Editing McDonnell Douglas F-15 Eagle (section)

===Early studies===
The F-15 can trace its origins to the early [[Vietnam War]], when the [[United States Air Force|U.S. Air Force]] and [[United States Navy|U.S. Navy]] fought each other over future tactical aircraft. [[United States Secretary of Defense|Defense Secretary]] [[Robert McNamara]] was pressing for both services to use as many common aircraft as possible, even if performance compromises were involved. As part of this policy, the USAF and Navy had embarked on the [[General Dynamics F-111 Aardvark|TFX (F-111)]] program, aiming to deliver a medium-range [[interdiction aircraft]] for the Air Force that would also serve as a long-range [[interceptor aircraft]] for the Navy.{{sfn|Neufeld|2007|p=42}}

In January 1965, Secretary McNamara asked the Air Force to consider a new low-cost tactical fighter design for short-range roles and [[close air support]] to replace several types like the [[North American F-100 Super Sabre|F-100 Super Sabre]] and various [[light bomber]]s then in service. Several existing designs could fill this role; the Navy favored the [[Douglas A-4 Skyhawk]] and [[LTV A-7 Corsair II]], which were pure [[attack aircraft]], while the Air Force was more interested in the [[Northrop F-5]] fighter with a secondary attack capability. The A-4 and A-7 were more capable in the attack role, while the F-5 less so, but could defend itself. If the Air Force chose a pure attack design, maintaining air superiority would be a priority for a new [[airframe]]. The next month, a report on light tactical aircraft suggested the Air Force purchase the F-5 or A-7, and consider a new higher-performance aircraft to ensure its air superiority. This point was reinforced after the loss of two [[Republic F-105 Thunderchief]] aircraft to obsolete [[MiG-17]]s attacking the [[Thanh Hóa Bridge]] on 4 April 1965.{{sfn|Neufeld|2007|p=42}}

In April 1965, [[Harold Brown (Secretary of Defense)|Harold Brown]], at that time director of the [[Assistant Secretary of Defense for Research and Engineering|Department of Defense Research and Engineering]], stated the favored position was to consider the F-5 and begin studies of an "F-X".<ref group=N>"F-X" should be read as "Fighter, Unknown designation number", but is often translated as "Fighter-Experimental".</ref> These early studies envisioned a production run of 800 to 1,000 aircraft and stressed maneuverability over speed; it also stated that the aircraft would not be considered without some level of ground-attack capability.{{sfn|Neufeld|2007|p=43}} On 1 August, General [[Gabriel P. Disosway|Gabriel Disosway]] took command of [[Tactical Air Command]] and reiterated calls for the F-X, but lowered the required performance from Mach 3.0 to 2.5 to lower costs.{{sfn|Neufeld|2007|p=44}}

[[File:220725-F-F3405-0004.jpg|thumb|Test facility craftsman [[Jack Culpepper]] adjusts a model of the F-15 Eagle before it undergoes aerodynamic testing in the mid-1970s in the 4-foot transonic wind tunnel at Arnold Air Force Base, Tennessee]]
An official requirements document for an air superiority fighter was finalized in October 1965, and sent out as a [[request for proposal]]s to 13 companies on 8 December. Meanwhile, the Air Force chose the A-7 over the F-5 for the support role on 5 November 1965,<ref>Munzenmaier, Walter. "'LTV A-7D/K Corsair II: The 'SLUF' in USAF and USANG Service 1968–1993," Famous Aircraft of the USAF and USAG, Volume 1.</ref> giving further impetus for an air superiority design as the A-7 lacked any credible air-to-air capability.

Eight companies responded with proposals. Following a downselect, four companies were asked to provide further developments. In total, they developed some 500 design concepts. Typical designs featured [[variable-sweep wing]]s, weight over {{convert|60000|lb|kg}}, included a top speed of [[Mach number|Mach]] 2.7 and a [[thrust-to-weight ratio]] of 0.75.<ref name=Jenkins_p5-7>Jenkins 1998, pp. 5–7.</ref> When the proposals were studied in July 1966, the aircraft were roughly the size and weight of the TFX F-111, and like that aircraft, were designs that could not be considered an air-superiority fighter.{{sfn|Neufeld|2007|p=46}}