Editing Lockheed XF-90 (section)

==Design and development==
[[File:Lockheed F-90.jpg|right|thumb]]In response to a 1945 Army request for an advanced jet fighter, Lockheed proposed a jet powered initially by a [[Lockheed J37|Lockheed L-1000]] axial flow turbojet, and then the [[General Electric J35]].<ref>Jenkins 2008, p. 138.</ref> Further design refinements included using two [[Westinghouse J34]] engines with afterburners. After data showed that a [[delta wing|delta]] [[planform]] would not be suitable, the Lockheed Model 90 was built in 1947 as a mock-up.<ref>O'Leary 1994, p. 18.</ref>

The final design embodied much of the experience and shared the intake and low-wing layout of the previous [[Lockheed F-80 Shooting Star|P-80 Shooting Star]], but with 35° [[swept wing|swept-back wings]], a sharply-pointed nose, and two [[Westinghouse J34|Westinghouse J34-WE-11]] axial-flow turbojet engines, providing a total thrust of 6,200&nbsp;lbf (27.6&nbsp;kN), mounted side-by-side in the rear fuselage and fed by side-mounted air intakes.<ref name="Jones p. 241"/> The wings had leading edge slats, Fowler flaps, and ailerons on the trailing edge. The pressurized cockpit was fitted with an ejection seat and a bubble canopy. Proposed armament was six 20&nbsp;&nbsp;mm (.79&nbsp;in) cannons. The internal fuel was supplemented by wingtip-mounted tanks, bringing total fuel capacity to 1,665&nbsp;gal (6,308&nbsp;L). The use of 75ST aluminum rather than the then-standard 24ST aluminum alloy, along with heavy forgings and machined parts, resulted in a well-constructed, sturdy airframe. These innovations resulted in an aircraft with an empty weight more than 50% heavier than its competitors.<ref name="Jones p. 241"/>

The first XF-90 used non-afterburning J34s, but these lacked the thrust for takeoff as rocket-assisted RATO were required for most of the first flights unless it carried a very low fuel load. The second (XF-90A) had afterburners installed which had been tested on an [[P-80 Shooting Star|F-80]] testbed. Even so, the aircraft remained underpowered.<ref name="Jones p. 241"/>