Wednesday, July 31, 2013

Rockwell B-1 Lancer

Rockwell B-1 Lancer

The Rockwell (now part of Boeing) B-1 Lancer[N 1] is a four-engine variable-sweep wing strategic bomber used by the United States Air Force (USAF). It was first envisioned in the 1960s as a supersonic bomber with Mach 2 speed, and sufficient range and payload to replace the Boeing B-52 Stratofortress. It was developed into the B-1B, primarily a low-level penetrator with long range and Mach 1.25 speed capability at high altitude.
Designed by Rockwell International, the bomber's development was delayed multiple times over its history, as the theory of strategic balance changed from flexible response to massive retaliation and back again. Each change in stance changed the perceived need for manned bombers. The initial B-1A version was developed in the early 1970s, but its production was canceled, and only four prototypes were built. The need for a new platform once again surfaced in the early 1980s, and the aircraft resurfaced as the B-1B version with the focus on low-level penetration bombing. However, by this point development of stealth technology was promising an aircraft of dramatically improved capability. Production went ahead as the B version would be operational before the "Advanced Technology Bomber" (which became the B-2 Spirit), during a period when the B-52 would be increasingly vulnerable. The B-1B entered service in 1986 with the USAF Strategic Air Command as a nuclear bomber.
In the 1990s, the B-1B was converted to conventional bombing use. It first served in combat during Operation Desert Fox in 1998 and again during the NATO action in Kosovo the following year. The B-1B has supported U.S. and NATO military forces in Afghanistan and Iraq. The Lancer is the supersonic component of the USAF's long-range bomber force, along with the subsonic B-52 and Northrop Grumman B-2 Spirit. The bomber is commonly called the "Bone" (originally from "B-One"). With the retirement of the General Dynamics/Grumman EF-111A Raven in 1998 and the Grumman F-14 Tomcat in 2006, the B-1B is the U.S. military's only active variable-sweep wing aircraft. The B-1B is expected to continue to serve into the 2030s; the Next-Generation Bomber is to start supplementing the B-1B in the 2020s.


Background

Main article: North American XB-70 Valkyrie
The U.S. Air Force in 1955 issued requirements for a new bomber with the payload and range of the Boeing B-52 Stratofortress and the Mach 2 maximum speed of the Convair B-58 Hustler.[2] In December 1957, the U.S. Air Force selected North American Aviation's proposal to replace the B-52 with the B-70 Valkyrie.[3] The Valkyrie was a six-engine bomber that could reach Mach 3 speeds at high altitude (70,000 ft or 21,000 m)[4] to avoid interceptor aircraft, the only effective anti-bomber weapon in the 1950s.[5] Soviet aircraft were already unable to intercept the high-flying Lockheed U-2;[6] and the Valkyrie would fly at similar altitudes and much higher speeds.[5] By the late 1950s, however, anti-aircraft surface-to-air missiles (SAMs) could threaten high-altitude aircraft,[7] as demonstrated by the 1960 downing of Gary Powers's U-2.[8]
The USAF Strategic Air Command (SAC) began moving its bombers to low-level penetration before the U-2 downing. This tactic greatly reduces radar detection distances by use of terrain masking.[9] At that time SAMs were ineffective against low-flying aircraft.[9][10] Also during this era, low flying aircraft were difficult to detect by higher flying interceptors since their radar systems could not readily pick out opposing aircraft against the radar clutter from ground reflections. Planners outlined a series of low-level profiles for the B-70, but higher drag at low level limited the B-70 to subsonic speed while dramatically decreasing its range.[7] The result would be an aircraft with similar speed but less range than the B-52 it was meant to replace. Unsuited for this new role and because of a growing intercontinental ballistic missile (ICBM) force, the B-70 bomber program was canceled in 1961 by President John F. Kennedy,[5][11] and the two XB-70 prototypes were used in a supersonic research program.[12]
Although never intended for the low-level role, the B-52's flexibility allowed it to outlast its intended successor as the nature of the air war environment changed. The B-52's large airframe with internal room allowed the addition of improved electronic countermeasures suites.[13] During the Vietnam War the concept that all future wars would be nuclear was turned on its head, and the "big belly" modifications increased the B-52's total bomb load to 60,000 pounds (27,000 kg),[14] turning it into a powerful tactical aircraft which could be used against ground troops along with strategic targets from high altitudes.[10] The move to low-level penetration led to development of the supersonic F-111 fighter-bomber which used variable-sweep wings.[15]

Design studies and delays

The first post-B-70 strategic penetrator study was known as the Subsonic Low Altitude Bomber (SLAB), which was completed in 1961. This produced a design that looked more like an airliner than a bomber, with a large swept wing, T-tail and large high-bypass engines.[16] This was followed by the similar Extended Range Strike Aircraft (ERSA), which added a variable-sweep wing planform, something in vogue in the aviation industry. ERSA envisioned a relatively small aircraft with a 10,000 pounds (4,500 kg) payload and a range of 8,750 nautical miles (16,210 kilometres), with 2,500 nmi (4,600 km) being flown at low altitudes. In August 1963 the similar Low-Altitude Manned Penetrator (LAMP) design was completed, which called for an aircraft with a 20,000 pounds (9,100 kg) bomb load and somewhat shorter range of 7,150 nmi (13,240 km).[17][18]
These all culminated in the October 1963 Advanced Manned Precision Strike System (AMPSS), which led to industry studies at Boeing, General Dynamics, and North American.[19][20] In mid-1964, the USAF had revised its requirements and retitled the project as Advanced Manned Strategic Aircraft (AMSA), which differed from AMPSS primarily in that it also demanded a high-speed high-altitude capability, similar to that of the existing Mach 2 class B-58 Hustler.[21] Given the lengthy series of design studies, Rockwell engineers joked that the new name actually stood for "America's Most Studied Aircraft".[22][23]
The arguments that led to the cancellation of the B-70 program had led some to question the need for a new strategic bomber of any sort. The air force was adamant about retaining bombers as part of the nuclear triad concept that included bombers, ICBMs, and submarine-launched ballistic missiles (SLBMs) in a combined package that complicated any potential defense. They argued that the bomber was needed to attack hardened military targets and to provide a safe counterforce option because the bombers could be quickly launched into safe loitering areas where they could not be attacked. However, the introduction of the SLBM mooted the mobility and survivability argument, and a newer generation of ICBMs had the accuracy and speed needed to attack point targets. During this time, ICBMs were seen as a less costly option based on their lower unit cost,[24] but development costs were much higher.[7] Secretary of Defense Robert McNamara preferred ICBMs over bombers for the Air Force portion of the deterrent force[25] and felt a new expensive bomber was not needed.[26][27] McNamara limited the AMSA program to studies and component development beginning in 1964.[27]
Program studies continued; IBM and Autonetics were awarded AMSA advanced avionics study contracts in 1968.[27][28] McNamara remained opposed to the program in favor of upgrading the existing B-52 fleet and adding nearly 300 FB-111s for shorter range roles then being filled by the B-58.[10][27] He again vetoed funding for AMSA aircraft development in 1968.[28]



B-1A program

President Richard Nixon re-established the program after taking office, keeping with his administration's flexible response strategy that required a broad range of options short of general nuclear war.[29] Nixon's Secretary of Defense, Melvin Laird, reviewed the programs and decided to lower the numbers of FB-111s, since they lacked the desired range, and recommended that the AMSA design studies be accelerated.[29] In April 1969, the program officially became the B-1A.[10][29] This was the first entry in the new bomber designation series, first created in 1962. The Air Force issued a request for proposals in November 1969.[30]
A B-1A flying with its wings swept back, showing its underside
B-1A Prototype 4 showing its underside in 1981
The nose section of a B-1A on display with outline of the ejection capsule denoted
B-1A nose section with ejection capsule denoted. Three of the four B-1As were fitted with escape capsules.
Proposals were submitted by Boeing, General Dynamics and North American Rockwell in January 1970.[30][31] In June 1970, North American Rockwell's design was selected and was awarded a development contract.[30] The original program called for two test airframes, five flyable aircraft, and 40 engines. This was cut in 1971 to one ground and three flight test aircraft.[32] The company changed its name to Rockwell International and named its aircraft division North American Aircraft Operations in 1973.[33] A fourth prototype, built to production standards, was ordered in the fiscal year 1976 budget. Plans called for 240 B-1As to be built, with initial operational capability set for 1979.[34]
Rockwell's design featured a number of features common to 1960s U.S. designs. Among these was the use of a "crew capsule" that ejected as a unit during emergencies, which was introduced to improve survivability in the case of an ejection at high speed. Additionally, the design featured large variable-sweep wings in order to provide both high lift during takeoff and landing, and low drag during a high-speed dash phase.[35] With the wings set to their widest position the aircraft had considerably better lift and power than the B-52, allowing it to operate from a much wider variety of bases. Penetration of the USSR's defenses would take place at supersonic speed, crossing them as quickly as possible before entering into the less defended "heartland" where speeds could be reduced again.[35] The large size and fuel capacity of the design would allow this portion of the flight to be relatively long.
In order to achieve the required Mach 2 performance at high altitudes, the exhaust nozzles and air intake inlets were variable.[36] Initially, it had been expected that a Mach 1.2 performance could be achieved at low altitude, which required that titanium be used in critical areas in the fuselage and wing structure. The low altitude performance requirement was later lowered to Mach 0.85, reducing the amount of titanium and therefore cost.[32] A pair of small vanes mounted near the nose are part of an active vibration damping system that smooths out the otherwise bumpy low-altitude ride.[37] The first three B-1As featured an escape capsule that ejected the cockpit with all four crew members inside. The fourth B-1A was equipped with a conventional ejection seat for each crew member.[38]
The B-1A mockup review occurred in late October 1971.[39] The first B-1A prototype (serial no. 74-0158) flew on 23 December 1974. Three more B-1A prototypes followed.[40] As the program continued the per-unit cost continued to rise in part because of high inflation during that period. In 1970, the estimated unit cost was $40 million, and by 1975, this figure had climbed to $70 million.[41]

New problems and cancellation

In 1976, Soviet pilot Viktor Belenko defected to Japan with his MiG-25 "Foxbat".[42] During debriefing he described a new "super-Foxbat" (almost certainly referring to the MiG-31) that had look-down/shoot-down radar systems in order to attack cruise missiles. This would also make any low-level penetration aircraft "visible" and easy to attack.[43] Given that the B-1's armament suite was similar to the B-52, and it now appeared no more likely to survive Soviet airspace than the B-52, the program was increasingly questioned.[44] In particular, Senator William Proxmire continually derided it in public, arguing it was an outlandishly expensive dinosaur. During the 1976 federal election campaign, Jimmy Carter made it one of the Democratic Party's platforms, saying "The B-1 bomber is an example of a proposed system which should not be funded and would be wasteful of taxpayers' dollars."[45]
When Carter took office in 1977 he ordered a review of the entire program. By this point the projected cost of the program had risen to over $100 million per aircraft, although this was lifetime cost over 20 years. He was informed of the relatively new work on stealth aircraft that had started in 1975, and he decided that this was a better avenue of approach than the B-1. Pentagon officials also stated that the AGM-86 Air Launched Cruise Missile (ALCM) launched from the existing B-52 fleet would give the USAF equal capability of penetrating Soviet airspace. With a range of 1,500 miles (2,400 km), the ALCM could be launched well outside the range of any Soviet defenses and penetrate at low altitude just like a bomber, but in much greater numbers at a lower cost.[46] A small number of B-52s could launch hundreds of ALCMs, saturating the defense. A program to improve the B-52 and develop and deploy the ALCM would cost perhaps 20% of the price to deploy the planned 244 B-1As.[45]
On 30 June 1977, Carter announced that the B-1A would be canceled in favor of ICBMs, SLBMs, and a fleet of modernized B-52s armed with ALCMs.[34] Carter called it "one of the most difficult decisions that I've made since I've been in office." No mention of the stealth work was made public with the program being top secret, but today it is known that in early 1978 he authorized the Advanced Technology Bomber (ATB) project, which eventually led to the B-2 Spirit.[47]
Domestically, the reaction to the cancellation was split along partisan lines. The Department of Defense was surprised by the announcement; internal expectations were that the number of B-1s ordered would be reduced to around 150.[48] Congressman Robert Dornan (R-CA) claimed, "They're breaking out the vodka and caviar in Moscow."[49] In contrast, it appears the Soviets were more concerned by large numbers of ALCMs representing a much greater threat than a smaller number of B-1s. Soviet news agency TASS commented that "the implementation of these militaristic plans has seriously complicated efforts for the limitation of the strategic arms race."[45] Western military leaders were generally happy with the decision. NATO commander Alexander Haig described the ALCM as an "attractive alternative" to the B-1. French General Georges Buis stated "The B-1 is a formidable weapon, but not terribly useful. For the price of one bomber, you can have 200 cruise missiles."[45]
Flight tests of the four B-1A prototypes for the B-1A program continued through April 1981. The program included 70 flights totaling 378 hours. A top speed of Mach 2.22 was reached by the second B-1A. Engine testing also continued during this time with the YF101 engines totaling almost 7,600 hours.[50]

Shifting priorities

A right side view of a B-1A on the ground in 1984
A Rockwell B-1A in 1984
It was during this period that the Soviets started to assert themselves in several new theaters of action, in particular through Cuba during the Angolan Civil War starting in 1975 and the Soviet invasion of Afghanistan in 1979. U.S. strategy to this point had been focused on containing Communism and preparation for war in Europe. The new Soviet actions revealed that the military lacked capability outside these narrow confines.[51]
The army responded by accelerating its Rapid Deployment Forces concept but suffered from major problems with airlift and sealift capability.[52] In order to slow an enemy invasion of other countries, air power was critical; however the key Iran-Afghanistan border was outside the range of the U.S. Navy's carrier-based attack aircraft, leaving this role to the air force. Although the B-52 had the range to support on-demand global missions, its long runway requirements limited the forward basing possibilities.[53]
During the 1980 presidential campaign, Ronald Reagan campaigned heavily on the platform that Carter was weak on defense, citing the cancellation of the B-1 program as an example, a theme he continued using into the 1980s.[54] During this time Carter's defense secretary, Harold Brown, announced the stealth bomber project, apparently implying that this was the reason for the B-1 cancellation.[55]

B-1B program

On taking office, Reagan was faced with the same decision as Carter before: whether to continue with the B-1 for the short term, or to wait for the development of the ATB, a much more advanced aircraft. Studies suggested that the existing B-52 fleet with ALCM would remain a credible threat until 1985, as it was predicted that 75% of the B-52 force would survive to attack its targets.[56] After this, the introduction of the SA-10 missile, the MiG-31 interceptor and the first Soviet Airborne Early Warning and Control (AWACS) systems would make the B-52 increasingly vulnerable.[57] During 1981, funds were allocated to a new study for a bomber for the 1990s time-frame, this led to the Long-Range Combat Aircraft (LRCA) project. The LCRA evaluated the B-1, F-111 and ATB as possible solutions; an emphasis was placed on multi-role capabilities, as opposed to purely strategic operations.[56]
The first B-1B at its roll-out ceremony outside a hangar in Palmdale, California in 1984
First B-1B debuted outside a hangar in Palmdale, California, 1984
In 1981, it was believed the B-1 could be in operation before the ATB, covering the transitionary period between the B-52's increasing vulnerability and the ATB's introduction. Reagan decided the best solution was to procure both the B-1 and ATB, and on 2 October 1981 Reagan announced that 100 B-1s were to be ordered to fill the LRCA role.[35][58]
In January 1982 the U.S. Air Force awarded two contracts to Rockwell worth a combined $2.2 billion for the development and production of 100 new B-1 bombers.[59] Numerous changes were made to the design to make it better suited to the now expected missions, resulting in the new B-1B.[46] These changes included a reduction in maximum speed,[55] which allowed the variable-aspect intake ramps to be replaced by simpler fixed geometry intake ramps in the newer design. This reduced the B version's radar signature; the reduction in radar cross-section was seen as a good trade off for the speed decrease.[35] High subsonic speeds at low altitude became a focus area for the revised design,[55] and low-level speeds were increased from about Mach 0.85 to 0.92. The B-1B has a maximum speed of Mach 1.25 at higher altitudes.[35][60]
The B-1B's maximum takeoff weight was increased to 477,000 pounds (216,000 kg) from the B-1A's 395,000 pounds (179,000 kg).[35][61] The weight increase was to allow for takeoff with a full internal fuel load and for external weapons to be carried. Rockwell engineers were able to reinforce critical areas and lighten non-critical areas of the airframe, so the increase in empty weight was minimal.[61] In order to deal with the introduction of the MiG-31 and other aircraft with look-down capability, the B-1B's electronic warfare suite was significantly upgraded.[35]
B-1B with its wings swept back doing a banked turn during a demonstration
B-1B banking during a demonstration in 2004
Opposition to the plan was widespread within Congress. Critics pointed out that many of the original problems remained in both areas of performance and expense.[62] In particular it seemed the B-52 fitted with electronics similar to the B-1B would be equally able to avoid interception, as the speed advantage of the B-1 was now minimal. It also appeared that the "interim" time frame served by the B-1B would be less than a decade, being rendered obsolete shortly after the introduction of a much more capable ATB design.[63] The primary argument in favor of the B-1 was its large conventional payload, and that its takeoff performance allowed it to operate with a credible bombload from a much wider variety of airfields. The air force spread production subcontracts across many congressional districts, making the aircraft more popular on Capitol Hill.[56]
B-1A #1 was disassembled and used for radar testing at the Rome Air Development Center at the former Griffiss Air Force Base, New York.[64] B-1As #2 and #4 were modified to include B-1B systems. The first B-1B was completed and began flight testing in March 1983. The first production B-1B was rolled out on 4 September 1984 and first flew on 18 October 1984.[65] The 100th and final B-1B was delivered on 2 May 1988;[40] as a point of controversy, even before the last B-1B was delivered, the air force had determined that the aircraft was vulnerable to Soviet air defenses




Overview

A front view of a B-1B's nose showing its small canards
B-1B nose view with small triangular fins shown
The B-1 has a blended wing body configuration, with variable-sweep wing, four turbofan engines, and triangular fin control surfaces. The wings can sweep from 15 degrees to 67.5 degrees (full forward to full sweep). Forward-swept wing settings are used for takeoff, landings and high-altitude maximum cruise. Aft-swept wing settings are used in high subsonic and supersonic flight.[67] The wings of the B-1B originally were cleared for use at settings of 15, 25, 55 and 67.5 degrees. The 45-degree setting was later cleared in 1998–99 timeframe.[citation needed]
The B-1's variable-sweep wings and thrust-to-weight ratio provide it with better takeoff performance, allowing it to use more runways than previous bombers.[68] The length of the aircraft presented a flexing problem due to air turbulence at low altitude. To alleviate this, Rockwell included small triangular fin control surfaces or vanes near the nose on the B-1. The B-1's Structural Mode Control System rotates the vanes automatically to counteract turbulence and smooth out the ride.[69]

Engines and intakes

A rear view of a B-1B at Royal International Air Tattoo air show in 2004
Rear view of B-1B in flight, 2004
Unlike the B-1A, the B-1B cannot reach Mach 2+ speeds; its maximum speed is Mach 1.25 (about 950 mph or 1,530 km/h at altitude),[70] but its low-level speed increased to Mach 0.92 (700 mph, 1,130 km/h).[60] The speed of the current version of the aircraft is limited by the need to avoid damage to its structure and air intakes. To help lower its radar cross section (RCS), the B-1B uses serpentine air intake ducts and fixed intake ramps, which limit its speed compared to the B-1A. Vanes in the intake ducts serve to deflect and shield radar emissions from the highly reflective engine compressor blades.[71]
The B-1A's engine was modified slightly to produce the GE F101-102 for the B-1B, with an emphasis on durability, and increased efficiency.[72] The core of this engine has since been re-used in several other engine designs, including the GE F110 which has seen use in the F-14 Tomcat, F-15K/SG variants and most recent versions of the General Dynamics F-16 Fighting Falcon.[73] It is also the basis for the non-afterburning GE F118 used in the B-2 Spirit and the U-2S.[73] The F101 engine was the basis for the core of the extremely popular CFM56 civil engine, which can be found on some versions of practically every small-to-medium sized airliner.[74] The nose gear cover door has controls for the auxiliary power units (APUs), which allow for quick starts of the APUs upon order to scramble.[75][76]

Avionics

The B-1's main computer is the IBM AP-101, which is also used on the Space Shuttle orbiter and the B-52 bomber.[77] The computer is programmed with the JOVIAL programming language.[78] The Lancer's offensive avionics include the Westinghouse (now Northrop Grumman) AN/APQ-164 forward-looking offensive passive electronically scanned array radar set with electronic beam steering (and a fixed antenna pointed downward for reduced radar observability), synthetic aperture radar, ground moving target indicator (GMTI), and terrain-following radar modes, Doppler navigation, radar altimeter, and an inertial navigation suite.[79] The B-1B Block D upgrade added a Global Positioning System (GPS) receiver beginning in 1995.[80]
The interior of a B-1B cockpit at night
B-1B cockpit at night
The B-1's defensive electronics include the Eaton AN/ALQ-161A radar warning and defensive jamming equipment,[81] which has three sets of antennas; one at the front base of each wing and the third rear-facing in the tail radome.[82][83] The ALQ-161 is linked to a total of eight AN/ALE-49 flare dispensers located on top behind the canopy, which are handled by the AN/ASQ-184 avionics management system.[84] Each AN/ALE-49 dispenser has a capacity of 12 MJU-23A/B flares. The MJU-23A/B flare is one of the world's largest infrared countermeasure flares at a weight of over 3.3 pounds (1.5 kg).[85] The B-1 has also been equipped to carry the ALE-50 Towed Decoy System.[86]
Also aiding the B-1's survivability is its relatively low radar cross-section (RCS). Although not technically a stealth aircraft in a comprehensive sense, thanks to the aircraft's structure, serpentine intake paths and use of radar-absorbent material its RCS is about 1/50th that of the B-52 (probably about 26 ft² or 2.4 m²), although the Lancer is not substantially smaller in mass than the Stratofortress.[84][87]

Upgrades

A B-1B makes a high-speed, transonic pass, with the aircraft passing through a shock wave during the Pensacola Beach air show in 2003
A B-1B makes a high-speed, transonic pass at the Pensacola Beach air show, 2003
The B-1 has been upgraded since production, beginning with the "Conventional Mission Upgrade Program" (CMUP) This program added a new MIL-STD-1760 smart-weapons interface to enable the use of precision-guided conventional weapons. CMUP began with Block A, which was the standard B-1B with the capability to deliver non-precision gravity bombs. Block B brought an improved Synthetic Aperture Radar, and some upgrades to the Defensive Countermeasures System and was fielded in 1995. Block C provided an "enhanced capability" for delivery of up to 30 cluster bomb units (CBUs) per sortie with modifications made to 50 bomb racks.[88]
Block D added a "Near Precision Capability" for B-1 aircrews to accurately put bombs on target with improved weapons and targeting systems, and added advanced secure communications capabilities.[88] The first part of the electronic countermeasures upgrade added Joint Direct Attack Munitions (JDAM), ALE-50 Towed Decoy System, and anti-jam radios.[81][89][90] Block E upgraded the avionics computers and incorporated the Wind Corrected Munitions Dispenser (WCMD), the AGM-154 Joint Standoff Weapon (JSOW) and the AGM-158 JASSM (Joint Air to Surface Standoff Munition), substantially improving the bomber's capability. Upgrades were completed in September 2006.[91] Block F was the Defensive Systems Upgrade Program (DSUP) to improve the aircraft's electronic countermeasures and jamming capabilities, but it was canceled in December 2002 due to cost overruns and schedule slips.[92]
The Sniper XR targeting pod is being integrated on the B-1 fleet. The pod is mounted on an external hardpoint at the aircraft's chin near the forward bomb bay.[93] Following accelerated testing, the Sniper pod was fielded in summer 2008.[94][95] Future precision munitions include the GBU-39 Small Diameter Bomb.[96] In 2011, the Air Force was considering upgrading the B-1s with multiple ejector racks so that they can carry three times as many smaller JDAMs than they currently can.[97]
Sideview of a B-1B's nose section, which features a Sniper XR pod mounted on its chin
Nose of B-1 with the Sniper XR pod hanging below
Subsequent upgrades will provide for better network-centric capability. A program was begun in 2005 to provide integrated data linking and upgraded crew station displays.[98] A B-1 equipped with the Fully Integrated Data Link (FIDL) first flew on 29 July 2009. The FIDL allows for electronic data sharing so the crew will no longer have to enter information between systems by hand.[99] In July 2011, Boeing announced the Integrated Battle Station (IBS) program to modify the B-1B fleet. Upgrades include the integration of new display units in the cockpit, and a Central Integrated Test System; these are to improve situational awareness. Two monochrome displays are replaced by four multi-function color displays; the aging Aircraft Performance Monitoring Computer is replaced by an upgraded unit.[100] In June 2012, the B-1Bs are receiving Sustainment-Block 16 upgrades to add color displays, Link 16 networking, and digital flight instrument displays.[101] Developmental testing will start in April 2013.[102]


Variants

The rear section showing the B-1A's pointed radome
B-1A
The B-1A was the original B-1 design with variable engine intakes and Mach 2.2 top speed. Four prototypes were built; no production units were manufactured.[120][134]
B-1B
The B-1B is a revised B-1 design with reduced radar signature and a top speed of Mach 1.25. It was otherwise optimized for low-level penetration. A total of 100 B-1Bs were produced.[134]
B-1R
The B-1R is a proposed upgrade of existing B-1B aircraft.[135] The B-1R (R for "regional") would be fitted with advanced radars, air-to-air missiles, and new Pratt & Whitney F119 engines. This variant would have a top speed of Mach 2.2, but with 20% less range.[136]
Existing external hardpoints would be modified to allow multiple conventional weapons to be carried, increasing overall loadout. For air-to-air defense, an Active Electronically Scanned Array (AESA) radar would be added and some existing hardpoints modified to carry air-to-air missiles. If needed the B-1R could escape from unfavorable air-to-air encounters with its Mach 2+ speed. Few aircraft are currently capable of sustained speeds over Mach 2



General characteristics
  • Crew: 4 (aircraft commander, copilot, offensive systems officer and defensive systems officer)
  • Payload: 125,000 lb (56,700 kg) ; internal and external ordnance combined
  • Length: 146 ft (44.5 m)
  • Wingspan:
    • Extended: 137 ft (41.8 m)
    • Swept: 79 ft (24 m))
  • Height: 34 ft (10.4 m)
  • Wing area: 1,950 ft² (181.2 m²)
  • Airfoil: NA69-190-2
  • Empty weight: 192,000 lb (87,100 kg)
  • Loaded weight: 326,000 lb (148,000 kg)
  • Max. takeoff weight: 477,000 lb (216,400 kg)
  • Powerplant: 4 × General Electric F101-GE-102 augmented turbofans
    • Dry thrust: 14,600 lbf (64.9 kN) each
    • Thrust with afterburner: 30,780 lbf (136.92 kN) each
  • Fuel capacity, optional: 10,000 U.S. gal (38,000 L) fuel tank for 1–3 internal weapons bays each
Performance
  • Maximum speed:
    • At altitude: Mach 1.25 (721 knots, 830 mph, 1,340 km/h at 50,000 ft/15,000 m altitude)
    • At low level: Mach 0.92 (700 mph (1,100 km/h) at 200–500 ft (61–150 m) altitude)
  • Range: 6,478 nmi (7,456 mi (11,999 km))
  • Combat radius: 2,993 nmi (3,445 mi (5,544 km))
  • Service ceiling: 60,000 ft (18,000 m)
  • Wing loading: 167 lb/ft² (816 kg/m²)
  • Thrust/weight: 0.38
Armament
Avionics

 From Wikipedia

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