barstow. Why Maj. Cross, with 8,528 flying hours, failed to eject is unknown, and he died in the crash.



Perhaps unfairly, GE suffered a great deal of ill-will for the incident, although they had done nothing wrong, and for some time it was impossible to arrange PR exercises and aerial photography.



The surviving XB-70, 62-001, continued to amass research data, largely for NASA. Its last flight was on 4th February, 1969, to the USAF Museum, Wright-Patterson, where it remains, alongside the Convair B-36, the largest aircraft on display.



Particular thanks to Maury Markowitz for his substantial input on the XB-70.

 
 
From rp-one.net:
 
 

 
The Model 725-87 cruises under a full moon.










Introduction





In 1955 the US Air Force issued System Requirement No. 22 for Weapon System (WS) 110A, a chemically powered bomber to succeed the B-52 in SAC service from 1963. This aircraft was to be able to deliver thermonuclear weapons to targets within the Soviet Union from bases in the continental US. The weapons were to be free-fall bombs or a 300+ nautical mile range cruise missile. The bomber itself was to have an un-refuelled radius of more than 4000 nautical miles, with a subsonic cruise and high supersonic dash over the target.



Both Boeing and North American Aviation studied various designs to meet this requirement. The winning North American proposal was ultimately developed into the XB-70 Valkyrie, which flew in prototype form in 1964. The Boeing configurations ranged from 16-engined developments of the B-52 to trapezoidal and delta winged machines.



A more radical concept developed by Boeing but used by both competitors was the "floating panel". In this arrangement, the outer wings of the aircraft, with their own fuel pods, undercarriage and even engines, acted as sub-craft and were free to rotate in flight to eliminate loads on the central airframe. After the subsonic cruise section of the flight, these outer panels would be jettisoned and the bomber would accelerate to supersonic speeds for the attack. Although the use of large jettisonable pods had been demonstrated on the Convair B-58 Hustler, the idea was not carried forward and the final designs presented by North American and Boeing were monolithic bombers.





Outline





This page presents impressions and brief summaries of some of the Boeing designs. The in-page images are reduced resolution files. Clicking on the images will open higher resolution images, typically 1024 by 768 pixels and 400kb.

















The Model 725-87 composite bomber design, featuring floating panels with fuel pods, engines and landing gear.






















Overall length of the Model 725-87 was 165 feet and overall wingspan was 131 feet.







© Richard Pawling, 2007

Correspondence to richard@rp-one.net

 
 
The WS-110A
From Wikipedia:

WS-110A






From Wikipedia, the free encyclopedia




WS-110A ("Weapon System 110A") was a project by the United States Air Force in the 1950s to develop a supersonic bomber aircraft capable of delivering nuclear weapons. Proposals for such an aircraft were submitted by Boeing and North American Aviation. Although the program was put on indefinite hold before any actual designs were completed, it paved the way for the B-70 program.

History



Background



Boeing Aircraft Corporation's MX-2145 Project with Rand Corporation that started in January 1954 explored what sort of aircraft would be needed to deliver the various nuclear weapons then under development. Providing for a long range and high payload were obvious requirements, but they also concluded that after bomb-release the plane would need supersonic speed to escape the weapon's critical blast-radius. Jet engines of the time had poor fuel efficiency.[citation needed] An aircraft capable of carrying a reasonable bomb load to the Soviet Union from the continental United States had to carry a large fuel load (and thus be very large itself) due to the unrefueled range required.[1][2]



The aviation industry had been examining this problem for some time. There was considerable interest in the use of nuclear powered aircraft in the bomber role from the mid-1940s.[3][N 1] Nuclear engines in aircraft used the heat generated by a nuclear reactor in place of jet fuel, giving it virtually unlimited cruising range.[4] In addition to solving the range issue, these aircraft could be flown to holding areas away from the airbases and kept in the air for extended periods of time, making them immune to sneak attack. Accordingly, Boeing developed plans for a nuclear powered bomber equipped with afterburners that used chemical fuel. Lockheed and Convair proposed similar designs.[citation needed]



Another possibility was the use of boron-enriched "zip fuels", which improved the energy density of the fuel by about 40%.[5] Various U.S. government agencies had been experimenting with zip fuels for some time, and they believed that once the problems were solved, zip fuel would become almost universal for high-speed aircraft. Although the advantages of a zip-fueled aircraft would not be as great as those of a nuclear powered one, it would offer a real performance increase and was a relatively straightforward development of existing engines and fuels.[5]



Air Force studies



In October 1954, the Air Force issued General Operational Requirement No. 38, which was quite general and called simply for an intercontinental manned bomber which would replace the B-52 beginning in 1965. March 1955's GOR.81 was more specific, calling for a nuclear-powered bomber with a combat radius of 11,000 nautical miles (20,000 km), capable of flying up to 1,000 miles (1,600 km) at a speed greater than Mach 2 at altitudes greater than 60,000 feet (18,000 m) with a 20,000 lb (9,100 kg) payload, revising this to 25,000 lb (11,000 kg) in GOR.82 later that month.[6][7]



The Air Research and Development Command (ARDC) decided to separate the two approaches, and issued a requirement for "Weapon System 110A", which asked for a Mach 0.9 cruising speed and "maximum possible" speed during a 1,000-mile (1,600 km) entrance and exit from the target. The target date for the first operational wing of these bombers was July 1964, reduced a year in comparison to earlier GOR's. The nuclear approach became "Weapon System 125A", while the ICBM work was organized under "Weapon System 107A".[8]











NAA's original proposal for WS-110A. The "floating panels" are large fuel tanks containing conventional JP-4 fuel used during the long subsonic cruise, each is the size of a B-47. Once ejected, the engines would burn "HEF", or zip fuel, during the high-speed dash phase.

In early 1955, the Air Force issued GOR.96, which called for an intercontinental reconnaissance system with the same general requirements as WS-110A, called WS-110L.[9] The two requirements were combined soon afterwards, becoming Weapon System 110A/L. The nuclear-powered version was dropped during this period, given the problems in that program's development, as well as a general feeling of optimism about the zip fuels. In June 1955 the Air Staff directed that the details of WS-110A/L be released to the aviation industry and that a request for proposals be issued. Although six contractors were given the requirements, only Boeing and North American Aviation (NAA) submitted proposals. On 8 November 1955, the Air Force issued letter contracts to both Boeing and North American for Phase 1 development. The contracts called for models, design reports, wind tunnel tests, plus a mock-up.[9]



In 1956, initial designs were presented by the two companies. Although zip fuels improved range, the overall effect was not very large, perhaps 10%, so both designs featured huge wingtip fuel tanks that could be jettisoned before a supersonic run on the target. In the case of the North American design, the entire outer portion of the wings was jettisoned as well, resulting in an aircraft that looked somewhat like a very large F-104 Starfighter after being "broken up".



The Air Force evaluated their designs and in September 1956 deemed them too large and complicated; the huge fuel load resulted in takeoff weights of 700,000 pounds, making safe operation from existing runways extremely difficult. They were also far too large to fit in existing hangars. Curtis LeMay was not enthusiastic about the design, claiming "Hell, this isn't an airplane, it's a three-ship formation."[8] NAA and Boeing's study contracts were extended to further develop their bomber designs.[7] The next month the program was put "on hold", although the companies were told to continue any low-level development they could.



References



1.^ York 1978, p. 70.

2.^ "B-70 Valkyrie". Globalsecurity.org. Retrieved 24 May 2011.

3.^ a b von Kármán, Theodore. "Where We Stand: First Report to General of the Army H. H. Arnold on Long Range Research Problems of the Air Forces with a Review of German Plans and Developments". Atomic Energy for Jet Propulsion. Washington, D.C.: Government Printing Office, 22 August 1945.

4.^ Bikowicz, Brian D.. "Atomic Powered Aircraft – Politics". Atomicengines.com. Retrieved May 24, 2011.

5.^ a b Schubert, Dave. "From Missiles to Medicine: The development of boron hydrides". Pioneer Magazine. March 2001.

6.^ North American XB-70A Valkyrie, J Baugher.

7.^ a b Jenkins 1999, Ch. 1

8.^ a b Lost Classics - North American XB-70 Valkyrie

9.^ a b Pace 1986, p. 14.



Notes



1.^ Quote by Theodore von Kármán (1945): "The size and performance of the craft driven by atomic power would depend mainly on ... reducing the engine weight to the limiting value which makes flight at a certain speed possible."[3]


Bibliography

Jenkins, Dennis R. and Candis, Tony R. Valkyrie: North American's Mach 3 Superbomber Specialty Press, 2004. ISBN 1-58007-072-8

Jenkins, Dennis R. B-1 Lancer, The Most Complicated Warplane Ever Developed. New York: McGraw-Hill, 1999. ISBN 0-07-134694-5.

Pace, Steve. "Triplesonic Twosome." Wings, Volume 18, No. 1, February 1988.

 
 
From vectorsite.net:
 
The North American XB-70 Valkyrie


v1.2.5 / 01 oct 10 / greg goebel / public domain



* After World War II, the US Air Force's (USAF) strategic bombers grew ever more capable, each reaching higher altitudes and greater speeds than its predecessor. By the late 1950s, the USAF was planning to develop a "super-bomber", the North American "B-70", that would be built in large numbers. In reality, improvements in Soviet air defenses and the development of the ICBM made the B-70 obsolete before it ever flew. The B-52, which was planned to have been an interim type leading to the B-70, still remains in first-line service in the 21st century. However, two XB-70s were completed as supersonic test aircraft, and were among the sleekest and most impressive aircraft that ever flew. This document provides a history and description of the XB-70.



[1] ORIGINS


* The XB-70 began life in 1954, in design studies performed for a USAF request that formally emerged in 1955 as "Weapons System 110 (WS-110)", which specified a high-altitude bomber that would carry a heavy warload and cruise at Mach 3 over long range at high altitude.



Boeing and North American submitted proposals, but the concepts weren't exactly what the Air Force wanted. These aircraft would have had a loaded weight of over 450 tonnes (a million pounds); were too big to fit into existing B-52 hangars and other facilities; and could only achieve Mach 3 for a short dash over the target. The proposals were rejected. Both companies went back to the drawing board, and found that they could in fact build a bomber with a warload of 18.2 tonnes (20,000 pounds) that could cruise at Mach 3 at an altitude of over 21 kilometers (70,000 feet), and would be able to use existing facilities.



North American won the competition in December 1957. The company's design, designated "B-70", was of canard configuration, featuring a long, sleek fuselage with small canard wings mounted near the cockpit, and a large delta wing in the rear that was fitted with twin tailfins. The bomber was to be powered by six General Electric J93 turbojets, each with an afterburning thrust of over 127.5 kN (13,000 kgp / 30,000 lbf). The engines, bomb bay, and landing gear were all contained in a single wedge-shaped unit under the center of the delta wing. The tricycle landing gear featured twin-wheel nose gear and four-wheel main gear assemblies. The aircraft was to be constructed mostly of lightweight stainless-steel honeycomb, with titanium used in certain heat-critical sections.



The B-70 also incorporated an unusual feature: the outboard 6 meters (20 feet) of the wings could fold down. This scheme was derived from research that showed that trapping the shockwave generated from the nose of a supersonic aircraft wing could generate very high lift. The B-70 would take off with the wingtips straight; at subsonic cruise speed, they would be lowered to 25 degrees, and above about Mach 1.4, to 65 degrees. The folding wingtips not only improved lift, they also allowed smaller tailfins to be used, and compensated for the delta wing's backwards shift in its center of lift as speed increased.




* However, as the B-70 design solidified, the Air Force began to have second thoughts. Intercontinental ballistic missiles (ICBMs) were clearly the way of the future for strategic nuclear strike, and the B-70 began to seem like an expensive luxury. In December 1959, the entire program was cut back to a single prototype. This wasn't the last word on the matter, though, since big weapons procurement efforts acquire a momentum of their own, and by mid-1960 funding for the B-70 program had been restored to a level adequate for as many as a dozen of the bombers.



The logic working against the concept still held true, and had been emphasized on 1 May 1960, when an American Lockheed U-2 spy plane was shot down over the Soviet Union by an SA-2 surface-to-air missile (SAM). Not only was the B-70 redundant in the face of the emerging US ICBM force, but improved SAM defenses meant that its high speed, high altitude flight did not offer much protection against being blown out of the sky. On 1 March 1961, US President John F. Kennedy announced that the B-70 program was to be scaled back once more. Three aircraft would be completed, including two "XB-70" flight test prototypes and one "YB-70" operational prototype.



The two XB-70s were to be flight research aircraft only. Most of the combat-related avionics, such as the bombing-navigation system, were deleted, and the bombardier and navigator positions were deleted as well, leaving provisions only for pilot and copilot. The US National Aeronautics & Space Administration (NASA) would collaborate with the USAF on the flight tests. The YB-70 was to have full combat systems. The idea was that the machine would be useful as a hedge against changing conditions to retain the option of putting the B-70 into production after all. However, the expense and the continuously dwindling logic of fielding the B-70 meant that only the two prototypes were built.


[2] XB-70 IN FLIGHT

* The first XB-70 was rolled out at North American's Palmdale, California, facility on 11 May 1964. By this time the type had been named the "Valkyrie", and the initial prototype was designated "Air Vehicle 1 (AV/1)", with tail number 20001. AV/1 performed its first flight on 21 September 1964. After a number of teething problems, AV/1 punched through Mach 1 for the first time on 12 October 1964.





Flight tests of AV/1 continued into 1965, with the aircraft demonstrating sustained supersonic flight at speeds of Mach 1.4 to above Mach 2. On its 12th flight, on 7 May 1965, while cruising at Mach 2.58, a piece of the wing broke away and shut down four of the engines. The aircraft managed to make it back to the runway, but all six engines had to be replaced.




NORTH AMERICAN XB-70 VALKYRIE:

_____________________ _________________ _______________________



spec metric english

_____________________ _________________ _______________________



wingspan 32 meters 105 feet

wing area 586.2 sq_meters 6,298 sq_feet

length (no test boom) 56.7 meters 185 feet 10 inches

height 9.38 meters 30 feet 9 inches



empty weight 136,055 kilograms 300,000 pounds

max takeoff weight 246,365 kilograms 542,000 pounds



maximum speed 3,310 KPH 2,056 MPH / 1,787 KT

service ceiling 23,580 meters 77,350 feet

ferry range 6,925 kilometers 4,300 MI / 3,740 NMI

_____________________ _________________ _______________________





* By the summer of 1965, AV/2, with tail number 20207, had been rolled out and was ready to fly. There would be no AV/3, since the third XB-70 had been canceled even before the initial flight of AV/1. AV/2 took to the air on 17 July 1965, and began its own series of supersonic flight tests. Tests continued with both XB-70s. On 14 October 1965, AV/1 made a short dash through Mach 3 at 21 kilometers altitude, but lost a small chunk of her outer wing. AV/1 was never flown faster than Mach 2.5 again. There were similar concerns that AV/2 might not be robust enough for Mach 3 flight, either. Flight tests were planned so that the aircraft would be run at Mach 2.8 or Mach 2.9 for an extended time to thermally condition the aircraft for dashes above Mach 3.

Mach 3 flight imposes a severe thermal burden on an aircraft. Heat buildup rises drastically with increases in speed at high Mach, and is far more a limiting factor to high-speed flight than engine power. The XB-70 was an extremely "clean" aircraft, which minimized heat buildup, but the nose and other leading parts of the aircraft did rise to 330 degrees Celsius (625 degrees Fahrenheit), while the rest of the aircraft remained at 232 degrees Celsius (450 degrees Fahrenheit).



Airframe cooling was provided by an ingenious, if somewhat hair-raising, arrangement of the fuel tanks that allowed the fuel to soak up the heat from the airframe. The hot fuel was bled off to the engines, conveniently preheated to improve engine performance. However, as the fuel was bled off, the space evacuated had to be replaced with inert nitrogen gas, since if any appreciable amount of oxygen leaked in, the fuel in the tanks would explode immediately.



In any case, tests continued, with AV/2 pushing the envelope up to and past the Mach 3 mark. It provided data relevant to the supersonic transport (SST) designs then being considered, in particular showing that the sonic booms caused by such an aircraft would be unacceptable over populated areas.





The North American XB-70 and RS-70 Valkyrie
From Wikipedia:

North American XB-70 Valkyrie






From Wikipedia, the free encyclopedia

XB-70 Valkyrie



XB-70 of Dryden Flight Research Center in 1968


Role:  Strategic bomber and Supersonic research aircraft

Manufacturer:  North American Aviation

First flight:  21 September 1964

Retired:  4 February 1969

Status:  Retired

Primary users:  United States Air Force and NASA

Number built:  2

Program cost:  US$1.5 billion[1]

Unit cost:  $750 million (average cost)





The North American Aviation XB-70 Valkyrie was the prototype version of the proposed B-70 nuclear-armed deep-penetration bomber for the United States Air Force's (USAF) Strategic Air Command. Designed by North American Aviation in the late 1950s, the Valkyrie was a large six-engined aircraft able to fly Mach 3+ at an altitude of 70,000 feet (21,000 m), which would have allowed it to avoid interceptors, the only effective anti-bomber weapon at the time.



The introduction of effective high-altitude surface-to-air missiles (SAMs), the program's high development costs, and changes in the technological environment with the introduction of intercontinental ballistic missile (ICBM)s led to the cancellation of the B-70 program in 1961. Although the proposed fleet of operational B-70 bombers was canceled, two prototype aircraft were built as the XB-70A and used in supersonic test flights from 1964 to 1969. One prototype crashed following a midair collision in 1966; the other is on display at the National Museum of the United States Air Force in Ohio.

Development



Background



Main article: WS-110A



Boeing's MX-2145 Project with RAND Corporation that started in January 1954 explored what sort of aircraft would be needed to deliver the various nuclear weapons then under development. Providing for a long range and high payload were obvious requirements, but they also concluded that after bomb-release the plane would need supersonic speed to escape the weapon's critical blast-radius. An aircraft capable of carrying a reasonable bomb load to the Soviet Union from the continental United States had to carry a large fuel load (and thus be very large itself) due to the unrefueled range required.[2][3]



The aviation industry had been examining this problem for some time. There was considerable interest in the use of nuclear powered aircraft in the bomber role from the mid-1940s.[4][5][N 1] Another possibility was the use of boron-enriched "zip fuels", which improved the energy density of the fuel by about 40%.[6] Various U.S. government agencies had been experimenting with zip fuels, and they believed that once the problems were solved, zip fuel would become almost universal for high-speed aircraft. Zip fuel offered a performance increase with development of existing engines.[6]



The U.S. Air Force followed these developments closely, and in October 1954 issued General Operational Requirement No. 38 for a new bomber with the intercontinental range of the B-52 and the Mach 2 top speed of the Convair B-58 Hustler.[7] The new bomber was expected to enter service in 1963.[8][N 2] The nuclear-powered bomber was placed under "Weapon System 125A" and pursued simultaneously with the chemical or zip fuel-powered bomber.[9]



NAA's original proposal for WS-110A. The "floating panels" are large fuel tanks the size of a B-47.[10]

The USAF Air Research and Development Command (ARDC) issued a new requirement for "Weapon System 110A", which asked for a chemical fuel bomber with Mach 0.9 cruising speed and "maximum possible" speed during a 1,000 nautical miles (1,609 km) entrance and exit from the target. The requirement also called for a 50,000 pounds (22,670 kg) payload and a combat radius of 4,000 nautical miles (4,600 mi, 7,400 km).[1] The Air Force formed similar requirements for an WS-110L intercontinental reconnaissance system in 1955, but this was later canceled in 1958 due to better options.[11][12][13] In July 1955 six contractors were selected to bid on WS-110A studies.[9] Boeing and North American Aviation (NAA) submitted proposals, and on 8 November 1955 were awarded contracts for Phase 1 development.[12]



In mid-1956, initial designs were presented by the two companies.[14][15] Zip fuel was to be used in the afterburners to improve range by 10% to 15% over conventional fuel.[16] Both designs featured huge wing tip fuel tanks that could be jettisoned when their fuel was depleted before a supersonic dash to the target. On both Boeing and North American designs, the entire outer portion of the wings was jettisoned with the fuel wing tanks.[14] The two designs had takeoff weights of approximately 750,000 pounds (340,000 kg) with large fuel loads. The Air Force evaluated the designs, and in September 1956 deemed them too large and complicated for operations.[17] The USAF ended Phase 1 development in October 1956 and instructed the two contractors to continue design studies.[15][17][18]



New designs



During the period that the original proposals were being studied, advances in supersonic flight were proceeding rapidly. The "long thin delta" was establishing itself as a preferred planform for supersonic flight, replacing earlier designs like the swept wing and compound sweep as seen on designs like the Lockheed F-104 Starfighter (and the earlier NAA design for WS-110). Engines able to cope with higher temperatures and widely varying inlet air speeds were also under design, allowing for sustained supersonic speeds. By March 1957, engine development and wind tunnel testing had progressed such that the potential for all-supersonic flight appeared feasible – the cruise-and-dash approach that had resulted in huge designs was no longer needed.[17]



The project decided that the aircraft would fly at speeds up to Mach 3 for the entire mission, instead of a combination of subsonic cruise and supersonic dash of the aircraft designs in the previous year. Zip fuel was to be burned in the engine's afterburner to increase range.[17][19] Both North American and Boeing returned new designs with very long fuselages and large delta wings. They differed primarily in engine layout; the NAA design arranged its six engines in a semi-circular duct under the rear fuselage, while the Boeing design used separate podded engines located individually on pylons below the wing.[16]



NAA's final WS-110A proposal, built as the XB-70

North American had scoured the literature to find any additional advantage. The company found the relatively-unknown compression lift concept, which used the shock wave generated by the nose or other sharp points on the aircraft as a source of high pressure air.[20] By carefully positioning the wing in relation to the shock, the shock's high pressure could be captured on the bottom of the wing and generate additional lift. To take maximum advantage of this effect, they redesigned the underside of the aircraft to feature a large triangular intake area far forward of the engines, better positioning the shock in relation to the wing.[21] North American improved the design with a set of drooping wing tip panels that were lowered at high speed. This helped trap the shock wave under the wing between the downturned wing tips, and also added more vertical surface to the aircraft to improve directional stability at high speeds.[20] NAA's solution had an additional advantage, as it decreased the surface area of the rear of the wing when they were moved into their high speed position. This helped offset the rearward shift of the center of pressure, or "average lift point" with increasing speeds under normal conditions, causing an increasing nose-down trim. When the wing tips were drooped the surface area at the rear of the wings was lowered, moving the lift forward and counteracting this effect.[22]



The buildup of heat due to skin friction during sustained supersonic flight had to be addressed. During a Mach 3 cruise the aircraft would reach an average of 450 °F (230 °C), although there were portions as high as 650 °F (340 °C). NAA proposed building their design out of a sandwich panels, consisting of two thin sheets of stainless steel brazed to opposite faces of a honeycomb-shaped foil core. Expensive titanium would be used only in high-temperature areas like the leading edge of the horizontal stabilizer, and the nose.[23] For cooling the interior, the XB-70 pumped fuel en route to the engines through heat exchangers.[24]



On 30 August 1957, the Air Force decided that enough data was available on the NAA and Boeing designs that a competition could begin. On 18 September, the Air Force issued operational requirements which called for a cruising speed of Mach 3.0 to 3.2, an over-target altitude of 70,000-75,000 ft (21,300-22,700 m), a range of up to 10,500 mi (16,900 km), and a gross weight not to exceed 490,000 lb (222,000 kg). The aircraft would have to use the hangars, runways and handling procedures used by the B-52. On 23 December 1957, the North American proposal was declared the winner of the competition, and on 24 January 1958, a contract was issued for Phase 1 development.[13]



In February 1958, the proposed bomber was designated B-70,[13] with the prototypes receiving the "X" experimental prototype designation. The name "Valkyrie" was the winning submission in spring 1958, selected from 20,000 entries in a USAF "Name the B-70" contest.[25] The Air Force approved an 18-month program acceleration in March 1958 that rescheduled the first flight to December 1961.[13] But in the fall of 1958 the service announced that this acceleration would not be possible due to lack of funding.[26] In December 1958, a Phase II contract was issued. The mockup of the B-70 was reviewed by the Air Force in March 1959. Provisions for air-to-surface missiles and external fuel tanks were requested afterward.[27] At the same time North American was developing the F-108 supersonic interceptor. To reduce program costs, the F-108 would share two of the engines, the escape capsule, and some smaller systems with the B-70.[28]





Reconnaissance/Strike to search and knock out rail-based ICBMs[29] used refueling from tankers (at left) for two profiles.

• 7,748 nmi: high altitude USSR overflight descends for Diego Garcia landing (spirals depicted at right)

• 6,447 nmi: lands in Turkey after 1,200 nmi flight from target (mushroom clouds)

• 5,312 nmi: 856 nmi (1½ hr) Mach 0.95 "on-the-deck"approach to target

The "missile problem"



The B-70 was planned to use a high-speed, high-altitude bombing approach that followed a trend of bombers flying progressively faster and higher since the start of manned bomber use.[30] This helped the bomber evade enemy interceptor aircraft, the only effective anti-bomber weapon in the 1950s. Soviet interceptors during the late 1950s could not intercept the U-2 reconnaissance aircraft that could operate at very high altitudes.[31]



The introduction of the first effective anti-aircraft missiles by the late 1950s had seriously upset this equation.[32] By the 1960 downing of the U-2 flown by Gary Powers, military doctrine had shifted away from high-altitude supersonic bombing toward low-altitude penetration. By flying close to the Earth and hiding behind terrain, aircraft could dramatically shorten detection distances.[33] Designed for high-altitude flight, the B-70 lost this edge to improved Soviet high-altitude, anti-aircraft missiles.[32] The bomber lost its supersonic performance and range at low altitudes; it was limited to Mach 0.95 there.[10]



Adding to the program's problems, the zip fuel program was canceled in 1959.[6] After burning, the fuel turned into liquids and solids that increased wear on moving turbine engine components.[34] This by itself was not a fatal problem, however, as newly developed high-energy fuels like JP-6 were available that made up some of the difference. By filling one of the two bomb bays with a fuel tank, range was reduced only slightly, although payload space suffered.[35] Also, the F-108 program was canceled in September 1959, which ended the shared development that benefited the B-70 program.[28]



Downsizing, upswing, cancellation



At two secret meetings on 16 and 18 November 1959, General Twining recommended the Air Force's plan for the B-70 to reconnoiter and strike rail-mobile Soviet ICBMs, but General White admitted the Soviets would "be able to hit the B-70 with rockets" and requested the B-70 be downgraded to "a bare minimum research and development program" at $200 million for fiscal year 1960. President Eisenhower responded that the reconnaissance and strike mission was "crazy" since the nuclear mission was attacking known production and military complexes, and emphasized he saw no need for the B-70 since the ICBM is "a cheaper, more effective way of doing the same thing". Eisenhower also identified that the B-70 would not be in manufacturing until "eight to ten years from now" and "said he thought we were talking about bows and arrows at a time of gunpowder when we spoke of bombers in the missile age."[29][N 3] In December 1959 the Air Force announced the B-70 project would be cut to a single prototype, and most of the planned B-70 subsystems would no longer be developed.[36]



Then interest increased due the politics of presidential campaign of 1960. A central plank of John F. Kennedy's campaign was that Eisenhower and the Republicans were weak on defense, and pointed to the B-70 as an example. He told a San Diego audience near NAA facilities that "I endorse wholeheartedly the B-70 manned aircraft."[37] Kennedy also made similar campaign claims regarding other aircraft: near the Seattle Boeing plant he affirmed the need for B-52s and in Fort Worth he praised the B-58.[38]



The Air Force changed the program to full weapon development and awarded a contract for a XB-70 prototype and 11 YB-70s in August 1960.[36][39] In November 1960, the B-70 program received a $265 million appropriation from Congress for FY 1961.[40][41] Nixon, trailing in his home state of California, also publicly endorsed the B-70, and on 30 October Eisenhower helped the Republican campaign with a pledge of an additional $155 million for the B-70 development program.[42]



On taking office in January 1961, Kennedy was informed that the missile gap was an illusion.[43][N 4] On 28 March 1961,[44] after $800 million had been spent on the B-70 program, Kennedy canceled the B-70 Mach 3 manned bomber as "unnecessary and economically unjustifiable"[42] because it "stood little chance of penetrating enemy defenses successfully."[45] Instead, Kennedy recommended "the B-70 program be carried forward essentially to explore the problem of flying at three times the speed of sound with an airframe potentially useful as a bomber."[42]



After Congress approved $290 million of B-70 "add-on" funds to the President's 12 May 1960 modified FY 1961 budget, the Administration decided on a "Planned Utilization" of only $100 million of these funds. The Department of Defense subsequently presented data to Congress that the B-70 would add little performance for the high cost.[46] However, after becoming the new Air Force Chief of Staff in July 1961, Curtis LeMay increased his B-70 advocacy, including interviews for August Reader's Digest and November Aviation Week articles, and allowing a 25 February General Electric tour at which the press was provided artist conceptions of, and other info about, the B-70. Congress had also continued B-70 appropriations in an effort to resurrect bomber development. After the Secretary of Defense Robert McNamara explained again to the House Armed Services Committee (HASC) on 24 January 1962 that the B-70 was unjustifiable, LeMay subsequently argued for the B-70 to both the House and Senate committees—and was chastised by McNamara on 1 March. By 7 March 1962, the House Armed Services Committee (HASC)—with 21 members having B-70 work in their districts—had written an appropriations bill to "direct"—by law—the Executive Branch to use all of the nearly $500 million appropriated for the RS-70. McNamara was unsuccessful with an address to the HASC on 14 March, but a 19 March 1962 11th hour White House Rose Garden agreement between Kennedy and HASC chairman Carl Vinson retracted the bill's language[47] and the bomber remained canceled.[48]



Experimental aircraft



The two experimental XB-70As completed, were used for the advanced study of aerodynamics, propulsion, and other subjects related to large supersonic transports. These were named Air Vehicle 1 and 2 (AV-1 and AV-2). The production order was reduced to three prototypes in March 1961[49] with the third aircraft to incorporate improvements from the previous prototype.[50] The crew was reduced to only the pilot and co-pilot for the XB-70; the navigator and bomb-aimer were not needed.[51] XB-70 #1 was completed on 7 May 1964,[52] and rolled out on 11 May 1964 at Palmdale, California.[53] One report stated "nothing like it existed anywhere".[54][55] AV-2 was completed on 15 October 1964. The planned third prototype (AV-3) was canceled in July 1964 while under construction.[55] The first XB-70 had its maiden flight in September 1964 and flight testing followed.[56]



The XB-70 flight test data and materials development aided the later Rockwell B-1 Lancer supersonic bomber program, the US supersonic transport program and, through intelligence, the Soviet Tupolev Tu-144.[57][N 5] The development of the US U-2 and SR-71 reconnaissance aircraft along with the B-70 bomber led the Soviet Union to design and develop the MiG-25 interceptor.[58][59]



Design




Compression lift design of the XB-70 Valkyrie

The Valkyrie was designed to be a high-altitude bomber-sized Mach 3 aircraft with six engines. Harrison Storms shaped the aircraft[60] with a canard surface and a delta wing, which was built largely of stainless steel, sandwiched honeycomb panels, and titanium. The XB-70 was designed to use supersonic technologies developed for the Mach 3 Navaho, as well as a modified form of the SM-64 Navaho's all-inertial guidance system.[61]



The XB-70 used compression lift, which was generated from a prominent wedge at the center of the engine inlets that created a shock wave below the aircraft. The wing included inboard camber to more effectively use the higher pressure field behind the strong shock wave (the airflow at the XB-70 wing's leading edge was subsonic).[62] The compression lift increased the lift by five percent.[63] Unique among aircraft of its size, the outer portions of the wings were hinged, and could be pivoted downward by up to 65 degrees. This increased the aircraft's directional stability at supersonic speeds, shifted the center of lift to a more favorable position at high speeds, and strengthened the compression lift effect.[64] With the wingtips drooped downwards, the compression lift shock wave would be further trapped under the wings.



The XB-70 was equipped with six General Electric YJ93-GE-3 turbojet engines, designed to use JP-6 jet fuel. The engine was stated to be in the "30,000-pound class", but actually produced 28,000 lbf (124.6 kN) with afterburner and 19,900 lbf (88 kN) without afterburner.[65][66] The Valkyrie used fuel for cooling; it was pumped through heat exchangers before reaching the engines.[24] To reduce the likelihood of auto ignition, nitrogen was injected into the JP-6 during refueling, and the "fuel pressurization and inerting system" vaporized a 700 lb (320 kg) supply of liquid nitrogen to fill the fuel tank vent space and maintain tank pressure.[67]



Operational history



XB-70A Valkyrie on takeoff

Flight test program



The XB-70 flight test program was conducted from the maiden flight on 21 September 1964 through 6 August 1966. The first aircraft was found to suffer from weaknesses in the honeycomb panels, primarily due to inexperience with fabrication and quality control of this new material.[7]



The first flight test was marred: one engine had to be shut down; an undercarriage indication malfunction meant that the flight was flown with the undercarriage down, limiting speed to about half that planned.[68] On landing, the left-side rear wheels locked, the tires ruptured, and a fire started.[69]





XB-70 Performance[70]

Longest flight: 3:40 hours (on 6 January 1966)

Fastest speed: 2,020 mph (3,250 km/h) (on 12 January 1966)

Highest altitude: 74,000 ft (23,000 m) (on 19 March 1966)

Highest Mach number: Mach 3.08 (on 12 April 1966)

Sustained Mach 3: 32 minutes (on 19 May 1966)

Mach 3 total: 108 minutes/10 flights



The Valkyrie first became supersonic (Mach 1.1) on the third test flight on 12 October 1964, and flew above Mach 1 for 40 minutes during the following flight on 24 October. The wing tips were also lowered partially in this flight. XB-70 #1 surpassed Mach 3 on 14 October 1965 by reaching Mach 3.02 at 70,000 ft (21,300 m).[71]



Honeycomb panel deficiencies discovered on AV-1 were almost completely solved on the second XB-70, which first flew on 17 July 1965. On 3 January 1966, XB-70 #2 attained a speed of Mach 3.05 while flying at 72,000 ft (21,900 m). AV-2 reached a top speed of Mach 3.08 and maintained it for 20 minutes on 12 April 1966.[72] On 19 May 1966, AV-2 reached Mach 3.06 and flew at Mach 3 for 32 minutes, covering 2,400 mi (3,840 km) in 91 minutes of total flight.[73]



Flight research programs



After completion of the flight test program on 6 August 1966, flight research programs were conducted using the XB-70 with NAA support. The first was a joint NASA/USAF research program conducted from 3 November 1966 to 31 January 1967 for measuring the intensity and signature of sonic booms for the National Sonic Boom Program (NSBP). In 1966, AV-2 was selected for the program and was outfitted with test sensors. It flew the first sonic boom test on 6 June 1966, obtaining a speed of Mach 3.05 at 72,000 ft (21,900 m).[74] Sonic boom testing was planned to cover a range of overpressures on the ground similar but higher than the proposed American SST.[75] AV-2 crashed following a mid-air collision with an F-104 while flying a multi-aircraft formation.[76]



Sonic boom and later testing continued with XB-70A #1.[77] The second flight research program (NASA NAS4-1174) investigated "control of structural dynamics" from 25 April 1967 through the XB-70's last flight in 1969.[78][79] At high altitude and high speed, the XB-70A experienced unwanted altitude changes (porpoising).[80] NASA testing from June 1968 included two small vanes on the nose of AV-1 for measuring the response of the aircraft's stability augmentation system.[79][81]



Following the loss of AV-2, 33 research flights were completed by AV-1.[82] The XB-70's last supersonic flight took place on 17 December 1968. On 4 February 1969 AV-1 took its final flight to Wright-Patterson Air Force Base for museum display (now the National Museum of the United States Air Force).[83] Flight data was collected on this subsonic trip.[84] North American Rockwell completed a four-volume report on the B-70 that was published by NASA in April 1972.[85]



Variants

XB-70A Prototype of B-70. Two were built. AV-1, NAA Model Number NA-278, USAF S/N 62-0001, completed 83 flights spanning 160 hours and 16 minutes.[86][87]

AV-2, NAA Model Number NA-278, USAF S/N 62-0207, flew 46 times over 92 hours and 22 minutes, before it crashed in June 1966.[88]

XB-70B AV-3, NAA Model Number NA-274, USAF S/N 62-0208, Originally to be first YB-70A in March 1961, this advanced prototype was canceled while in manufacturing.[55][89] YB-70 Preproduction version with improvements based on XB-70s.[36][39] B-70A Planned bomber production version of Valkyrie.[7] A fleet of up to 65 operational bombers was planned.[90] RS-70 Proposed reconnaissance-strike version with a crew of four and in-flight refueling capability.[10]

Incidents and accidents



Incidents



On 7 May 1965, the divider separating the left and right halves of the engine inlet on XB-70A AV-1 broke off in flight and was ingested into the engines, damaging all six beyond repair.[54]



On 14 October 1965, AV-1 surpassed Mach 3, but heat and stress damaged the honeycomb panels, leaving 2 ft (0.6 m) of the leading edge of the left wing missing. These construction problems resulted in the imposition of a speed limit of Mach 2.5 on the first aircraft.[91]



Mid-air collision



The formation of aircraft shortly after the collision on 8 June 1966

On 8 June 1966, XB-70A #2 was in close formation with four other aircraft (an F-4, F-5, T-38, and F-104) for a photoshoot at the behest of General Electric, manufacturer of the engines of all five aircraft. With the photoshoot complete, the F-104 drifted into contact with the XB-70's right wing, flipped over and rolled inverted over the top of the Valkyrie, striking the vertical stabilizers and left wing of the bomber. The F-104 exploded, destroying the Valkyrie's rudders and damaging its left wing. With the loss of both rudders and damage to the wings, the Valkyrie entered an uncontrollable spin and crashed into the ground north of Barstow, California. NASA Chief Test Pilot Joe Walker (F-104 pilot) and Carl Cross (XB-70 co-pilot) were killed. Al White (XB-70 pilot) ejected, sustaining serious injuries, including one arm crushed by the closing clamshell-like escape capsule moments prior to ejection.[92]



The USAF summary report of the accident investigation stated that, given the position of the F-104 relative to the XB-70, the F-104 pilot would not have been able to see the XB-70's wing, except by uncomfortably looking back over his left shoulder. The report said that Walker, piloting the F-104, likely maintained his position by looking at the fuselage of the XB-70, forward of his position. The F-104 was estimated to be 70 ft (21 m) to the side of, and 10 ft (3 m) below, the fuselage of the XB-70. The report concluded that from that position, without appropriate sight cues, Walker was unable to properly perceive his motion relative to the Valkyrie, leading to his aircraft drifting into contact with the XB-70's wing.[81][93] The accident investigation also pointed to the wake vortex off the XB-70's right wingtip as the reason for the F-104's sudden roll over and into the bomber.[93]



Area 51 radar operator Barnes was monitoring the flight and recording the air traffic at the time of the accident and reports that Walker radioed just before the accident "I'm opposing this mission. It is too turbulent and it has no scientific value." Barnes says the vortex sucked him in. The recording was requested by Bill Houck of NASA and has since disappeared.[94]



Aircraft on display



Valkyrie AV-1 (AF Ser. No. 62-0001) is on display at the National Museum of the United States Air Force at Wright-Patterson AFB in Dayton, Ohio. The aircraft was flown to the Museum on 4 February 1969, following the conclusion of the XB-70 testing program.[95] Over the years the Valkyrie became the Museum's signature aircraft, appearing on Museum letterhead, and even appearing as the chief design feature for the Museum's restaurant, the Valkyrie Cafe.[96] As of 2011, the XB-70 was in the Museum's Research & Development Hangar where it is displayed alongside other experimental aircraft in the Museum's collection.[97]



Specifications (XB-70A)



Data from Pace,[98] USAF XB-70 Fact sheet[87]



General characteristics

Crew: 2

Length: 189 ft 0 in (57.6 m)

Wingspan: 105 ft 0 in (32 m)

Height: 30 ft 0 in (9.1 m)

Wing area: 6,297 ft² (585 m²)

Airfoil: Hexagonal; 0.30 Hex modified root, 0.70 Hex modified tip

Empty weight: 128,000 lb (58,100 kg)

Loaded weight: 534,700 lb (242,500 kg)

Max takeoff weight: 550,000 lb (250,000 kg)

Powerplant: 6 × General Electric YJ93-GE-3 afterburning turbojet Dry thrust: 19,900 lbf[65] (84 kN) each

Thrust with afterburner: 28,800 lbf[66] (128 kN) each



Internal fuel capacity: 300,000 lb (136,100 kg) or 46,745 US gallons (177,000 L)



Performance

Maximum speed: Mach 3.1 (2,056 mph, 3,309 km/h)

Cruise speed: Mach 3.0 (2,000 mph, 3,200 km/h)

Range: 3,725 nmi (4,288 mi, 6,900 km) on combat mission

Service ceiling: 77,350 ft (23,600 m)

Wing loading: 84.93 lb/ft² (414.7 kg/m²)

lift-to-drag: about 6 at Mach 2[99]

Thrust/weight: 0.314


See also



Aircraft in fiction, XB-70 Valkyrie

Pye Wacket



Related development North American XF-108 Rapier



Comparable aircraft Sukhoi T-4

Avro 730



References

Notes

1.^ Quote by Theodore von Kármán (1945): "The size and performance of the craft driven by atomic power would depend mainly on ... reducing the engine weight to the limiting value which makes flight at a certain speed possible."[4]

2.^ The NB-58 Hustler was used for XB-70 engine testing, and the TB-58 was used for XB-70 chase and training.

3.^ Following the 1963 formation of the National Supersonic Transport program, the 1964 Oklahoma City sonic boom tests "influenced the 1971 cancellation of the Boeing 2707 supersonic transport and led to the United States' complete withdrawal from SST design."

4.^ Wiesner… a member of Eisenhower's permanent Science Advisory Committee, explained that the missile gap was a fiction. The new president greeted the news with a single expletive "delivered more in anger than in relief". … Herken 1961, p. 140. This quote taken from Herken's interview with Wiesner conducted 9 February 1982.

5.^ In response to the British/French treaty of 29 November 1962 which would produce the supersonic Concorde airliner, US President Kennedy started the national Supersonic transport (SST) project in June 1963.[45] North American entered a design with some elements from the B-70, but it was eliminated from the SST airframe competition in June 1964.[45]

Citations

1.^ a b Knaack 1988, pp. 560–561.

2.^ York 1978, p. 70.

3.^ "B-70 Valkyrie." Globalsecurity.org. Retrieved: 24 May 2011.

4.^ a b von Kármán, Theodore. "Where We Stand: First Report to General of the Army H. H. Arnold on Long Range Research Problems of the Air Forces with a Review of German Plans and Developments". Atomic Energy for Jet Propulsion. Washington, D.C.: Government Printing Office, 22 August 1945.

5.^ Bikowicz, Brian D. "Atomic Powered Aircraft – Politics." Atomicengines.com. Retrieved: 24 May 2011.

6.^ a b c Schubert, Dave. "From Missiles to Medicine: The development of boron hydrides." Pioneer Magazine, March 2001.

7.^ a b c Jenkins 1999, Ch. 1.

8.^ Jenkins and Landis 2002, p. 9.

9.^ a b Jenkins and Landis 2002, pp. 9–10.

10.^ a b c B-70 Aircraft Report, Vol II. pp. II-2.

11.^ Knaack 1988, pp. 561, 566.

12.^ a b Pace 1988, p. 14.

13.^ a b c d Jenkins and Landis 2002, p. 17.

14.^ a b Jenkins and Landis 2002, pp. 13–14.

15.^ a b Knaack 1988, p. 563.

16.^ a b Jenkins and Landis 2002, pp. 15–16.

17.^ a b c d Jenkins and Landis 2002, pp. 14–15.

18.^ B-70 Aircraft Report, Vol. I., pp. I-34–I-38.

19.^ Conway 2005, p. 33.

20.^ a b Pace 1988, p. 16.

21.^ Winchester 2005, p. 187.

22.^ Talay, Theodore A., ed. "Dynamic Longitudinal, Directional, and Lateral Stability." Centennial of Flight Commission, 2003. Retrieved: 24 May 2011.

23.^ B-70 Aircraft Report, Vol. III., pp. II-31, III-141, III-210.

24.^ a b B-70 Aircraft Report, Vol. III., pp. III-496 to III-498.

25.^ Pace 1988, p. 17.

26.^ Knaack 1988, p. 566.

27.^ Jenkins and Landis 2002, p. 24.

28.^ a b Jenkins and Landis 2002, pp. 18, 26.

29.^ a b Goodpaster, Brig. General Andrew J., White House Office, Records of…Andrew J. Goodpaster…1952-1961, Dwight D. Eisenhower Presidential Library

June 23: Goodpaster (24 June 1959), Memorandum of Conference with the President: June 23, 1959 - 11:40 AM, Subject Series, Dept. of Defense Subseries, Box 1: Joint Chiefs of Staff (6), ""DECLASSIFIED…4/10/79""

November 16: Goodpaster (2 December 1959), Memorandum of Conference with the President: Monday, 16 November 1959, Augusta, Georgia, 8:30 a.m., Papers as President of the United States, 1953-1961 [Ann Whitman File]; DDE Diary Series Box No 46; Staff Notes—Nov 1959 (3), pp. 6–7 (B–70), ""DECLASSIFIED…8/23/79"" November 18: Goodpaster (20 January 1960), Memorandum of Conference with the President: November 18, 1959 - Augusta, Subject Series, Dept. of Defense Subseries, Box 4; Joint Chiefs of Staff (8) [September 1959-May 1960] & Papers as President of the United States, 1953-1961 [Ann Whitman File]; DDE Diary Series Box No 46, pp. 6–8 (B–70), ""DECLASSIFIED…1/18/81"" November 19: Goodpaster (21 November 1960), Memorandum for the Record: Meeting…Augusta, November 19, 1959 - from 8:30 a.m. to approximately 10:20 a.m., Papers as President of the United States, 1953-1961 [Ann Whitman File]; DDE Diary Series Box No 45; Staff Notes—Nov. 1959 (6), ""DECLASSIFIED…1/6/78""

30.^ Spick 1986, pp. 4-5.

31.^ Rich, Ben and Leo Janos. Skunk Works. Boston: Little, Brown & Company, 1994. ISBN 0-316-74300-3.

32.^ a b Jenkins 1999, p. 21.

33.^ Spick 1986, pp. 6–7.

34.^ Jenkins and Landis 2002, p. 98. Quote: "deleterious to metallic components".

35.^ Jenkins and Landis 2002, pp. 25–26.

36.^ a b c Jenkins and Landis 2002, p. 26.

37.^ Zuckert, Eugene M. "The Service Secretary: Has He a Useful Role?" Foreign Affairs, April 1966. Retrieved: 8 December 2008.

38.^ Kennedy, John F. "Speech of Senator John F. Kennedy, Civic Auditorium, Seattle, WA." The American Presidency Project at ucsb.edu. Retrieved: 30 May 2011.

39.^ a b Taube, Vol I, pp. I-29, I-31, I-37, I-38, I-47.

40.^ Jenkins and Landis 2002, pp. 26–27.

41.^ York 1978, p. 56.

42.^ a b c Kennedy, John F. "Remarks of Senator John F. Kennedy, Horton Plaza, San Diego, CA , November 2, 1960." The American Presidency Project at ucsb.edu. Retrieved: 6 April 2009.

"1961 Budget Message." Kennedy Archives, 28 March 1961, pp. I-38.

43.^ Preble, Christopher A. "Who Ever Believed in the 'Missile Gap'?: John F. Kennedy and the Politics of National Security." Presidential Studies Quarterly, December 2003, pp. 816, 819.

44.^ Knaack 1988, p. 569.

45.^ a b c Greenwood 1995, p. 289.

46.^ Builder, Carl H. Presentation to Congress by Alain Enthoven." The Icarus Syndrome: The Role of Air Power Theory in the Evolution and Fate of the U.S. Air Force. Cream Ridge, NJ: Transaction Publishers, 2002. ISBN 978-0765809933. Retrieved: 31 May 2011.

47.^ "House Unit 'Directs' Production of B-70.", The New York Times, 1 March 1962.

48.^ Pace 1988, pp. 20–21.

49.^ B-70 Aircraft Report, Vol. I. p. I-39.

50.^ Jenkins and Landis 2002, pp. 27–28.

51.^ Jenkins and Landis 2002, pp. 28, 73.

52.^ B-70 Aircraft Report, Vol. I. pp. I-39–I-44.

53.^ B-70 Aircraft Report, Vol. I. pp. I-41, I-88.

54.^ a b Boyne, Walter J. "The Ride of the Valkyrie." Air Force Magazine, June 2006. Retrieved: 29 October 2008.

55.^ a b c Jenkins and Landis 2002, p. 39.

56.^ Jenkins and Landis 2002, pp. 39–44.

57.^ Moon 1989, p. 92.

58.^ Pace, Steve. F-22 Raptor: America's Next Lethal War Machine. New York: McGraw-Hill, 1999. ISBN 0-07-134271-0.

59.^ Eden, Paul, ed. Encyclopedia of Modern Military Aircraft. New York: Amber Books, 2004. ISBN 1-90468-784-9.

60.^ Heppenheimer 2006, pp. 96, 112, 116.

61.^ von Braun 1975, p. 122.

62.^ Walker, Harold J. "Performance Evaluation Method for Dissimilar Aircraft Designs." NASA (Reference Publication 1042). Retrieved: 6 April 2009.

63.^ Jenkins and Landis 2002, p. 76.

64.^ B-70 Aircraft Study, Vol. III. p. III–162.

65.^ a b B-70 Aircraft Report, Vol. III. pp. III–476, III–479.

66.^ a b Jenkins and Landis 2002, pp. 83–84.

67.^ "XB-70 Interim Flight Manual." USAF, Series 25 June 65 (original publication: 31 August 1964), pp. 1-40B, 1-49.

68.^ "The B-70 Flies." Flight International, 1 October 1964, p. 577.

69.^ Pace 1990, pp. 56-57, 59.

70.^ Pace 1990, pp. 76-82.

71.^ Jenkins and Landis 2002, p. 50.

72.^ Jenkins and Landis 2002, p. 54.

73.^ Jenkins and Landis 2002, p. 56.

74.^ Jenkins and Landis 2002, pp. 61–62.

75.^ Jenkins and Landis 2002, pp. 62–63.

76.^ Pace 1990, pp. 62-68.

77.^ Pace 1988, pp. 62–69.

78.^ B-70 Aircraft Study, Vol. I. pp. I–32, I-43.

79.^ a b B-70 Aircraft Study, Vol. II. pp. II–5 to II-6.

80.^ Jenkins 1997, p. 45.

81.^ a b Jenkins and Landis 2002, pp. 60.

82.^ "XB-70A Valkyrie." Fact Sheets: Dryden Flight Research Center. Retrieved: 6 April 2009.

83.^ B-70 Aircraft Report, p. I-30.

84.^ Pace 1990, p. 71.

85.^ B-70 Aircraft Report, preface.

86.^ Jenkins and Landis 2002, p. 64.

87.^ a b "XB-70 Fact sheet." National Museum of the U.S. Air Force, 26 August 2009 . Retrieved: 31 May 2011.

88.^ Jenkins and Landis 2002, pp. 58, 93.

89.^ B-70 Aircraft Study, Vol. I. pp. I–40 to I-41.

90.^ B-70 Aircraft Report, Vol I, p. I–29.

91.^ Jenkins and Landis 2002, pp. 50–51.

92.^ Winchester 2005, p. 186.

93.^ a b Summary Report: XB-70 Accident Investigation. USAF, 1966.

94.^ Jacobsen 2011, pp 289-90.

95.^ United States Air Force Museum Guidebook 1975, p. 87.

96.^ "Valkyrie Cafe page." Air Force Museum Foundation. Retrieved: 23 December 2009.

97.^ "Research & Development Gallery." National Museum of the United States Air Force. Retrieved: 23 December 2009.

98.^ Pace 1990, p. 75.

99.^ Walker, Harold J. "Performance Evaluation Method for Dissimilar Aircraft Designs." NASA, RP 1042, September 1979.

Bibliography

Conway, Erik M. High-speed Dreams: NASA and the Technopolitics of Supersonic Transportation, 1945–1999. Baltimore: Johns Hopkins University Press, 2005. ISBN 0-8018-8067-X.

"Fundamentals of Aerospace Weapon Systems". Air University, Maxwell AFB, May 1961.

Greenwood, John T. (ed). Milestones of Aviation: National Air and Space Museum. Westport, CT: Hugh Lauter Levin Associates, Inc., 1995 (first published: 1989). ISBN 0-88363-661-1.

Heppenheimer, T. A. "Facing the Heat Barrier: A History of Hypersonics", part 1, part 2. NASA History Series, 2006. Retrieved: 6 April 2009.

Jenkins, Dennis R. B-1 Lancer, The Most Complicated Warplane Ever Developed. New York: McGraw-Hill, 1999. ISBN 0-07-134694-5.

Jenkins, Dennis R. Lockheed SR-71/YF-12 Blackbirds (WarbirdTech Series, Volume 10). North Branch, Minnesota: Specialty Press, 1997. ISBN 0-933424-85-X.

Jenkins, Dennis R. and Tony R. Landis. North American XB-70A Valkyrie WarbirdTech Volume 34. North Branch, Minnesota: Specialty Press, 2002. ISBN 0-58007-056-6.

Jenkins, Dennis R. and Tony R. Landis. Valkyrie: North American's Mach 3 Superbomber. North Branch, Minnesota: Specialty Press, 2005. ISBN 1-58007-072-8.

Lang, Walt N. United States Military Almanac. New York: Random House, 1989. ISBN 0-317-16092-7.

Knaack, Marcelle Size. Post-World War II bombers, 1945-1973. Office of Air Force History, 1988. ISBN 0-16-002260-6.

Machat, Mike. "XB-70 Valkyrie: Rollout and First Flights, May 1964-June 1966." Wings Volume 35, No. 8, August 2005.

Moon, Howard. Soviet SST: The Techno-Politics Of The Tupolev-144. Westminster, Maryland: Orion Books, 1989. ISBN 978-0517566015.

Pace, Steve. North American XB-70 Valkyrie, second edition. Blue Ridge Summit, PA: TAB Books, 1990. ISBN 0-8306-8620-7.

Pace, Steve. "Triplesonic Twosome". Wings Volume 18, No. 1, February 1988.

Spick, Mike. Modern Fighting Aircraft: B-1B. New York: Prentice Hall, 1986. ISBN 0-13-055237-2.

Taube, L.J., Study Manager. "SD 72-SH-0003, B-70 Aircraft Study Final Report, Vol. I." North American Rockwell via NASA, April 1972: Vol. II: Vol. III: Vol. IV.

von Braun Wernher (Estate of), Frederick I. Ordway III and David Jr. Dooling. Space Travel: A History. New York: Harper & Row, 1985, first edition, 1975. ISBN 0-06-181898-4.

Winchester, Jim. "North American XB-70 Valkyrie". Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. Kent, UK: Grange Books plc., 2005. ISBN 1-84013-309-2.

York, Herbert Jr. Race to Oblivion: A Participant's View of the Arms Race. New York: Simon & Schuster, 1978. ISBN 0-06-181898-4.

Jacobsen, A. (2011) Area 51. An uncensored history of America's Top Secret military base. Boston: Little, Brown pp. 289–90









The North American RS-70 Valkyrie

From Time:

Nation: RS-70: BUST OR SUPERPLANE?


Friday, Mar. 30, 1962


In the maneuvering last week between Congressman Carl Vinson and the Kennedy Administration, the bomber that was the cause of the fracas was all but ignored. What is the RS-70? Why did it stir such emotion in the Pentagon, the White House and the Congress? Is it a bust or a super plane?





THE RS-70 is the Air Force's new "reconnaissance-strike" version of the B70 superbomber that has been on the planning boards since 1953. It would be a truly revolutionary aircraft, flying at 2,000 m.p.h. at 80,000 ft. for distances, without refueling, of some 6,000 miles. The Air Force wants to spend $491 million next fiscal year (beginning July 1) on a program that would put the first RS-70s in operation by 1967, build up a fleet of 150 by 1970, at a total cost of some $10 billion. Secretary of Defense Robert Mc-Namara wants to spend $171 million next year on a throttled-back program aimed merely at developing three prototype RS-70s. The argument between the Air Force and McNamara stems from basically different concepts of national defense. Both sides claim that the other is absolutely wrong; in fact, neither side is totally right.



The Argument For. General Curtis LeMay, the Air Force Chief of Staff, flew B-17s against Europe, directed the B-29 attacks against Japan, developed the Strategic Air Command as the carrier of nuclear deterrent, and still has deep faith in manned aircraft no matter how fast the art of the missile has advanced. LeMay argues that a man can operate better in the inevitable confusion of combat than the robot brain of a missile. For the advantages of manned aircraft at whatever speed or altitude, he has only to point to the recent experiences of Astronaut John Glenn, who personally took the controls of Friendship 7 when the automatic equipment performed erratically. Even more important, if radar were to pick up signs of an attack on the U.S., an RS-70 could be sent on its way—and recalled later if the warning turned out to be false. No one can call back a missile: it goes or it stays.



The RS-70 advocates maintain that the nuclear deterrent must have the proper "mix" of bombers and missiles to overwhelm an enemy with a variety of weapons systems. If one does not work, another will—and the RS-70 is a whole new weapons system in itself. Those same advocates point out that production will stop this year on the Air Force's last two bombers—the 600-m.p.h. B-52 and the 1,300-m.p.h. B-58. If the RS-70 is held back, they say, the entire U.S. bomber fleet will eventually be obsolete.



The Air Force argues that the RS-70 would be a hard target to hit. Even if the Russians built a fighter that could fly 2,000 m.p.h., intercepting an RS-70 covering 30 miles a minute would be a tricky task. One of the RS-70's defenses against missiles would be highly secret electronic countermeasures. The Air Force admits that some RS-70s would be shot down; but many would get through to annihilate the enemy.

The Case Against. Defense Secretary McNamara trusts his charts, tables and economic projections just as much as General LeMay trusts his own experiences and intuition. McNamara's figures indicate that the money that would have to go into the RS-70 could be better spent elsewhere. For the $10 billion the Air Force wants to spend on RS-70s by 1970, McNamara says the U.S. could buy 2,000 Minuteman missiles, install them with all their equipment in concrete silos buried deep in the ground. What is more, it would cost $3 billion to maintain the RS-70 fleet for five years, v. $2 billion for the 2,000 Minutemen.




McNamara also argues that the RS-70 would be useless unless equipped with target-spotting radar and target-obliterating nuclear missiles that have not yet been designed—and might never be. The proposed radar would have to scan 100,000 sq. mi. an hour while the plane was traveling at 2,000 m.p.h. at 70,000 ft. To separate two points at that height, McNamara argued, would require a radar screen 15 ft. wide and 15 ft. high. By the late '60s, McNamara feels that the job of reconnaissance could be done by advanced versions of the Samos spy-in-the-sky satellite.



Despite these points, McNamara admits that changing circumstances might make the RS-70 necessary in the future. He now plans to spend an additional $52 million next fiscal year to see if the highly sophisticated equipment required for the RS-70 can be built. What is more, McNamara promised Vinson that he would spend at least some of the extra money voted by Congress on the aircraft "if technological developments advance more rapidly than we anticipated."



Both McNamara and the Air Force are persuasive in their arguments about the RS-70. By withdrawing his attempted congressional directive to the President, Carl Vinson staved off a potentially debilitating argument. Yet if Bob McNamara does not live up to his promise to reopen and restudy the issue of the RS-70, he may have history to answer to.


Read more: http://www.time.com/time/magazine/article/0,9171,895952,00.html#ixzz1OqUQsUtu





Read more: http://www.time.com/time/magazine/article/0,9171,895952,00.html#ixzz1OqU9I986



XB-70 Gallery, from the web: