page_title: Lightweight Fighter program
section_title: Lightweight Fighter program
hierarchical_section_title: Lightweight Fighter program / History / Lightweight Fighter program
caption_attribution_description: General Dynamics YF-16 on display at the Virginia Air and Space Center in Hampton Virginia
context_page_description: The Lightweight Fighter program was a United States Air Force technology evaluation program initiated in the late 1960s by a group of officers and defense analysts known as the "Fighter Mafia". It was spurred by then-Major John Boyd's 'energy-maneuverability' theory, which indicated that excessive weight would have severely debilitating consequences on the maneuverability of an aircraft. Boyd's design called for a light-weight fighter with a high thrust-to-weight ratio, high maneuverability, and a gross weight of less than 20,000 lb, half that of its counterpart, the McDonnell Douglas F-15 Eagle. It resulted in the development of the General Dynamics YF-16 and Northrop YF-17. Late in the program, in 1974, with the promise of European sales, the Air Force changed the program name to Air Combat Fighter, and committed to purchasing 650 models of the YF-16, adopted as the F-16 Fighting Falcon. The U.S. Navy adopted a modified version of the YF-17 as the McDonnell Douglas F/A-18 Hornet.
context_section_description: The need for new air superiority fighters led the USAF to initiate two concept development studies in 1965: the Fighter Experimental (F-X) project originally envisioned a 60,000-pound (27,200 kg) class twin-engine design with a variable-geometry wing. This would be a very expensive aircraft, too expensive to consider equipping the entire Air Force with it as its standard aircraft. For this reason a less-expensive Advanced Day Fighter (ADF) was also considered, a lightweight design in the 25,000 lb (11,300 kg) class which would out-perform the MiG-21 by 25%.
  Boyd used his E-M theory to argue that the F-X design was far too heavy, and this led to new requirements for a smaller F-X in the 40,000-pound (18,100 kg) class. However, the appearance of the Mach-3-capable MiG-25 in July 1967 led to serious concerns within the Defense Department that the Soviets had developed a super fighter capable of outrunning anything the US fielded, while its huge wing would make it highly maneuverable. In response, the ADF effort was essentially ignored in favour of an all-out effort to develop a superior F-X, which would emerge as the F-15 Eagle.
  Boyd was unimpressed with the resulting weight growth in the F-15, and the shelving of the ADF. In the late 1960s he gathered a group of like-minded innovators that became known as the "Lightweight Fighter Mafia". In 1969, this "Fighter Mafia" was able to secure funds for a "Study to Validate the Integration of Advanced Energy-Maneuverability Theory with Trade-Off Analysis". General Dynamics received $49,000 and Northrop $100,000 study contracts to design concepts that embodied Boyd's E-M theory – a small, low-drag, low-weight, pure fighter with no bomb racks; their work would lead to the YF-16 and YF-17, respectively.
  Although the Air Force’s F-X proponents remained hostile to the concept because they perceived it as a threat to the F-15 program, the ADP concept (revamped and renamed as the "F-XX") gained civilian political support under the reform-minded Deputy Secretary of Defense David Packard, who favored the idea of competitive prototyping. As a result, in May 1971 the Air Force Prototype Study Group was established, with Boyd a key member. Two of its six proposals would be funded, one being the Lightweight Fighter (LWF). The Request for Proposals (RFP) was issued 6 January 1972, and called for a 20,000 lb (9,100 kg) class fighter with a good turn rate, acceleration and range, and optimized for combat at speeds of Mach 0.6–1.6 and altitudes of 30,000–40,000 ft (9,150–12,200 m). This was the region in which the USAF expected most future air combat to occur, based on studies of the Vietnam, Six-Day, and Indo-Pakistani wars. The anticipated average flyaway cost of a production version was $3 million.
  Five manufacturers – Boeing, General Dynamics, Lockheed, Northrop, and Vought – submitted proposals. The Vought V-1100 and the Lockheed CL-1200-2 Lancer were eliminated in March 1972. Though the Boeing Model 908-909 was initially most favored, it was quite similar in technology and appearance to the cheaper General Dynamics Model 401-16B. Since one of the goals of the program was to validate emerging technologies, Secretary of the Air Force Robert Seamans chose to select the General Dynamics and Northrop entries.
  The first YF-16 had its official maiden flight on 2 February 1974. The second YF-16 prototype first flew on 9 May 1974. This was followed by the first flights of the Northrop’s YF-17 prototypes, which were achieved on 9 June and 21 August 1974, respectively. The fly-off commenced in 1974 as both prototypes were delivered. The YF-16s would complete 330 sorties during the flyoff, accumulating a total of 417 flight hours; the YF-17s would accomplish 268 sorties.
caption: YF-16 on display at the Virginia Air and Space Center
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