from Air Force Magazine:
In fact, the B-52H (dating to 1962) and B-1B (built in the mid-1980s) are planned to stay in service through 2040, and the B-2 (built in the 1990s) is slated to serve through 2058. Although predicting viability decades into the future is inherently risky, the actual service lives of all these aircraft could potentially exceed even those dates.
Based on the engineering forecasts, the toughness of the bombers’ original construction—all were built to function in the vicinity of nuclear blasts and shock waves—and their actual usage, Miller said, "Nothing I have seen says our bomber fleet is going to have any issues" reaching its planned retirement dates.
Likewise, changing out certain line replaceable units (LRUs) takes far less time now. It used to require breaking into the stealth shell, then replacing surface treatments in a process that took 72 hours to apply and cure. That’s been whittled down to less than an hour by the installation of stealthy panels and better surface treatments, Mazur reported.
The B-1B is regarded by its pilots as a "fighter on steroids," having supersonic speed and high agility, in addition to a payload exceeding that of the B-2 or B-52. Operating from a forward location in the Middle East, B-1Bs have orbited over Afghanistan, delivering precision guided munitions at record speed when ground forces request support. With a large payload and the ability to loiter for extended periods, the B-1B has seen heavy service in Southwest Asia.
To enhance its combat capabilities for the future, USAF is pursuing what Greenwell called "16-carry" launchers in the internal bays that will increase the loadout to as many as three times existing limits for individual weapons, using the 500-pound JDAM and the Small Diameter Bomb.
The Air Force has often considered replacing the B-52’s Pratt & Whitney TF33 engines. The most recent estimate pegged the cost of replacing them at $50 million per aircraft for USAF’s 74 B-52Hs. But they continue to serve without excessive problems. Oathout said P&W has done numerous evaluations on the type and has concluded "you could support these engines for many years."
March 2012
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Old Bombers, New Again
Can the Air Force get 30 to 50 more years out of the bombers it already has?
Long-range strike is one of the core missions of the Air Force, but USAF’s inventory of bombers is, by any measure, old. A new bomber program is on the books, but the aircraft won’t arrive for another 15 years or so, and even when it does, it could take decades to build a fleet of the necessary size. Can the legacy B-52s, B-1Bs, and B-2s physically last and continue to be credible weapons until the new bomber takes over?
The answer, Air Force and industry officials insist, is yes—and with time to spare.
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Maintainers swarm over a B-2 bomber. Keeping the nation’s premier penetrating bombers combat ready is a constant challenge. (ANG/DOD photo) |
However, the business of putting iron on target well behind enemy lines is getting tougher by the day. To remain credible, the bomber fleet will have to continue to evolve, said Lt. Gen. Christopher D. Miller, deputy chief of staff for strategic plans and programs.
The bomber flight plan, Miller said, has three elements to it. "One is keeping the airplanes structurally and otherwise safe and effective to fly," he said, followed by "keeping them tactically relevant with equipment upgrades ... and weapons," and finally, integrating the bombers into the overall concept of operations in a way that makes sense.
The bombers will have to be "complementary" to each other and to the rest of the combat air forces, Miller said, warning against considering any platform in isolation from the rest. The bombers will enable other combat systems and in turn be enabled by them, he said.
"For the toughest threat environments," Miller said, the fleet will increasingly rely on standoff weapons—missiles that the bombers can launch from outside the reach of an adversary’s defense systems.
"That’s not new," he said. "There’s always that balance of the cost of a standoff weapon and the advantages of being able to get the platform in closer proximity to the target." However, he said the Air Force has "shown a commitment over time" to choosing the right mix of weapons for its various platforms and giving combat commanders the effects they require. "That will not change," he said.
The bombers have undergone numerous changes over the years to make them relevant to their evolving missions, Miller said, and that approach will continue "for the foreseeable future."
"We’ve taken the B-1, for example, from a nuclear-only airplane to something that’s carrying Sniper pods, dropping [Joint Direct Attack Munitions] over Afghanistan."
Similarly, the Air Force has taken the B-52 from "a high-level-only airplane all the way through the Vietnam era of conventional bombs to a pod-equipped, [close air support]-capable plane that has been structurally updated through its lifetime," he said. All the aircraft have received modifications to make them compatible with updated international air traffic and navigation norms.
Structurally, the Air Force has closely monitored the health of its bombers and has done fleet viability analyses to gauge their potential longevity.
"That rolls in the durability testing, the component testing, the engineering projections, and it’s pretty exhaustive." The process—which tracks the individual bombers and their idiosyncrasies by tail number—"gives us a recurring snapshot of how ... these platforms [are] doing."
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L-r: A B-2, B-52, and B-1 fly in formation. All three types are expected to keep flying for decades to come. (USAF photo by SSgt. Samuel Rogers) |
The three bombers are very different machines with diverging missions, however, and each will get a tailor-made program of changes and improvements to maximize its contribution to the combat air forces.
B-2 Spirit: The Penetrator
The first B-2 was delivered for flight test in 1988 and reached initial operational capability in 1997. Fifteen years later, the stealth bomber continues to be the "tip of the spear" in major military operations, noted Dave Mazur, Northrop Grumman’s B-2 program chief.
It was the B-2 that made the opening attacks in the recent Libya campaign and before that, in Afghanistan and the Balkans. Air Force leaders say it will continue to be the nation’s premiere bomber for years to come.e.
There are only 20 B-2s in service. A total of 21 were built, but one was lost in a 2008 crash, and another was severely damaged in a 2010 engine fire that will keep it sidelined for up to two more years. Besides that, there are usually three B-2s undergoing programmed depot maintenance (PDM) at Northrop Grumman’s Palmdale, Calif., facilities.
Each B-2 is inducted for programmed depot maintenance every seven years. One of the B-2s is always engaged in test activities at Edwards AFB, Calif., so the number available for duty at any given time is only 14 or so airplanes. This constitutes a limited and precious capability.
The B-2 was not built like previous bombers. A large percentage of its weight is composites, and that’s a good thing in terms of the type’s longevity, Mazur said.
"The biggest downfall ... of an airplane is corrosion," Mazur said in December. During the B-2’s programmed depot maintenance (PDM) teardowns, maintainers just haven’t found a lot of corrosion, meaning the aircraft could have a long-extended service life. Besides that, the B-2 doesn’t maneuver violently and has a benign flight profile, so it won’t have to endure heavy dynamic loads that tend to induce stress fatigue.
Unlike previous bombers, which have a certain amount of play in their structures, the B-2 "is very rigid" to preserve its stealth and withstand the strains of flying in the vicinity of nuclear blasts, Mazur said. Collectively, these attributes give Northrop Grumman "very high confidence" the B-2 will easily reach its intended retirement date of 2058.
Over the past decade, the B-2 has been refined with a number of upgrades, many of them having to do with improving the resiliency and maintainability of its special stealth coatings and surface treatments. Thanks to a redesign, for example, fasteners near the leading edge of the airplane no longer need time-intensive and tricky puttying and taping; the shape and depth of the screw holes now make that unnecessary.
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A B-52 takes on fuel over the Pacific Ocean. Over the years the Air Force has replaced fuel bladders, hatches, windows, and other parts on the venerable aircraft. (USAF photo by MSgt. Cohen A. Young) |
Other improvements include Link 16 data transfer, UHF satellite communications, and additional weapons. Although the changes go beyond what was termed the Block 30 or all-up configuration of the B-2, Mazur noted, they don’t yet collectively add up to a nomenclature change to Block 40, although he’s sure that will eventually happen as further improvements are made.
The Air Force has a classified "capabilities flight plan" for the B-2 that tries to organize capability upgrades so they can be installed during PDM.
The Air Force recently declared the Massive Ordnance Penetrator—a conventional weapon with the explosive yield of a small atomic bomb—operational on the B-2, which can carry two MOPs. The B-2-massive penetrator combination will be USAF’s principal means of threatening hardened, deeply buried targets in denied airspace for years to come.
A radar upgrade on the B-2 is nearly complete, but some other improvements, such as a new antenna for Extremely High Frequency communications, have been tabled as the Air Force sorts out funding. A contract for replacement of the aft deck, which had been subject to cracking, was recently awarded to Northrop Grumman.
One promising near-term upgrade will be to wire the B-2 to be able to carry a variety of different kinds of weapons on internal rotary launchers, which will diversify the kinds of targets it can hit on a single mission and give combat planners dramatically greater flexibility, Mazur said.
Keeping the B-2’s mission capable rates at acceptable levels is a challenge chiefly because of parts, Mazur said. The LRUs "are 20 years old," and anything of that vintage "is obviously going to start failing more often." The answer is to design new, digital systems that will not only address maintenance concerns but add more capability, he said.
Parts shortages for the defensive management system are the most common reason the Air Force has to keep a B-2 on the ground, Mazur said. After installing EHF communications, modernizing the DMS is the top priority for keeping the B-2 credible, he said. The DMS upgrade is under contract and in progress.
Paul K. Meyer, head of Northrop Grumman’s Advanced Programs and Technology division, said there are many classified improvements that will allow the B-2 to penetrate enemy air defenses well into the future. Even as the bomber ages and enemy defenses improve, the B-2 may become a "Day 3" or "Day 10" weapon, but it remains "the best combat-proven weapon system" among the big bombers, he said.
B-1B Lancer: The Workhorse
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A B-1 touches down in Southwest Asia after performing a close air support mission in Iraq. (USAF photo) |
Although structural tests were done early in the B-1B program, a new static fatigue test will get under way shortly, said Boeing B-1 program manager Rick Greenwell. A B-1B taken from the Davis-Monthan AFB, Ariz., "Boneyard" will be broken up into a fuselage and wings and subjected to a torture test simulating more years of hard use. The wing will be inducted for the test in 2012 and finish in 2017, while the fuselage begins the test in 2014 and finishes in 2020.
"We think it can last out through 2050," or 10 years longer than the Air Force will require, Greenwell said.
The B-1B fleet has undergone some recent work to help it last. After problems with the dorsal longeron—the spine of the aircraft—Boeing is replacing the part and has done the work on 54 of the 66 aircraft in inventory. This one change alone will buy many years of service, Greenwell said. Another upgrade will reinforce the wing lower skins.
Operationally, "we are finishing up a tremendous amount of modifications" to make the B-1B more combat capable, he said. These include an updated inertial navigation system, now through development and entering production.
A radar improvement program will decrease the amount of maintenance needed on the aircraft, although the B-1 community is angling to replace the radar with a new active electronically scanned array (AESA) radar, which would drastically reduce maintenance and multiply the B-1B’s radar functions. That modification could start in 2014 and finish before the end of this decade.
Other improvements include data links and cockpit upgrades that will replace an awkward tangle of ad-hoc laptops and wires with a more operator-friendly, streamlined internal system.
"Sustainment is an issue," Greenwell said, since the B-1’s 1980s-vintage parts are running out and replacements are hard to get. The Air Force’s air logistics centers "do a good job" of anticipating parts issues and making sure they are available when aircraft enter programmed depot maintenance.
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The B-2 was first in for the opening attacks in the recent Libya campaign and, before that, in Afghanistan and the Balkans. (Northrop Grumman photo) |
B-52: The Survivor
The B-52’s mission has evolved many times since the type first flew in the 1950s, Miller said. It has gone from a high-altitude strategic bomber to an on-the-deck penetrator to a conventional bomb truck, a standoff cruise missile platform, and most recently, to a close air support aircraft. The fleet averages about 17,800 hours of service, but can go to 28,600 hours at least. The new goal is to get the B-52 to last until 2040—something prime contractor Boeing thinks may actually be a conservative figure.
"We don’t have to do anything until 2040" by way of a service life upgrade to keep the B-52 safe to fly, Boeing B-52 manager Scot Oathout said. The wings received a major structural upgrade to accommodate cruise missiles in the late 1970s, and that "wing beef-up" won’t have to be revisited until 2040.
The B-52 was "overdesigned," Oathout said, meaning its structure can stand far more than specified loads. The current fleet, all B-52Hs, sat alert for many years with much flying, and since then, they have operated at high altitude in a fairly "benign" flight profile without a lot of violent maneuvering, putting little stress on them.
Air Force Materiel Command tracks all the bombers by tail number, he said, so each aircraft gets virtually tailor-made service when it goes in for PDM.
Parts are an issue, Oathout admitted. While some can be taken from mothballed B-52s at Davis-Monthan, the preferred method is to temporarily use a Boneyard part but make a new one from scratch. The Air Force buys such parts in sufficient batches "to ensure a source of supply" for a number of years, Oathout said.
Over the years, he said, the Air Force has replaced fuel bladders, hatches, windows, and most recently, the B-52’s radomes. Boeing does analyses of components and systems and recommends to the Air Force when it will become more economical to replace systems than to try to keep supporting them.
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SSgt. Joshua Partin, with the 2nd Maintenance Squadron Fabrication Flight, walks the massive wing of a B-52 in its hangar at Barksdale AFB, La. (USAF photo by A1C Micaiah Anthony) |
In an austerity budget, spending billions to re-engine the B-52 is not likely. A key near-term improvement for the B-52 is the 1760 bus, which will allow the BUFF to carry all the most modern munitions—the Joint Direct Attack Munition, Joint Air-to-Surface Standoff Missile, and JASSM-ER (Extended Range)—on an internal rotary launcher. The move will yield better fuel economy from reduced drag, flexibility of mixed payloads, and less maintenance.
In fact, Oathout reported, USAF has designated 40 common strategic rotary launchers as "excess" to nuclear requirements and will dedicate them to strictly conventional missions.
The first increment on the CSRL software and integration plan will adapt the software for various Global Positioning System weapons such as JDAM and JASSM; "Increment 2 eventually gets to a mixed load," Oathout said, that would enhance the flexibility of the B-52 to carry a variety of weapons on each mission.
Another critical ongoing improvement is the Combat Network Communications Technology, or CONECT, upgrade, to give the aircraft a digital backbone and enhanced communications. It will put improved processors at each crew member’s station, provide color displays, and finally eliminate a jerry-rigged tangle of wires and laptops that has been cluttering the B-52’s cockpit for years. The B-52 has also been fitted with the Sniper targeting pod, giving it another imaging and targeting sensor at a low cost, Oathout said.
On the horizon is a potential new AESA radar, to vastly improve the B-52’s search and ground-mapping capability while giving it additional electronic warfare capability and reducing its electromagnetic signature. The radar would need to come along by the end of this decade to replace the 30-year-old model that is rapidly becoming "unsupportable," Oathout reported. An analysis of alternatives is under way, scrutinizing in-production radars that could provide an off-the-shelf solution.
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