Background On 8 October 1948, the board of senior officers of the
United States Air Force (USAF) issued recommendations that the service organize a competition for a new interceptor scheduled to enter service in 1954; as such, the all-new design would initially be dubbed the "1954 Ultimate Interceptor". Four months later, on 4 February 1949, the USAF approved the recommendation and prepared to hold a corresponding competition during the following year. In November 1949, the USAF decided that the new aircraft would be built around a
fire-control system (FCS). The FCS was to be designed before the airframe to ensure compatibility. The airframe and FCS together were called the weapon system. In January 1950, the USAF's
Air Materiel Command issued
request for proposals (RFPs) to 50 companies for the FCS, of which 18 responded. By May, the list was revised downward to 10. Meanwhile, a board at the U.S. Department of Defense headed by
Major General Gordon P. Saville reviewed the proposals, and distributed some to the
George E. Valley-led Air Defense Engineering Committee. Following recommendations by the committee to the Saville Board, the proposals were further reduced to two competitors,
Hughes Aircraft and
North American Aviation. Although the Valley Committee thought it was best to award the contract to both companies, Hughes was chosen by Saville and his team on 2 October 1950. In June 1950, the requirement for the airframe was formally issued; during January 1951, six aircraft manufacturers submitted nine responses. For the era, Convair's submitted design was relatively unorthodox, not only in terms of the delta wing configuration but the decision to carry all munitions within an internal weapons bay to reduce
drag; despite this, Republic's design was even more radical, proposing to use
ramjet propulsion to attain speeds in excess of Mach 3. The development of three different designs has been considered to be too expensive to proceed with, thus only Convair was permitted to do so in November 1951. From an early stage, USAF officials had decided to use the Cook-Craigie Plan for the aircraft's manufacturing; under this concept, production tooling and facilities would be created while a small pre-production batch of aircraft would be completed, the aim being to eliminate the need for a lengthy prototype program, instead incorporating any changes required into the production line. However, if substantial modifications were necessary, re-tooling would then become necessary as well. In December 1951, in order to accelerate the aircraft's development, it was proposed to equip the prototypes and pre-production aircraft with the less-powerful
Westinghouse J40 turbojet. During early 1953, by which point construction of the first aircraft had reached an advanced stage, it had become clear that there were serious design challenges present, including
wind tunnel testing that revealed early performance projections to have been overly optimistic. Furthermore, there had been sustained delays to both the
Curtiss-Wright J67 engine, a licensed derivative of the
Bristol-Siddeley Olympus which was still in development, and the MA-1 (formerly
MX-1179) FCS; to address the latter, decision makers opted to order an interim aircraft with the J40 and a simpler FCS (initially referred to as
E-9) into production as the
F-102A. being substituted for the prototypes and F-102As. This aircraft was intended to be temporary, pending the development of the more advanced F-102B, which would employ the more advanced J67. The F-102B would later evolve to become the F-106A, dubbed the "Ultimate Interceptor". On 23 October 1953, the
YF-102 prototype conducted its first flight from
Edwards Air Force Base, piloted by Convair's chief test pilot Richard L. Johnson. Its flying career was very brief as it was lost in an accident only nine days later during a failed attempt to reach Mach 1. The accident, which was caused by severe buffeting, seriously injured Johnson. The second aircraft flew on 11 January 1954, confirming a dismal performance.
Transonic drag was much higher than expected, and the aircraft was limited to Mach 0.98 (i.e. subsonic), with a ceiling of , far below the requirements.
Major redesign During mid 1953, Convair concluded that it needed to take action to address the F-102's shortcomings to prevent its cancellation, and promptly embarked on a major redesign effort. This redesign entailed the lengthening of the fuselage by , being "pinched" at the midsection (dubbed the "
Coke Bottle configuration"), with two large fairings on either side of the engine nozzle, with revised intakes and a new, narrower canopy. A more powerful model of the J57 was installed while the aircraft structure was also lightened. In parallel to this effort, the wing was also redesigned to be both thinner and wider. The
leading edge was reprofiled with a conical droop, with the apex at the root, as to improve handling at low speeds. Because the droop remained within the shock cone of the leading edge, the drag rise at supersonic speeds was minimal. A second, inboard fence was also added at the time. A new canopy was also adopted while the tail was shifted slightly aft. The level of changes that could be implemented were restrained by the redesign having occurred at such an advanced stage of development. Yet, the overall changes made were so substantial that two-thirds of the roughly 30,000 tools created to manufacture the YF-102 were scrapped or modified before quantity production had even commenced. The revised design quickly demonstrated that it could attain a speed of Mach 1.22 and a ceiling of . These performance improvements were sufficient for the USAF to agree to procure the F-102; accordingly, a new production contract was signed during March 1954. On 24 June 1955, the first flight of a production standard F-102 occurred. From the 26th production aircraft onwards, a taller vertical tail with a 40 percent greater surface area was fitted to counteract flutter and a lack of directional control at high speeds; existing aircraft were also retrofitted with this change.
Further development The production F-102A had the Hughes MC-3 FCS, which was later upgraded in service to the MG-10; it was used to locate enemy targets, steer interception courses, and control weapons deployment. The F-102 was the first USAF fighter to be designed without a gun, instead relying on missiles as its primary armament. The F-102 was later upgraded to allow the carrying of up to two
GAR-11/AIM-26 nuclear Falcon missiles in the center bay. The larger size of this weapon required redesigned center bay doors with no rocket tubes. Plans were considered to fit the
MB-1 Genie nuclear rocket to the design, but although a Genie was test fired from a YF-102A in May 1956, it was never adopted. The F-102 received several major modifications during its operational lifetime, with most airframes being retrofitted with
infra-red search and tracking systems,
radar warning receivers, transponders, backup
artificial horizons, and improvements to the
fire control system. A proposed close-support version (never built) would have incorporated an internal
Gatling gun, and an extra two
hardpoints for bombs, supplementing the two underwing pylons all production F-102s were fitted with for
drop tanks (the use of which reduced the craft to subsonic performance). To alleviate this, bigger internal fuel tanks and an
in-flight-refueling probe were fitted. The side-by-side seating design, popularized in the 1950s (and used with the American
Cessna T-37, British
Hawker Hunter T.7 and
English Electric Lightning T.4, among others), would require a redesign of the cockpit and a nose almost as wide as that of a Convair 340 commercial airliner. Development was put on hold despite being authorized on 16 April 1953 until issues with the fighter model were sufficiently addressed; the first firm order for the TF-102A was issued in July 1954, and a maiden flight made on 8 November 1955. The new nose introduced buffeting, the source of which was traced to the bulbous canopy. Vortex generators were added to the top of the canopy to prevent the buffet which had started at about Mach 0.72. The intake ducts were revised as the inlets were repositioned. Despite the many changes, the aircraft was combat-capable, although this variant was predictably slower, reaching only subsonic speeds in level flight. A total of 111 TF-102As were eventually manufactured. The numerous inherent design and technical limitations of the F-102 led to a proposed successor, initially known as the F-102B "Ultimate Interceptor". The improved design, in which the proposed Curtiss-Wright J67 jet engine was eventually replaced by a
Pratt & Whitney J75, underwent so many aerodynamic changes (including variable-geometry inlets) that it essentially became an entirely new aircraft and hence was redesignated and produced as the F-106 Delta Dart. Convair would also use a delta wing design in the Mach 2 class
Convair B-58 Hustler bomber. ==Operational history==