F16

Origins
Real-world experience in the Vietnam War revealed some shortcomings in American fighter capabilities, and the need for better air-to-air training for fighter pilots.[8] The need for new air superiority fighters led the USAF to initiate two concept development studies in 1965: the Fighter Experimental (FX) project originally envisioned a 60,000 lb (27,200 kg) class twin-engine design with a variable-geometry wing, and the Advanced Day Fighter (ADF), a lightweight design in the 25,000 lb (11,300 kg) class which would out-perform the MiG-21 by 25%. However, the first appearance of the Mach-3-capable MiG-25 'Foxbat' in July 1967 resulted in the ADF effort being deemphasized in favor of the FX program, which would produce the F-15, a 40,000 lb (18,100 kg) class aircraft.[9]

Based on his experiences in the Korean War and as a fighter tactics instructor in the early 1960s Colonel John Boyd and mathematician Thomas Christie developed the Energy-Maneuverability (E-M) theory to model a fighter aircraft's performance in combat. Maneuverability was the key to a process Boyd called the "OODA Loop" (for "Observation-Orientation-Decision-Action"). Boyd's work called for a small, lightweight aircraft with an increased thrust-to-weight ratio.[10][11] A 1965 Air Force study suggested equipping its squadrons with a mix of high and low cost fighters as being the most economical.[12]


Lightweight Fighter program
Main article: Lightweight Fighter
In the late 1960s Boyd gathered around him a group of like-minded innovators that became known as the "Lightweight Fighter Mafia". In 1969, the "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 $149,000 and Northrop $100,000 to develop 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.[13][14]

Although the Air Force’s FX proponents remained hostile to the concept because they perceived it as a threat to the F-15 program, the ADF 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, and two of its six proposals would be funded, one being the Lightweight Fighter (LWF) proposal. The Request for Proposals issued 6 January 1972 called for a 20,000 lb (9,100 kg) class air-to-air day 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. This production plan, though, was only notional as the USAF was under no obligation to acquire the aircraft and, in fact, had no firm plans to procure the winner, which was to be announced in May 1975.[15][16]

Five companies responded and in March 1972, the Air Staff announced the winners for the follow-on prototype development and testing phase were Boeing’s Model 908-909 and General Dynamics’ Model 401; however, after further review, the Source Selection Authority (SSA) would demote Boeing’s entry to third place, after Northrop’s P-600. GD and Northrop were awarded contracts worth $37.9 million and $39.8 million to produce the YF-16 and YF-17, respectively, with first flights of both prototypes planned for early 1974. To overcome resistance in the Air Force hierarchy, the 'Fighter Mafia' and other LWF proponents successfully advocated the idea of complementary fighters in a high-cost/low-cost force mix (in part, to be able to afford sufficient fighters to sustain overall USAF fighter force structure requirements); this "high/low mix" concept would gain broad acceptance by the time of the flyoff between the prototypes, and would define the relationship of the F-15 and F-16 – and, subsequently, the F-22 Raptor and F-35 Lightning II.[17][18]


Flyoff

An air-to-air right side view of a YF-16 aircraft and a Northrop YF-17 aircraft, side-by-side, armed with AIM-9 Sidewinder missilesThe first YF-16 was rolled out on 13 December 1973, and its 90-minute-long “official” first flight was made at the Air Force Flight Test Center (AFFTC) at Edwards AFB, California, on 2 February 1974. Its actual first flight occurred accidentally during a high-speed taxi test on 20 January. While gathering speed, a roll-control oscillation caused a fin of the port-side wingtip-mounted missile and then the starboard stabilator to scrape the ground, and the aircraft then began to veer off the runway. The GD test pilot, Phil Oestricher, decided to lift off to avoid wrecking the machine, and safely landed it six minutes later. The slight damage was quickly repaired and the official first flight occurred on time. The YF-16’s first supersonic flight was accomplished on 5 February 1974, and the second YF-16 prototype flew for the first time 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. Altogether, the YF-16s would complete 330 sorties during the flyoff, accumulating a total of 417 flight hours; the YF-17s would accomplish 268 sorties.[19]