v1.0.1 / 01 jul 04 / greg goebel / public domain
* The heavy bomber seemed like it was headed for extinction in the 1960s, with development projects cancelled in favor of long-range strategic missiles. However, the US Air Force still felt a need for the type, and in the 1970s and 1980s pushed the development of a new heavy bomber, the Rockwell "B-1", which is now a prominent tool of American power. This document provides a history and description of the B-1.
* In the late 1950s, the US Air Force planned to obtain large numbers of a Mach 3 bomber, the North American "B-70 Valkyrie", as the backbone of their strategic nuclear bombing force. However, improvements in Soviet air defenses and the development of the US long-range ballistic missile force rendered a high-altitude bomber like the B-70 obsolete. Only two "XB-70s" were completed, as high-speed research aircraft.
The Air Force still remained interested in a new manned bomber, and in fact no sooner had the B-70 been given the axe than the USAF began to consider another new bomber. The result was an "alphabet soup" of studies beginning with the "Subsonic Low Altitude Bomber (SLAB)" in 1961; the "Extended Range Strike Aircraft (ERSA)" in 1963; the "Advanced Manned Precision Strike System (AMPSS)" in 1964; and finally the "Advanced Manned Strategic Aircraft (AMSA)" in 1965:1969. Some jokers suggested that "AMSA" actually stood for "America's Most Studied Aircraft".
AMSA led to a request for proposals by the Air Force in November 1969. After due consideration of proposals from Boeing, General Dynamics, and North American Rockwell, the USAF awarded the contract for the "B-1" bomber to Rockwell on 5 June 1970, while General Electric was awarded a contract on the same day for the F101 afterburning turbofan engine that would power the aircraft.
The USAF originally wanted to build two ground-test airframes and five flying prototypes, but the requirement was cut in 1971 to one ground-test airframe and three flying prototypes. A fourth flying prototype would be ordered in 1976. The Air Force wanted 240 production machines, with the last of them to be delivered in 1979.
The initial flight of the first B-1 prototype was on 23 December 1974, followed by the first flight of the third prototype on 26 March 1976; The second prototype had been reserved for ground tests and didn't fly until 14 June 1976. The fourth prototype performed its initial flight on 14 February 1979. The fourth prototype featured, at least for part of its life, a distinctive dorsal spine housing test electronics. The spine was not fitted to any other B-1.
By the time of the first flight of the fourth prototype, however, the B-1 seemed all but dead. The 1970s saw a push for disarmament, and production of the B-1 was cancelled by US President Jimmy Carter on 30 June 1977. The price of the B-1 had been creeping upward, and Carter believed that cruise missiles would be a cheaper nuclear deterrent. The four B-1 prototypes were to remain in flight test as a form of "insurance". The Air Force went on to conduct another series of studies. Rockwell proposed a cost-reduced version of the B-1 that had fixed wings and could be used as a nuclear or conventional bomber, or a tanker. The Air Force didn't bite on that proposal, but was interested in an improved B-1 known as the "Long Range Combat Aircraft (LRCA)".
A resurgence of tensions with the Soviets and other factors led to the election of Ronald Reagan as US president in 1980. Reagan was committed to a major arms buildup, and this led to the resurrection of the B-1 LRCA as the "B-1B", which was promoted as a cruise-missile carrier though it still retained its free-fall nuclear bombing capability. The original B-1 prototypes were retroactively given the designation "B-1A". Reagan announced the decision to go ahead with the B-1B in October 1981, and formal contracts for a hundred production machines were finalized on 20 January 1982.
The second and fourth B-1A prototypes were to be used for B-1B development, with the fourth built up as the B-1B pre-production prototype. The second prototype was lost in a crash on 29 August 1984, killing the pilot, Rockwell chief test pilot Doug Benefield, and badly injuring the rest of the crew.
Despite the accident, the program went forward. The first production machine performed its initial flight on 18 October 1984, with initial service delivery on 29 June 1985. The last of the hundred was delivered by the end of the decade, with five bomb wings operating the type. Although formally named the "Lancer", the B-1B is more generally known as the "Bone", from "B-One".
* The B-1B is a sleek, dartlike aircraft with a variable geometry "swing wing", which can be extended to full span for takeoff, landing, and long-range cruise, and swept back for high-speed penetration of adversary airspace. The swing wing does impose a weight penalty, but when extended it increases range and allows the B-1B to use shorter airstrips, assisting in dispersal of forces or forward-basing in time of war, while giving the bomber a good solid low-level ride in sweptback position.
Minimum sweep is 15 degrees and maximum sweep is 67.5 degrees. The junction where the wing sweeps into the wing glove features a "seal" to ensure aerodynamic cleanliness. The sealing system was derived from that developed for the European swing-wing Panavia Tornado strike fighter / interceptor, and features an inflatable bag covered with "fingers".
The wing has lift-enhancement devices for relatively short takeoffs with a full load, including seven-segment full-span leading-edge slats and six-segment trailing-edge Fowler-type flaps. There are no ailerons, with four spoilers on the top of each wing to provide lateral control and for use as airbrakes.
The tail is of conventional configuration, with an all-moving horizontal tailplane and a single tailfin. The rudder has three sections, and the tailplanes can move in opposite directions to help with lateral control. They are also turned to their maximum nose-down position to act as an airbrake on landings.
There are small moveable vanes made of composites alongside the nose, with an anhedral of 30 degrees, referred to in an absolutely opaque way as the "structural mode control system (SMCS)" foreplanes. They were fitted because the long B-1B fuselage tends to flex fore-and-aft in low level flight. The SMCS vanes are linked to a set of accelerometers near the center and nose of the bomber under computer control to ensure a smooth ride at low level, increasing crew comfort and airframe life.
There are eight self-sealing fuel tanks, filling up much of the fuselage and parts of the wing assembly. Additional fuel tanks can be installed in the weapons bays. All fuel tanks are pressurized with inert nitrogen to reduce fuel explosion hazard. Incidentally, the B-1B's "Fuel & Center Of Gravity Management Subsystem (FCGMS)" shifts fuel from one tank to another to maintain trim when the aircraft changes the sweep of its wings.
There is a midair refueling socket in the nose, just forward of the windshield. The position of the socket allows the bomber's flight crew to keep an eye on a tanker's refueling boom. The top of the nose is painted with a white "fishbone" pattern to help the tanker boom operator find the bomber's refueling socket at night.
The B-1B is made mostly of aluminum alloys and titanium, with a few composite elements. The central "box" that supports the swing wings is made of titanium. The aircraft is structurally reinforced to withstand the shock of a nuclear blast. The fuselage has smooth contours, with wing-body blending, and uses radar absorbing material (RAM) to give it a radar cross section only about one or two percent of that of the B-52, despite the fact that the two aircraft are roughly the same size. While the original prototype B-1As flew in a natty white anti-nuclear flash or a multitone camouflage paint scheme, operational B-1Bs have been given dark color schemes, eventually standardizing on an overall "gunship gray" paint job.
The B-1B is powered by four F101-GE-102 afterburning turbofans with 75.6 kN (7,710 kg / 17,000 lb) dry thrust and 136.9 kN (13,960 kg / 30,780 lb) afterburning thrust each. The B-1B can fly on only two engines if necessary, and can even stay in the air on one if much of the fuel is dumped.
The engines are organized into two pods with two engines each, mounted under the rear of the wing root gloves. Engine bleed is distributed throughout the aircraft for cabin pressurization and a range of other purposes. There is an auxiliary power unit (APU) mounted between the engines in each pod, primarily to start the engines. though they can be used for ground power. The APUs allow a quick startup of the engines so the bomber can get off the runway in a hurry. There's a switch on the nosewheel gear that a crewman can use to get the APUs and engines going even as the crew is getting into the bomber. A single APU can be used to fire up all four engines.
The engines have fixed inlets, instead of the variable inlets of the B-1A. The B-1A had been designed to perform high-altitude penetration at dash speeds in excess of Mach 2, but this was unrealistic even at the time, and though the B-1B's fixed inlets cut the high-altitude dash speed to Mach 1.25, they raised its low-level speed from the B-1A's Mach 0.85 to Mach 0.92. The B-1B's inlets are also designed to shield the engine fans from radar to improve stealth. The inlets feature a deicing system.
One of the interesting minor details of the B-1B is that the Bone was originally delivered with "turkey feathers" shroud around the variable engine exhaust. The shroud was removed in the 1990s as a weight and maintenance reduction measure, leaving the variable exhaust actuators exposed.
The B-1B has tricycle landing gear, with twin-wheel nose gear and main gear
with four-wheel 2-by-2 bogeys. The steerable nose gear retracts forward,
while the main gear retracts into the center of the aircraft. The landing
gear was reinforced from the B-1A to handle greater takeoff weights. Carbon
brakes are fitted to help reduce landing roll.
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spec metric english
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wingspan, extended 41.67 meters 136 feet 8 inches
wingspan, swept 23.84 meters 78 feet 2 inches
length 44.81 meters 147 feet
height 10.36 meters 34 feet
empty weight 87,090 kilograms 192,000 pounds
MTO weight 216,365 kilograms 477,000 pounds
max speed 1,330 KPH 825 MPH / 720 KT
penetration speed 965 KPH 600 MPH / 520 KT
service ceiling > 15,250 meters > 50,000 feet
unrefueled range 12,000 KM 7,455 MI / 6,485 NMI
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Penetration speed is given at 60 meters (200 feet).
The B-1B was originally tasked for delivery of free-fall nuclear weapons. with each bay carrying a single "Multi-Purpose Launcher (MPL)" with a capacity of eight nukes. The destructive capability of a single B-1B loaded up with 24 nuclear weapons is beyond comprehension.
The bomber could carry up to 24 Short Range Attack Missiles (SRAMs), but SRAM was obsoleted in 1990, and although the B-1B was partly promoted as a cruise missile carrier, arms limitation treaties ensured that it has never carried such weapons operationally. As a result, the partition between the front two weapons bays has never been moved or removed operationally, and Russian arms-treaty inspectors check to see that it stays where it is.
As discussed in the next section, there was some delay in qualifying the B-1B for conventional munitions. In principle, the B-1B can also be fitted with up to eight underfuselage hardpoints that can carry up to 26,760 kilograms (59,000 pounds) of munitions. In practice, it's never been done operationally, again because of arms-limitation treaties.
* The Bone carries a crew of four, including pilot, copilot, "Defensive Systems Operator (DSO)", and "Offensive Systems Operator (OSO)". The pilot sits on the left in the forward compartment, with the copilot on the right. The DSO sits on the left in the rear compartment, with the OSO on the right. The two compartments are connected by a a tunnel, which can be used as a sleep station on long missions. Although the B-1A had no windows in the rear compartment, test crews claimed that this made the place feel claustrophobic, and so the B-1B has a small window on each side of the rear compartment.
The crew enters the bomber through a hatch behind the nosewheel bay that opens into the rear compartment. Crew accommodations are much more comfortable than those of the B-52, and the cockpit is regarded as very well laid out, with a clean dashboard arrangement and fighter-style stick controls for pilot and copilot. The B-1B is said to handle very nicely for an aircraft of its size, with one USAF test pilot commenting: "Sometimes you've got to stop and think how big this aircraft is before you do some things because it handles so well."
A toilet and galley are provided to support long missions, and there is space for two instructors along with the crew of four. However, the instructors sit on fixed seats, meaning that they have to bail out manually in case of an emergency. After the deaths of two instructors in a crash in 1987, USAF procedures were changed so that only four crew are taken on low-level training missions.
The large, sloping windshield has an electrical demisting and deicing system, and is reinforced against birdstrikes, a big threat in low-level flight. All windows can be covered with nuclear flash shields with zirconium titanate ports. While the first three B-1As featured a crew escape capsule, whose malfunction led to the fatal results in the loss of the second B-1A prototype, it was judged unstable at high speeds, and so the fourth B-1A and the B-1Bs use individual upward-ejecting Weber ACES II ejection seats.
* The B-1B's avionics suite is more sophisticated than that of the B-1A. The "Offensive Avionics System (OAS)" used by the OSO was integrated by Boeing. One of the main elements is the Westinghouse AN/APQ-164 multimode offensive radar system, derived from the AN/APG-66 radar used on the F-16 fighter. The AN/APQ-164 features a phased array antenna, mounted in the nose of the bomber; and "low probability of intercept" operation, including the capability to take single "snapshot" sweeps, or partial sweeps. The radar has eleven modes, including terrain-following; navigation; tanker rendezvous; and targeting with a "synthetic aperture radar (SAR)" imaging capability.
The B-1B's original navigation systems include a precision inertial navigation system (INS), TACAN and ILS, and a Honeywell AN/ASN-121 radar altimeter. Honeywell also provided the offensive and defensive system displays, which includes three color multifunction displays (MFDs). Two of the displays are used by the OSO, while one is used by the DSO.
The DSO relies mainly on the Eaton "Defensive Countermeasures System (DAS)", which includes an AN/ALQ-161 receiver / jammer set; a tail warning radar; and an AN/ASQ-184 defensive management system, which can automatically control jamming functions and dispersal of chaff or flares from the "expendable countermeasures (EXCM)" system. There are eight dispensers arranged over the B-1B, with each dispenser having a capacity of twelve flares or 120 chaff cartridges. Current doctrine involves crosstraining the DSO and OSO to do each other's job if need be.
The B-1B also carries an extensive communications suite, including an Air Force Satellite Communications (AFSATCOM) link. There are a number of blade antennas for the communications and defensive that slightly disfigure the Bone's elegant contours. Most of the electronic systems are linked by quadruple-redundant MIL-STD 1553 data buses, and all are "hardened" to allow them to operate through the electromagnetic pulse (EMP) accompanying a nuclear blast, or other sources of electronic interference.
Other features of the B-1B include a "central integrated test system (CITS)" to help maintain the bomber; an "on-board oxygen generating system (OBOGS)" to eliminate the need to stock oxygen bottles; and a redundant hydraulic system.
* The B-1B initially proved very controversial in service. There were a number of losses from accidents, along with high-profile groundings due to such problems as fuel leaks. The DAS system was particularly troublesome, demanding a series of expensive upgrades. Even after the worst problems were worked out, the bomber's availability rate was low, and ground crews admitted that the big, complicated machine was maintenance-intensive. The Air Force defended the program, pointing out that even the good old dependable B-52 had suffered its share of teething problems in its early days, and that inadequate funding for B-1 spares was a big part of the availability problem. However, the criticisms continued.
As if to add to the USAF's embarrassment, the B-1B did not see combat service during the Gulf War in 1991, the B-52 performing all the heavy bomber strikes, despite the fact that the B-1B had a conventional attack capability.
The bomber had been qualified early on to carry Mark 80 series "iron" bombs and comparable mines. The smaller Mark 82 225 kilogram (500 pound) bombs, and the Mark 62 mines based on the Mark 82, are carried in what amounts to a "clip", known as a "Conventional Bomb Module (CBM)". Each CBM can store 28 munitions and one CBM can be loaded into each weapons bay, for a total warload of 84 munitions.
The big 900 kilogram (2,000 pound) Mark 84 bombs, and the comparable Mark 65 mines, are carried on a "Conventional Rotary Launcher (CRL)". Each CRL can carry 8 munitions, for a total warload of 24 munitions. More munitions could be carried on the external hardpoints, but as noted they've never been fitted in practice.
Incidentally, reloading munitions into a Bone is, or at least was, a troublesome procedure. According to the story, since the B-1 was originally designed for the strategic nuclear strike role, not a lot of thought was given to the reloading issue. The assumption was that after the first wave of strikes, the B-1B would have nowhere left to go to reload. This seems a little short-sighted and may be a rumor.
* In any case, the reason that the B-1B didn't go into action in the Gulf War was primarily because the USAF reserved the aircraft for nuclear strike, where its superior ability to penetrate enemy airspace made it preferable to the B-52. The B-1B's conventional strike capability was rudimentary, and that mission was better performed by other platforms.
Unfortunately, this policy led to more criticism from the US Congress. There was some justification for the criticism, since the fall of the USSR meant that the Air Force needed to deemphasize the deterrent role and focus more heavily on fighting the seemingly endless "little wars" that followed the end of the Cold War.
As a result, the USAF focused on improving the Bone's conventional strike capability, beginning the B-1B "Conventional Munitions Upgrade Program (CMUP)" in 1993. CMUP has been implemented as a series of "block" upgrades. "Block A" was defined as the pre-CMUP B-1B, with following blocks defined as follows:
Other elements of the upgrade included a MIL-STD 1760 "smart weapons" interface for downloading target coordinates into the bombs; a GPS navigation system; improved radios; and support for the AN/ALE-40 towed decoy, which produces a big radar signature to baffle radar-guided missiles. Block D was initiated in 1995 and was completed in 2003.
Incidentally, the B-1B has test-dropped laser-guided bombs (LGBs) and can in principle carry them, providing a high-precision strike capability. However, the Bone doesn't carry a laser target designator, and use of LGBs would imply using a target designator provided by another aircraft or by ground forces. There is little evidence that the B-1B has ever carried LGBs on operational missions.
Block E will be able to carry a mixed load of these weapons, and launch them all simultaneously. The Block E upgrade program was initiated in 1995, and at last notice was scheduled to be completed in 2005.
* In 1995, to demonstrate that the B-1B was finally coming of age as a first-line aircraft, the Air Force conducted a round-the-world flight with two Bones that broke records. The two bombers made simulated attacks on ranges in Italy, the western Pacific, and the US state of Utah.
The B-1B finally went into combat in December 1998, as part of the four-day series of attacks on Iraq designated OPERATION DESERT FOX, performing six sorties and dropping iron bombs. It went back into action just a few months later in the spring of 1999, as part of the NATO air offensive against Serbian aggression in Kosovo, codenamed OPERATION ALLIED FORCE. The B-1B performed over a hundred sorties, also dropping iron bombs. Cluster bomb canisters were carried but not actually used in action.
The B-1 performed excellent service during OPERATION ENDURING FREEDOM, the Afghanistan campaign in 2001:2002, often operating in an unusual "close support" role. The bombers would fly out of the island of Diego Garcia in the Indian Ocean loaded with JDAMs, then orbit the battle theater, waiting to be informed of a target. The flight crews would receive targeting information over a data link, load it into bombs and set fuzing options, and then proceed to the target area to drop the bombs. They would then return to orbit and wait for a new target. Although there was no real opposition in the air to US forces, one B-1 was lost in early December 2001, due to an engine fire that occurred shortly after takeoff. The four crew members ejected and were recovered safely.
The B-1 was heavily involved in OPERATION IRAQI FREEDOM, the invasion of Iraq in the spring of 2003. Although B-1s only flew 2% of the sorties, they dropped 2,100 JDAMs, or half the total expended. Each B-1 carried 24 900 kilogram (2,000 pound) JDAMs, usually split between penetrators with short delay fuzes and contact detonated bombs. About a dozen B-1Bs were flown from Oman in support of the operation. They were used in "quick reaction" strikes in attempts to kill Iraqi leadership.
* The Air Force wants to implement further improvements to their B-1Bs to keep them effective:
* While bombers like the B-52, B-1, and B-2 have proven to be highly valuable assets in the widespread small wars that followed the collapse of the Soviet Union, these conflicts have not required great fleets of such aircraft. In 2002, the Air Force decided to withdraw 33 of the 91 B-1Bs surviving in service. Eight of the 33 were used as static display pieces, with the other 24 sent to the "boneyard" at Davis-Montham AFB in Arizona. Ten of the 24 were mothballed, while the other 14 will be cannibalized for spares.
The number of B-1B bases was reduced from five to two, including Ellsworth AFB in South Dakota and Dyess AFB in Texas. There were some observers who suspected that the drawdown in B-1B stocks was just a prelude to phasing the machine out completely. It would be deeply ironic for the B-1B to be retired while the B-52H remains in service, but that remains to be seen.
In 2004 the Air Force requested that the aircraft industry submit proposals for a long-range strike platform, for development beginning in 2008, leading to an initial operational capability in 2015 and full operational capability in 2020. Boeing submitted a proposal for a "B-1R", where "R" stood for "Regional", which would be fitted with the Pratt & Whitney F-119 engine used on the F/A-22. Four F-119s would give the B-1R a top speed of over Mach 2 and an operational radius of 4,800 kilometers (3,000 miles). It would feature improved stealth features and countermeasures, state-of-the-art radar, AIM-120 AMRAAM missiles for self-defense, and a new light air-to-surface standoff missile.
The Air Force was simply investigating options, and Boeing provided a set of other concepts, such as a long-range robot bomber, a ballistic missile with a maneuvering reentry vehicle, and long-range cruise missiles. Air Force officials have also given some thought to using the B-1B to carry new high-powered attack lasers now in development, but this is a purely speculative concept at this time.
* The first time I saw a B-1 was the most memorable, if the most fleeting. I was on the way south across the barrens of Wyoming, a land of great empty spaces where USAF bombers like to prowl, and driving up a hill. At the top of the hill, the road met the sky, flanked by tall banks on either side.
As I started up the hill, a slender black dart zipped from one bank to the other. I floored the gas pedal to get to the top of the hill as fast as I could, but I knew it was pointless. By the time I reached the top amd looked out over the badlands, the machine was long gone over the horizon. I only saw the thing for a flash but I had no doubt of what it was.
* Sources include:
* Revision history:
v1.0.0 / 01 feb 03 / gvg
v1.0.1 / 01 jul 04 / gvg / Minor tweak update.