Lightweight Fighter

The Lightweight Fighter (LWF) program was a U.S. Air Force technology evaluation program initiated in the 1960s by a cabal of officers and defense analysts known as the "fighter mafia". It was spurred by then Maj. John Boyd's Energy-Maneuverability (E-M) theory of maneuverability, which indicated that excessive weight would have severely deblilitating consequences on the maneuverability of an aircraft. The new aircraft was to be a light weight fighter with a high thrust-to-weight ratio, a gross weight of less than 20,000 pounds (half that of its counterpart, the F-15 Eagle), and high maneuverability. It resulted in the development of the YF-16 and YF-17; the latter would be adopted by the U.S. Navy as the F/A-18. Late in the program, in 1974, with the promise of European sales, the Air Force changed the program name to Air Combat Fighter (ACF), and committed to purchasing 650 models of the YF-16, adopted as the F-16 Fighting Falcon.

History

In the 1960s, both the U.S. Air Force and U.S. Navy were in the process of acquiring large, heavy fighters designed primarily to fight with missiles at long range. Project Forecast, a 1963 Air Force study, attempted to identify future weapons trends and "certain high-priority areas for R&D, recommendations based on the greatest potential payoff for the future." [ [http://www.airpower.au.af.mil/airchronicles/aureview/1969/sep-oct/schriever.html Technology and Aerospace Power in the 1970s] , General Bernard A. Schiriever, USAF (Ret), Air University Review, September-October 1969] As was strongly affirmed by Project Forecast, the U.S. Air Force and Navy both concluded during the early 1960s that the future of air combat would be determined by increasingly sophisticated missiles. Future "fighters" would be designed primarily for long range, high speed, and equipped with extremely large radar systems in order to detect and engage opposing fighters at beyond visual range (BVR). This made them much more like interceptors than classic fighter designs, and led to increasingly heavier and more technologically sophisticated designs – and thus costlier. In the early 1960s, both the Air Force and Navy expected to use the F-111 (then still in development as the TFX) and F-4 Phantom II for their long- and medium-range needs. The perception of a declining need for close-in “dogfighting” capabilities resulted in the original decision to not install internal cannons in the Phantom.Richardson 1990. pp. 6–7.] Jenkins, Dennis R. "F/A-18 Hornet: A Navy Success Story". New York: McGraw-Hill, 2000. ISBN 0071346961.]

However, real-world experience in the Vietnam War revealed some shortcomings in American fighter capabilities, as early-generation Soviet-bloc jet fighters proved to be more of a challenge than expected for U.S. designs. Even though U.S. pilots had achieved favorable kill-to-loss ratios, combat had revealed that air-to-air missiles (AAM) of this era were significantly less reliable than anticipated. Furthermore, the rules of engagement in Vietnam precluded long-range missile attacks in most instances, as visual identification was normally required. Under these conditions, combat invariably closed to short ranges where maneuverability and short-range air-to-air weapons became critical, even for dedicated interceptors like the F-102 Delta Dagger. [Higham, Robin & Williams, Carol. "Flying Combat Aircraft of USAAF-USAF (Vol.2)". Manhattan, Kansas: Sunflower University Press, 1978. ISBN 0-8138-0375-6.]

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 in July 1967 would result 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.Richardson 1990, p. 7.]

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 of the value of aircraft specific energy maintenance as an advantage in fighter combat. Maneuverability was the means of getting “inside” an adversary’s decision-making cycle, a process Boyd called the “OODA” loop (for “Observation-Orientation-Decision-Action”). This approach emphasized an aircraft design capable of “fast transients” –quick changes in speed, altitude, and direction. A fighter that is superior in its ability to gain or lose energy while out-turning an opponent can initiate and control any engagement opportunity; a fast transient capability allows the pilot to stay inside a hard-turning opponent when on the offensive or to force an overshoot of an opponent when on the defensive. These parameters called for a small, lightweight aircraft – which would minimize drag and increase the thrust-to-weight ratio – but a larger, higher-lift wing to minimize wing loading – which tends to reduce top speed while increasing payload, and can lower range (which can be compensated for by increased fuel in the larger wing).Hillaker, Harry (July 1997). [http://www.codeonemagazine.com/archives/1997/articles/jul_97/july2a_97.html “Tribute To John R. Boyd”] . "Code One". Retrieved 7 June 2008.] Hehs, Eric (April & July 1991). [http://www.codeonemagazine.com/archives/1991/articles/jul_91/july2a_91.html “Harry Hillaker – Father of the F-16”] . "Code One". Retrieved 7 June 2008.]

Boyd’s theories helped restrain the F-15’s growth into a very large design that threatened to turn into an “F-111 Mark II”, but it strengthened his conviction that the F-15 would need to be complemented by larger numbers of smaller fighters – the “high/low mix” – as had been the case with previous twin-engine fighters. In the late 1960s he 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 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.Richardson 1990, pp. 7–8.] [Coram, Robert. "Boyd: the Fighter Pilot Who Changed the Art of War". New York: Little, Brown, and Co., 2002. ISBN 0-316-88146-5.]

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 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, and two of its 6 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. [Peacock 1997, pp. 9–10.] Richardson 1990, pp. 7–9.]

Five manufacturers - Boeing, General Dynamics, Lockheed, Northrop, and Vought - submitted proposals. Vought's V-1100 and Lockheed's CL-1200 "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 fly-off commenced in 1974 as both prototypes were delivered. Concurrently, Belgium, Denmark, Norway, and the Netherlands had formed the Multinational Fighter Program Group (MFPG) to select a replacement for their F-104s from among the Dassault Mirage F.1, YF-16, YF-17, and JA 37 Viggen. They indicated that the winner of the LWF contest would be the favored candidate. Up to this point, the LWF was merely an evaluation program with no plans to purchase models, but the possibility of a European order lead the Pentagon to reconsider. The Air Force was now seeking a multi-role fighter to replace the F-4 and F-105, so the program was renamed the Air Combat Fighter (ACF). In September 1974, the Air Force announced plans to purchase 650 ACFs. On 13 January, 1975, Secretary of the Air Force John McLucas announced the selection of the YF-16. In May 1975, the US Navy choose the YF-17 over the YF-16 in the Navy Air Combat Fighter (NACF) competition. It would be developed into the carrier-capable F/A-18 Hornet. [Donald, David ed. "Boeing F/A-18 Hornet", "Warplanes of the Fleet". AIRtime, 2004. ISBN 1-880588-81-1.]

References

*cite web
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first = Col. Marshall
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title = The Revolt of the Majors: How the Air Force Changed After Vietnam (and Saved the World)
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*Richardson, Doug. "General Dynamics F-16 Fighting Falcon". London: Salamander Books, 1990. ISBN 0-86101-534-7.