B-83 training round
A B-83 training round designed to replicate the USAF’s B-83 freefall nuclear bomb. Designed to attack deeply-buried targets, this weapon could equip the B-21 in the future. (USAF)

“Ain’t a hope in hell, nothin’ gonna bring us down,” wrote Lemmy, the late lead vocalist of veteran heavy rock band Motorhead, for their December 1979 single Bomber. Lemmy’s confidence in aircraft invulnerability can only be realised through design and technology.

In October 2015, Northrop Grumman was awarded a development contract by the United States Air Force (USAF) to develop the first new strategic bomber for a generation. This award followed the publication of a Request for Proposals (RFP) by the US Department of Defence (DoD) for the new bomber in July 2014. A name has not yet been chosen for the new aircraft but its designation, the B-21 (as in 21st Century), was made public by the USAF at the Air Force Symposium held in Washington DC in February.

B-21 bomber
An artist’s impression of the USAF’s new B-21 bomber is the only visual reference to the aircraft. Its similarity to the existing B-2A Spirit strategic bomber is somewhat striking. (USAF)

Story So Far

The USAF has not take delivery of a new strategic bomber since Northrop Grumman’s B-2A Spirit stealth bomber was first delivered to the 509th Bomb Wing at Whiteman airbase, Missouri on 17 December 1993. The USAF currently possesses 21 examples, reinforced with 62 Rockwell Collins/Boeing B-1B strategic bombers. These latter aircraft are confined to a non-nuclear role following the signature of the Strategic Arms Reduction Treaty between the United States and the then Soviet Union on 31 July 1991, which removed the ability of this aircraft to carry Air-Launched Cruise Missiles (ALCMs). Today, the USAF strategic nuclear fleet includes the B-2A, plus 78 Boeing B-52H Stratofortress strategic bombers.

The USAF made efforts to enhance its strategic bomber force during the interim period between the B-2A’s entry into service and today via the Lockheed Martin FB-22A. The manufacturer launched an initiative in 2002 to examine the feasibility of developing a medium bomber variant of its F-22A Raptor air superiority fighter, with the intention of revitalising the role which had been played by the USAF’s General Dynamics F/FB-111A/D/E/F/G medium bombers. However, the 2006 Quadrennial Defence Review, the main public document which outlines US military doctrine, cancelled the initiative, with no further movement on this front until the RFP of July 2014 (see above).

F-22A
The F-22A was to have extensively informed the design for the FB-22 medium bomber. However, this project never moved beyond the ‘paper aeroplane’ stage, effectively being cancelled. (USAF)

When development of the B-2A commenced during the administration of US President Jimmy Carter in the late-1970s/early 1980s, via the Advanced Technology Bomber (ATB) programme, the chief concern for US strategists was the threat posed by Soviet mobile Intercontinental Ballistic Missiles (ICBMs). Such weapons included the Votkinsk Machine Building Plant RT-2PM Topol mobile ICBM (which remains in service), which had commenced development in 1977, and the RT-23 Molodets ICBM which was designed to be carried, and launched, from a special train. Both these weapons created significant concerns for defence planners as they were designed to remain mobile and hence increase their survivability relative to fixed ICBM silos. The Soviet Union’s land mass was 22 million square kilometres (8.4 million square miles), and locating and striking such targets had been likened to hunting a drifting needle in a haystack. This requirement was met by the B-2A’s Raytheon AN/APQ-181 radar which supported precision targeting using its Ka-band (33.4-36 Gigahertz) transmission frequencies which are particularly suitable for detecting and depicting targets in great detail.

This radar also supports terrain-following flight which would be essential should the B-2A ever have to hunt and destroy its targets in the Soviet Union. For its mission, the B-2A would have been flying through arguably the world’s most heavily-defended airspace, therefore its ability to evade radar would be essential. This requirement was what earned the B-2A its ‘Stealth Bomber’ nickname, and its most recognisable feature, its strange, sleek, flying-wing boomerang design. The aircraft’s shape and its use of carbon fibre provide it with a Radar Cross Section (RCS) of 0.01 metres (0.64 feet). It is important to note that the B-2A is not invisible to radar, but merely difficult to detect, and importantly, hard to pinpoint with either an Active- or Semi-Active Radar Homing (ARH/SARH) Surface-to-Air or Air-to-Air Missile (SAM/AAM). Yet the fuselage configuration is only part of the story. The aircraft is equipped with the Lockheed Martin AN/ZSR-63 Defensive Aids Subsystem. Details regarding the AN/ZSR-63 are understandably vague, although it is thought to encompass an active radar cancellation technique by which incoming radar transmissions are detected and analysed, and then retransmitted, possibly without Dopplar Shift (the phenomena where a radar transmission changes its frequency slightly after it is reflected from an object). The ability to manipulate Dopplar Shift may deceive a radar operator as to the position of the aircraft, or its speed, presuming that they are able to discern the small radar echo which the B-2A will present. Last, and by no means least, defensive flight profiles, such as terrain-following, and terrain masking help to obscure the aircraft from a radar’s gaze.

B-21
The B-21 will be the first new strategic bomber to enter USAF service in a generation, since the B-2A pictured here. (USAF)

A2/AD

These characteristics made the B-2A arguably the most advanced bomber designed during the Cold War, a conflict in which it never served. The aircraft entered service following the collapse of the USSR in December 1991. Yet this did not prevent the USAF employing the aircraft, and its useful low observable characteristics in successive conflicts since then. Although its role has been confined to the delivery of conventional ordnance, it earned its spurs on 24 March 1999 when the aircraft attacked several targets in Serbia in support of Operation ALLIED FORCE, the US-led air campaign against Serbia to stop ethnic cleansing in the Balkans region of Kosovo. Since then, the aircraft has participated in US-led operations in Iraq, Afghanistan and most recently Libya in 2011. Ultimately, the B-2A was designed with one potential conflict in mind, a nuclear war against the USSR and Warsaw Pact, but found itself in a more complex geopolitical environment, in which it has acted with aplomb.

The USAF is keeping the fluid geopolitical environment in mind as it develops the B-21 for tomorrow’s missions. “The B-21 Bomber will provide the ability to penetrate modern air defences to accomplish objectives despite an Anti-Access/Area-Denial (A2/AD) environment,” notes Major Robert Leese, a USAF spokesperson. A2/AD is a major concern for the USAF. Previous and potential US adversaries have witnessed the ability of this aircraft to slip through their defences and then hit high value targets, sometimes destroying or severally degrading ground-based air defences to allow oncoming strike packages of aircraft to attack other targets with relative impunity. Such concerns have manifested themselves in the development of new systems such as the Almaz-Antey S-400 Triumf SAM system which is entering service in Russia, and which is being exported to the People’s Republic of China (PRC). The S-400 has yet to be encountered in combat, and is widely respected by the pilots who may have to conduct sorties in its locale. The S-400’s 91N6E ground-based air surveillance radar can detect targets with an RCS of 0.4m (1.4ft) at 124 nautical miles/nm (230 kilometres/km), while its SARH/ARH 40N6 SAMs have a range of 215.9nm (400km). In the air domain, new fifth generation air superiority fighters such as the Sukhoi PAK-FA and MiG LMFS, both under development in Russia, plus the PRC’s Shenyang J-31, could all potentially contest airspace.

In fact, Maj. Leese continues, A2/AD is at the core of the B-21’s design requirement. “The need for the B-21 is grounded in a move … to a more A2/AD philosophy.” Therefore, a “B-21 bomber capable of operating in an anti-access/area-denial environment, possibly launched from the (Continental United States), is necessary to hold targets of all types at risk.” The USAF plans to employ the B-21 to hold targets at risk, and to strike them if necessary, using both conventional and nuclear ordnance. Unlike the B-1B which abandoned its nuclear obligations (see above), the B-21 will “will support the nuclear triad providing a visible and flexible nuclear deterrent capability,” Maj. Leese continues. This nuclear triad includes US Navy ‘Ohio’ class nuclear-powered ballistic missile submarines (expected to be replaced next decade) and silo-based Boeing LGM-30G Minuteman-III ICBMs. 

B-83 training round
A B-83 training round designed to replicate the USAF’s B-83 freefall nuclear bomb. Designed to attack deeply-buried targets, this weapon could equip the B-21 in the future. (USAF)

In terms of weapons, the air component of this triad currently includes B-61 Mod.3/4/7/11 variable-yield and B-83 variable-yield freefall nuclear bombs. The B-61 Mod.3/4/7/11 is currently receiving a ‘make-over’ via the B-61 Mod.12 programme which will lower the weapons’ yield, while improving its accuracy with the addition of a 50 kiloton (50000 tonnes of conventional explosive) physics package and an accuracy of 30 metres (98 feet). This weapon would have the asset of producing comparatively less radioactive fallout than legacy B-61 bombs, which have a selectable yield of 0.3, 1.5, five, ten, 45, 60, 80 or 170 kilotons, while the B-61 Mod.11 can select four yield options up to 340 kilotons. Production of the B-61 Mod.12 is expected to commence in circa 2020, with the US Department of Defence potentially receiving up to 500 of the new weapons which will replace the B.61 Mod.3/4/7 weapons, leaving the B-61 Mod.11 which is effectively a B-61 Mod.7 weapon designed to penetrate the ground to destroy deeply-buried targets, as the only other freefall nuclear bomb in service, given that the B-83 stockpile is expected to be reduced, if not completely eliminated, next decade.

B-61 nuclear bomb training rounds
B-61 nuclear bomb training rounds are pictured here. This weapon is undergoing an extensive modernisation and will almost certainly equip the B-21 in the future. (USAF)

However, the B-21 may also carry nuclear stand-off weapons in the form of the Long-Range Stand-Off (LRSO) ALCM which could replace the existing nuclear-armed Boeing AGM-86B ALCM currently deployed on the B-52H. The LRSO is also expected to be procured in a conventional version to replace the AGM-88C/D which, together with the nuclear-armed AGM-88B, is expected to leave service in circa 2030. A contract award for the development of the LRSO is expected in 2018 with media reports stating that up to 1000 of these weapons could be procured. Reports in March stated that an RFP for the LRSO is expected to be issued by the DoD by this June, with Boeing, Lockheed Martin, Northrop Grumman and Raytheon all vying to develop the weapon.

The USAF has then set itself an ambitious task. According to Maj. Leese, it plans to procure 100 of the new aircraft. Ominously, the USAF had originally requested 132 B-2A aircraft, although this was reduced to 76 by the then secretary of defence Richard Cheney in 1989, before being downsized once again to 20 aircraft, plus one test example, the current size of the fleet and the fall of the Soviet Union giving the perfect raison d’etre for reducing the number of aircraft to be procured. Yet geopolitical realities were not the only factor. Cost was another dominant motivation. The B-2A was never going to be an inexpensive aircraft to develop. In 2015 US dollars, the aircraft’s unit cost is $1.1 billion and the USAF is very keen to ensure that such costs are not incurred by the B-21 programme as it unfolds. It has set itself a target of an Average Procurement Unit Cost (APCU) of $564 million at 2016 values based upon a procurement of 100 aircraft, states Maj. Leese, although this could increase if fewer aircraft are ordered. Current USAF funding covers the Engineering and Manufacturing Development (EMD) phase of the LRS-B (Long Range Strike Bomber) programme which encompasses the B-21 initiative. The contract awarded to Northrop Grumman on 27 October 2015, worth $21.4 billion, is part of the EMD initiative, with the overall EMD phase, which also includes the procurement of the first five production lots of aircraft, a total of 21 airframes, being worth $23.5 billion in 2016 values.

The Requirement

The USAF has shied away from providing specific dates, although Maj. Leese has stated that an Initial Operational Capability (IOC) for the aircraft is envisaged for the mid-2020s, while the projected first flight and in-service date for the aircraft is being kept classified. An IOC of one decade seems quite an ambitious schedule, although Maj. Leese argues that the USAF has worked to ‘de-risk’ the initiative. “Over the past three years the (LRS-B) programme office (which oversees the programme for the USAF) has worked closely with industry to ensure designs and requirements remain stable … the programme has invested circa $1.9 billion in risk reduction activities. The programme office has completed preliminary design reviews and manufacturing readiness reviews to establish a higher level of technology maturity than any new developmental aircraft programme to date. Platform designs are now at the subsystem level: this provides … confidence in the areas of overall structure, electronics, hydraulics, engines, air data systems and low-observable technology.” Indeed, a number of other companies are involved as subsystems suppliers for the B-21 programme, notably BAE Systems, GKN Aerospace, Janicki Industries, Orbital ATK, Pratt and Whitney, Rockwell Collins, and Spirit Aerosystems. Moreover, the USAF has designed the aircraft to be ‘future proofed’ to an extent using open architecture via the so-called Air Force Open Mission System standard “to be able to evolve and integrate new technology and respond to future threats across the full spectrum of operations,” Maj. Leese adds.

The Debate

Ultimately, is the USAF’s desire of a 100 bomber fleet, ready to enter service from the middle of next decade, capable of defeating contemporary and future threats for a unit price of circa $564 million achievable? Douglas Barrie, aerospace analyst at the International Institute of Strategic Studies, a think tank, believes that it may be. Although developing a new military aircraft can take, “longer than you thought, and cost much more, it does not appear that the air force is starting with a blank sheet of paper.” Whereas the B-2A was a radically new design, despite the research already performed in the United States on flying wing designs, and low RCS techniques, the realisation of the B-21 comes at a period in USAF history, where the force has already commissioned and operated several low RCS designs including the Lockheed Martin F-117A Nighthawk ground attack aircraft, the F-22A and the Lockheed Martin F-35A Lighting-II fighter, not to mention the B-2A and the B-1B, also an aircraft with low observable characteristics, and highly classified programmes such as the Northrop Grumman RQ-180 unmanned aerial vehicle developed for reconnaissance. The existence of such initiatives means that “there is a substantial amount of research and development which has already gone on in the classified world. This means that inevitably there is more of a corporate body of knowledge on low observable technology available to the USAF.” Richard Aboulafia, vice president of analysis at the Teal Group, a research company, concurs, stating that previous experience illustrates that the air force “has an idea on how to build an aircraft like this.”

F-117A Nighthawk
Aircraft such as the F-117A Nighthawk are one of several low observable aircraft designs the USAF has adopted in the past decades, greatly enhancing its corporate knowledge on stealth characteristics. (USAF)

However, the acquisition will be at the mercy of the fiscal situation. Defence expenditure is in the doldrums in the US, as much as it is in Europe. “As a very expensive new-start acquisition effort, the B-21 programme will find itself in a fierce competition for scarce funding resources with other big ticket military procurement efforts such as the F-35A and the Boeing KC-46A tanker,” states Ray Jaworowski, senior aerospace analyst at Forecast International, a research company. “It would not be a surprise if budgetary stringencies result in the 100-bomber goal being reduced to … around 80 aircraft or so. Of course, reducing the total buy would result in a rise in the per-aircraft cost, so the cost savings from such a move would be less than what some may surmise.” Any funding issues could also have an effect on the schedule, Mr. Jaworowski adds. “USAF plans call for the B-21 to be fielded in the mid-2020s. Budgetary problems could well push the B-21 programme schedule to the right or, in a very worst case, even result in its eventual cancellation. At this point, cancellation seems unlikely, but schedule delay is a real possibility.”

Budgets are, of course, a moveable feast states Mr. Aboulafia, and there are no guarantees that the US DoD will not shrink the money available to the B-21 initiative in the future. “The aircraft’s unit price is probably feasible given the size of the procurement, but the size of the procurement depends on the size of the budget,” he cautions. The USAF has, he states, three main programmes (including the B-21), the F-35A and the KC-46A tanker. Although KC-46A funding is effectively ring-fenced by the DoD, this is not the case for the F-35A meaning that there is the danger of F-35A procurement competing with the B-21 acquisition. That said, given the age of the current strategic bomber fleet, the USAF has little choice but to replace these aircraft. “They really need this type (B-21) of aircraft, and there are not a lot of alternatives.” Mr. Aboulafia also has concerns regarding the aircraft’s design. Although the USAF has not released any specific details regarding the aircraft’s specifications the airframe is thought to be of a smaller size than the B-2A. “The biggest thing that concerns me is that the smaller size implies less range. That implies the USAF will place a premium on tanker usage to keep the aircraft aloft. However, much of the Chinese investment into A2/AD technologies is aimed at targeting force multiplying assets such as tankers.”

Currently, the air force has stated that it wishes to acquire 100 of the new aircraft, but there is every chance that additional platforms could be ordered over and above this number, particularly if the air force and Northrop Grumman is able to keep costs down while delivering a capable aircraft. Mr. Barrie believes that the design could, for example, be spun out into a reconnaissance aircraft, with the possibility of this platform being uninhabited, although the continuing deterrence mission makes it essential that a crew remain in the cockpit as far as the B-21 is concerned. In the past, bombers have provided the basis for reconnaissance platforms, for example, eight of the Royal Air Force’s erstwhile Avro Vulcan B.Mk.2 strategic bombers were converted for maritime reconnaissance.

Ultimately, Mr. Aboulafia argues that the B-21 imitative is feasible “as long as the funding is there and the schedule adhered to.” Cautious optimism then, from the air force, industry and air power experts, seems to characterise the outlook for the development and introduction of the B-21 bomber. The air force and industry certainly has its work cut out to develop the new aircraft, but to date both parties have also shown that they have quiet optimism that the programme will reach that holy grail of defence procurement, to meet the requirement on time, and on, or preferably under, budget.

by Thomas Withington