Convair B-58 Hustler
The Convair B-58 Hustler is a supersonic strategic bomber, the first capable of Mach 2 flight. Designed and produced by American aircraft manufacturer Convair, a division of General Dynamics, the B-58 was developed during the 1950s for the United States Air Force Strategic Air Command.
To achieve the high speeds desired, Convair chose a delta wing design used by contemporary interceptors such as the Convair F-102. The bomber was powered by four General Electric J79 engines in underwing pods. It had no bomb bay; it carried a single nuclear weapon plus fuel in a combination bomb/fuel pod underneath the fuselage. Later, four external hardpoints were added, enabling it to carry up to five weapons such as one Mk 53 and four Mk 43 warheads.
The B-58 entered service in March 1960, and flew for a decade with two SAC bomb wings: the 43rd Bombardment Wing and the 305th Bombardment Wing. It was considered difficult to fly, imposing a high workload upon its three-man crews. Designed to replace the subsonic Boeing B-47 Stratojet strategic bomber, the B-58 became notorious for its sonic boom heard on the ground by the public as it passed overhead in supersonic flight.
The B-58 was designed to fly at high altitudes and supersonic speeds to avoid Soviet interceptors, but with the Soviet introduction of high-altitude surface-to-air missiles, the B-58 was forced to adopt a low-level penetration role that severely limited its range and strategic value. It was never used to deliver conventional bombs. The B-58 was substantially more expensive to operate than other bombers, such as the Boeing B-52 Stratofortress, and required more frequent aerial refueling. The B-58 also suffered from a high rate of accidental losses. These factors resulted in a relatively brief operational career of ten years. The B-58 was succeeded in its role by the smaller, also problem-beset, swing-wing.
Development
Origins
The genesis of the B-58 was the Generalized Bomber Study issued in February 1949 by the Air Research and Development Command at Wright-Patterson AFB, Ohio, for the development of a supersonic, long-range, manned bomber aircraft. ARDC sought the best attainable quantitative data, challenging the industry to devise their own solutions to attain the stated goal. Work on the proposed bomber's design was to begin less than two years after sustained supersonic flight had been achieved. According to aviation authors Bill Gunston and Peter Gilchrist, while some military officials were keenly interested in the prospective use of supersonic bombers, others held doubts about the propulsion systems and materials science required for supersonic operations, as well as the much higher fuel consumption relative to subsonic counterparts.Despite the skepticism, multiple contractors submitted bids for GEBO II, which was viewed as an influential step towards a development contract. These included Boeing, Convair, Curtiss, Douglas, Martin, and North American Aviation. Most of the submissions were relatively straightforward, unambitious, and expensive. Convair, which had built the XF-92A and other delta-wing fighters, evaluated swept and semidelta configurations, then settled on the delta wing, which offered good internal volume for support systems and fuel. It also provided low wing loading for the airframe size, permitting supersonic flight in the midstratosphere at. Most of the configurations studied mated the delta wing to a relatively slender fuselage housing a crew of two and powered by a pair of jet engines.
The Convair proposal, coded FZP-110, was a radical, two-place, delta-wing bomber powered by three General Electric J53 turbojet engines. The performance estimates included a speed and a range. A key feature of the design was to store consumables, both weaponry and most of the fuel, within a large external pod, which enabled a smaller fuselage. In January 1951, Convair submitted the FZP-110 proposal, which was received later than other competing bids. During December 1951, a revised FZP-016 proposal was submitted, which deleted the third engine on the tail, increased the remaining two engines' thrust, and added a third crew member to operate defensive systems.
Selection
The USAF chose Boeing's MX-1712 and Convair MX-1626 design studies to proceed to a phase 1 study. During this period, Convair took advantage of recent developments by General Electric and replaced the two large J53 engines with four smaller J79s optimized for supersonic flight. The recently formulated area rule was also applied to the design, resulting in aerodynamic reprofiling and an even more slender fuselage. Having been refined, Convair redesignated their renewed submission MX-1964.In August 1952, Convair's design was judged superior. According to Gunston and Gilchrist, Boeing's submission was viewed as equally good, but their separate contract to produce the Boeing B-52 Stratofortress had undoubtedly influenced this competition. In December 1952, Convair was chosen to meet the new SAB-51 and SAR-51 standards, the first general operational requirements for supersonic bombers. In February 1953, the USAF issued a contract for Convair's design, designated B-58 on 10 December 1952.
The B-58 program, unlike those for prior military aircraft, was the first weapon-system contract. Under this arrangement, Convair acted as the prime contractor responsible for all program elements, not just the aircraft. Convair was required to devise or subcontract everything associated with the aircraft's operation, from the engines to training manuals, spare components, and software, in excess of one million items. Early on, the contract was modified to build a pair of XB-58 prototypes, 11 YB-58A preproduction aircraft, and 31 mission pods including a free-fall bomb pod, a rocket-propelled controllable bomb pod, a reconnaissance pod, and an electronic reconnaissance pod.
Into flight
The first prototype, serial number 55-660, was rolled out on 31 August 1956. The program was performed under high security; prior to the roll out, no unauthorized individual had knowledge of its shape or basic configuration. On 11 November 1956, the maiden flight occurred. The prototype exceeded Mach 1 for the first time on 30 December of that year. The difficult and protracted flight-test program involving 30 aircraft continued until April 1959. In total, 116 B-58s were produced - 30 trial aircraft and 86 production B-58A models. Most of the trial aircraft were later upgraded to operational standards. Eight were equipped as TB-58A training aircraft.Convair sought further development of the B-58, proposing variants and derivatives for both military and civilian applications. Most never went beyond the drawing board, having been ordered prior to the decision to terminate multiple contracts. The B-58B, B-58C, B-58D, and B-58E variants were all terminated prior to completion of any production aircraft. During the late 1960s, some refinements to the existing fleet were developed and introduced, such as slender bomb racks and additional pods. The final B-58 was delivered in October 1962.
Design
Overview
The Convair B-58 Hustler was a high-speed strategic bomber, capable of routinely attaining Mach 2 at altitude. It incorporated a large delta wing with a leading-edge sweep of 60°, and was powered by an arrangement of four General Electric J79-GE-1 turbojet engines. Although its sizable wing generated relatively low wing loading, it proved to be surprisingly well suited for low-altitude, high-speed flight. To protect against the heat generated while cruising at Mach 2, the crew compartment, wheel wells, and electronics bay were pressurized and air conditioned. The B-58 was one of the first extensive applications of aluminum honeycomb panels, which bonded outer and inner aluminum skins to a honeycomb of aluminum or fiberglass.Various features of the B-58 were considered to be record-breaking, according to Gunston and Gilchrist. The structure itself made up 13.8% of the aircraft's gross weight, an exceptionally low figure for the era, while the wing was considered to be extremely thin, as well. Several key features of the engine, including the nacelle and the inlet, were unlike any existing aircraft, having been devised from guidance by aerodynamicists. Specifically, the inlets used moving conical spikes, being fully aft on the ground and at low speeds to maximize air intake, then driven forward while being flown at high speeds to minimize the annular gap. This movement was automatically controlled, but significant noise and asymmetric thrust were generated in the event of a single inlet malfunctioning.
Crew provisions
The B-58 was operated by a crew of three: pilot, radar navigator/bombardier, and defense systems operator. They were seated in separated tandem cockpits. The AC's cockpit, which was provided with very deep windows, was considered to be mostly conventional for a large multiengine aircraft. The DSO was provisioned with a complex arrangement of different systems, which Gunston and Gilchrist describe as being the most complicated of any aircraft of the era. The space allocated to the crew, despite being roughly half of the fuselage's internal volume, was typically considered to be cramped and claustrophobic.Later versions of the B-58 provided each crew member with a novel ejection capsule that could eject at an altitude of at speeds up to Mach 2. Unlike standard ejection seats of the period, a protective clamshell enclosed the seat and the control stick with an attached oxygen cylinder, allowing the AC to continue to fly even "turtled up" and ready for immediate egress. The capsule was buoyant; the crewmember could open the clamshell and use it as a life raft. Unusually, the ejection system was tested with live bears and chimpanzees; it was qualified for use during 1963. While it has occasionally been written that one of these test bears became the first living being to survive a supersonic ejection, this is not the case; the first supersonic ejection was made in 1955 by George F. Smith from a North American F-100 Super Sabre.
The electronic controls were ambitious and advanced for the day. The Nav and DSO's cockpits featured wraparound dashboards with warning lights and buttons, and automatic voice messages and warnings from a tape system were audible through the helmet sets. Research during the era of all-male combat aircraft assignments revealed that a woman's voice was more likely to gain the attention of young men in distracting situations. Nortronics Division of Northrop Corporation selected actress and singer Joan Elms to record the automated voice warnings. To those flying the B-58, the voice was known as "Sexy Sally". The original voice recordings are archived.