United States of America (1974)
Prototype Supersonic Heavy Bomber – 4 Built
The B-1A program arose out of a need for a long-range, supersonic, low-flying heavy bomber. The program’s initial development was pushed forward through an ever-shifting geopolitical landscape, as well as opposition and contention among the the top levels of the U.S. government. Even with advanced features such as variable sweep wings, and variable air intake and exhaust capability, it was derided as a ‘dinosaur’ in the age of ICBMs. The opposition and political infighting nearly ended the Lancer, before it was given a miraculous second chance.
The origin of the Rockwell B-1 can be traced back to 1961, when the Air Force began to consider alternatives to the North American B-70 Valkyrie, which had just been downgraded from production to test aircraft status. At that time, the long range strategic missile was assumed to be the weapon of the future, with manned long-range bombers being relegated to a secondary role. The B-70 had been designed to fly at extremely high altitudes and at Mach 3 speeds, and increasingly effective Soviet anti aircraft defenses had made such an aircraft rather vulnerable.
Nevertheless, the Air Force commissioned several studies to explore possible roles for manned bombers in future planning. If successful, these would replace the B-52. At this time, the ability to fly through enemy airspace at extremely low altitudes was was thought to be the key for survival in the face of sophisticated air defenses.
The first such study was known as the Subsonic Low Altitude Bomber (SLAB), which was completed in 1961. It envisaged a 500,000 pound fixed-wing aircraft with a total range of 11,000 nautical miles, with 4300 nm of these miles being flown at low altitudes. This was followed soon after by the Extended Range Strike Aircraft (ERSA), which had a weight of 600,000 pounds and featured a variable sweep wing. The ERSA was supposed to be able to carry a payload of 10,000 pounds and achieve a range of 8750 nautical miles, with 2500 of these miles being flown at altitudes as low as 500 feet. In August of 1963, a third study known as Low-Altitude Manned Penetrator(LAMP) was completed. It called for a 20,000 payload and a 6200 nautical mile range, 2000 miles being flown at low altitude. None of these projects ever got beyond the basic concept stage.
In October of 1963, the Air Force looked over these proposals and used the results as the foundation of a new bomber proposal, termed Advanced Manned Precision Strike System (AMPSS). In November of that year, 3 contractors were issued Requests for Proposals for the AMPSS. The companies were Boeing, General Dynamics, and North American. However, Secretary of Defense Robert McNamara kept a tight rein on funds, and expressed doubts about the assumptions behind AMPSS, so the RFPs only involved basic concept studies and did not focus on a specific aircraft. In addition, the contractors all agreed that some of the suggested USAF requirements either did not make much sense or else were prohibitively costly.
In mid-1964, the USAF had revised its requirements and retitled the project as Advanced Manned Strategic Aircraft (AMSA). The AMSA still envisaged an aircraft with the takeoff and low-altitude performance characteristics of the AMPSS, but in addition asked for a high-altitude supersonic performance capability. The projected gross weight for the aircraft was 375,000 pounds, and the range was to be 6300 nautical miles, 2000 of which would be flown at low altitude.
Secretary McNamara was never very excited about the AMSA, since he thought that strategic missiles could do a better job of “assured destruction” than manned bombers, and thought that the cost of the AMSA would probably be excessive. Nevertheless, there was a potential gain in avionics and propulsion technology that could be achieved if the project were to proceed, and McNamara released a small amount of funding for preliminary AMSA studies. The airframe for the AMSA would be worked on by Boeing, General Dynamics, and North American, whereas Curtiss-Wright, General Electric, and Pratt & Whitney would work on the engines. Both IBM and Hughes aircraft looked at potential avionics systems. These contractors issued their reports in late 1964. General Electric and Pratt & Whitney were given a contract to produce two demonstrator engines, but no airframe and avionics contracts were issued at that time.
A bit of confusion entered the picture when the Defense Department selected the FB-111A as the replacement for the B-52C, B-52F, and B-58. The Air Force had not requested a bomber version of the controversial F-111, and was not all that enthusiastic about the choice. Nevertheless, a low-cost interim bomber did have some attractive features, and the Air Force went along with the choice of the FB-111A provided it did not interfere with AMSA development.
By 1968, an advanced development contract was issued to IBM and the Autonetics Division of North American Rockwell. On September 22, 1967, North American Aviation had merged with Rockwell Standard Corporation to create North American Rockwell. Earlier in that year, the Joint Chiefs of Staff had recommended the immediate development of the AMSA, but Secretary McNamara was still opposed, preferring instead to upgrade the existing FB-111 and B-52 fleet. McNamara vetoed the proposal.
When Richard Nixon became President in January of 1969, his Secretary of Defense Melvin Laird reviewed Defense Department needs and announced in March of 1969 that the planned acquisition of 253 FB-111s would be reduced to only 76, since the FB-111 lacked the range and payload required for strategic operations, and recommended that the AMSA design studies be accelerated.
The AMSA was officially assigned the designation B-1A in April of 1969. This was the first entry in the new bomber designation series, first created in 1962.
New Requests For Proposals were issued in November of 1969. IBM and Autonetics were selected for the avionics work on December 19. The selection of airframe and engine contractors was delayed by budget cuts in FY 1970 and 1971. On December 8, 1969 North American Rockwell and General Electric were announced as the winners of the respective airframe and engine contracts for the B-1A.
The original program called for 2 test airframes, 5 flyable aircraft, and 40 engines. This was cut in 1971 to one ground test aircraft and 3 flight test articles (74-0158/0160). First flight was set for April of 1974. A fourth prototype (76-1074) was ordered in the FY 1976 budget. This fourth plane was to be built to production standards. At one time, some 240 B-1As were to be built, with initial operational capability set for 1979.
The fuselage of the B-1A was fairly slim, and seated a crew of four in the nose. There was a large swept vertical tail, with a set of all-flying slab tailplanes mounted fairly high on the vertical tail. The aircraft’s fuselage blended smoothly into the wing to enhance lift and reduce drag. In addition, the fuselage was designed to reduce the aircraft’s radar cross section in order to minimize the probability of detection by enemy defenses.
In order to achieve the required high-speed performance and still be able to have a good low-speed takeoff and landing capability, a variable-sweep wing was used. This made it possible for the aircraft to use short runways that would be inaccessible to the B-52. The outer wing panels were attached to a wing carry-through attachment box which faired smoothly into a slim, narrow fuselage. Each outer wing had full-span slats and slotted flaps, but used no ailerons. Lateral control was provided by a set of spoilers on the wing upper surface, acting in conjunction with differential operation of the slab tailplanes.
The engines were four afterburning General Electric F101-100 turbofans. The engines were installed in pairs inside large nacelles underneath the wing roots,, and close to the aircraft’s center of gravity to improve stability while flying at high speed through highly-turbulent low-altitude air. The nacelles were far enough apart so that the main landing gear members could be installed in the wing roots between them with enough clearance to retract inwards. In order to achieve the required Mach 2 performance at high altitudes, the air intake inlets were variable. In addition, the exhaust nozzles were fully variable.
Initially, it had been expected that a Mach 1.2 performance could be achieved at low altitude, which required that titanium rather than aluminum be used in critical areas in the fuselage and wing structure. However, this low altitude performance requirement was lowered to only Mach 0.85, enabling a greater percentage of aluminum to be used, lowering the overall cost. Titanium was used primarily for the wing carry-through box, the inner ends of the outer wings incorporating the pivots, and for some areas around the engines and rear fuselage.
Eight integral fuel tanks were planned, one in each outer wing panel, and the rest in the fuselage. About 150,000 pounds of fuel could be carried. There were three 15-foot weapons bays in the lower fuselage, two ahead and one behind the wing carry-through box. Each bay could carry up to 25,000 pounds of conventional or nuclear weapons. The total weapons load was almost twice what a B-52 could carry. All of the offensive weapons were to be carried internally, with no provision for externally-mounted pylons. A key weapon was to be the AGM-69A SRAM (Short-Range Attack Missile), 8 of which could be carried on a rotary launcher in each of the weapons bays.
No defensive armament was planned, the B-1A relying on its low-altitude performance and its suite of electronic countermeasures gear to avoid interception.
An extensive suite of electronics was planned, including a Litton LN-15 inertial navigation system, a Doppler radar altimeter, a Hughes forward-looking infrared, and a General Electric APQ-114 forward-looking radar and a Texas Instruments APQ-146 terrain-following radar.
The B-1A carried a crew of four–a pilot, copilot, offensive systems officer, and defensive systems officer. The crew escape system resembled that of the F-111 crew escape module. In an emergency, a capsule containing all four crewmembers would separate from the aircraft and be steered and stabilized by various fins and spoilers. A rocket motor would fire and lift the capsule up and away from the aircraft. Three parachutes would then open and would lower the capsule along with the crew safely to the surface. Once down, the capsule would serve as a survival shelter for the crew members.
The B-1A mockup review occurred in late October of 1971. There were 297 requests for alterations.
The first B-1 flight aircraft (74-0158) rolled out from USAF Plant 42 at Palmdale, CA on October 26, 1974. It made its first flight on December 23, 1974, a short hop to Edwards AFB where the flight testing was to be carried out. The crew was Rockwell test pilot Charlie C. Bock,; Jr, Col. Emil Sturmthal, and Richard Abrams. The third aircraft (74-0160) was to be the avionics testbed and flew for the first time on March 26, 1976. The second aircraft (74-0159) was initially used for some static ground testing and did not make its first flight until June 14, 1976.
The B-1A test program went fairly smoothly. However, there were numerous modifications introduced throughout the program and some items of additional equipment were added. The avionics suite of the B-1A was perhaps the most complex yet used on an aircraft. The Initial Operational Test and Evaluation tests were successfully passed in September of 1976. The Phase 1 flight test program was completed on September 30, 1976. In December of 1976, the Air Force concluded that the B-1A was to go into production, with contracts placed for the first three aircraft and plans were made for an initial Block 2 production batch of 8 aircraft.
It seemed that the B-1A was well on its way to a full production run of 240 aircraft. However, the cost of the B-1A program began to escalate, and there were still some unresolved issues concerning the avionics suite. In 1970, the estimated per-unit price was $40 million, and by 1972, the cost had risen to $45.6 million. Although this sounds like small-change by today’s standards, this was considerably greater than the figure for any previous production aircraft. Moreover, by 1975, this number had climbed to $70 million.
Alarmed at these rising costs, the new presidential administration of Jimmy Carter (which had taken office on January 20, 1977) began to take a second look at the whole B-1A program. On June 30, 1977, President Carter announced that plans to produce the B-1A would be cancelled, and that the defense needs of the USA would be met by ICBMs, SLBMs, and a fleet of modernized B-52s armed with ALCMs. President Carter genuinely wanted to reduce the arms race, but he was unaware at the time of the secret projects that would ultimately lead to the F-117A stealth attack aircraft and the B-2 Spirit stealth bomber.
Despite the cancellation of the production program, the Carter administration allowed the flight testing of the B-1A to continue. Most of the effort involved the avionics, in particular the defensive systems. In addition, General Electric continued to work on improvements for the F101 engine, and most of the contractors kept their engineering teams intact. Perhaps most important, work continued in reducing the radar cross section of the aircraft. Less than a month after the cancellation, 74-0160 launched a SRAM on July 28, 1977 at an altitude of 6,000 feet over the White Sands missile range. This aircraft was later modified with an advanced electronic countermeasures system mounted in a dorsal spine, and Doppler beam sharpening was added to the forward-looking radar. 74-0158 had achieved Mach 2.0 in April of 1976, and after completing its stability and control tests was placed in storage in 1978. On October 5, 1978, 74-0159 achieved a speed of Mach 2.22, the highest speed achieved during the B-1A program.
74-0158 was retired from flying in April of 1981 after having flown 138 sorties, the largest number of flights of any of the prototypes. By this time, it had acquired a three-tone desert camouflage scheme. It was eventually dismantled and used as a weapons trainer at Lowry AFB.
74-0159 was later used as a flight test article in the B-1B program. It was modified by having B-1B flight control system features installed. It began flying on March 23, 1983. Unfortunately, it crashed on August 29, 1984 when the aircraft’s center of gravity got unbalanced during fuel transfer management procedures, causing it to lose control. The escape capsule deployed successfully, but the parachute risers did not deploy properly. The capsule hit the ground at a steep angle, so steep that the inflatable cushions could not shield the impact. Chief test pilot Doug Benefield was killed, and two other crew members were seriously injured.
74-0160 was later converted to a ground trainer under the designation GB-1A and is now on display at the Wings Over The Rockies Air and Space Museum (formerly Lowry AFB), near Denver, Colorado.
76-0174 had been ordered to serve as a pre-production B-1A aircraft and was configured with full avionics systems. When the B-1A program was cancelled, work on this aircraft was well under way. Unlike the first three B-1s, 76-0174 was equipped with four conventional ejector seats in place of the escape capsule. This change was made after tests had determined that the crew escape module was unstable if ejected at speeds above 347 knots. It flew on February 14, 1979 and carried out 70 sorties. This plane was later used as a test article in support of the B-1B program. It resumed flying on July 30, 1984. Externally, the main change was the removal of the long dorsal spine but many of the B-1B avionics systems were installed internally. It is now on display at the USAF Museum at Wright Patterson AFB in Ohio.
- B-1A – The initial prototype run of four aircraft
- U.S. Air Force – The sole operator of the B-1A was the USAF
(at max sweep)
|78 ft 2.5 in / 23.84 m|
(at min sweep)
|136 ft 8.5 in / 41.67 m|
|Length||143 ft 3.5 in / 43.8 m|
|Height||34 ft 0 in / 10.36 m|
|Wing Area||1,950 ft² / 181.2 m²|
|Engine||4x General Electric F101-GE-100 turbofans, 17,390 lbf dry, 30,000 lbf with afterburner|
|Fuel Capacity||29,755 US Gal / 11,2634 L|
|Loaded Weight||389,000 lb / 176,450 kg|
|Maximum Take Off Weight||395,000 lb / 179,170 kg|
|Maximum Speed||Mach 2.2 / 1,688 mph / 2716.5 kmh at 50,000 ft / 15,240 m|
|Maximum Service Ceiling||62,000 ft / 18,900 m|
|Crew||1 pilot, 1 copilot, 1 offensive systems officer, 1 defensive systems officer|
Illustrations by Basilisk https://basilisk2.deviantart.com
- This article was reprinted with permission from JoeBaugher.com
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- Illustrations by Basilisk https://basilisk2.deviantart.com