For those who got a slapping for thread hijacking with a P-80A vs Me-262 debate. Little extra info on the X/YP-80A, we usually hear more about the 262. Lockheed was selected in mid43 for a contract to develop a combat worthy jet fighter to succeed the XP-59A. The design requirement was to use the De Havilland H-1B turbojet to be license produced, a centrifugal design completely different to the German Jumo. Another requirement was a test airframe ready to fly in 180 days. Kelly Johnson completed the prototype, named Lulu-Belle in 143 days. January 9, 1944 the XP-80 flew at Muroc with Milo Burcham at the controls and the De Havilland motor (same as the kind used in the Vampire and MiG-15). Max initial climb rate was 3000fpm, maximum level speed reached 502mph at 20,480ft and usable ceiling reached 41,000ft. But the license producer of the De Havilland jet were encountering engineering difficulties and the USAF wanted an alternate engine. General Electric was working on its own license produced axial thrust engine called the I-40, production designation J33. They authorised Lockheed to build a prototype with this engine. The second prototype, designated XP-80A and called Gray Ghost for its paint scheme was completed in 132 days. It was similar looking but bigger and weighed 25% more than Lulu-Belle, plus was fitted with rudimentary cockpit pressurisation. Tony Le Vier flew it on June 11, 1944. He noted it was longitudinally unstable without gun/ammunition ballast, this issue haunted the production series as all P-80 become unstable when the ammo runs out, it's one of the only aircraft which are ferried with guns/ammo. There was a lot of bugfixing to do like sorting cockpit air conditioning, temperatures reached 180F and blistered Le Vier's skin. It was fixed by combining it with a refrigeration system. And a faulty tachometer had almost caused an accident due to incorrect engine settings. Le Vier was also identifying new phenomenae peculiar to jet flight, such as "inlet rumble" caused by boundary layer air around the engine inlets, which can induce directional snaking of the aircraft. Engine flameouts at high or low altitudes were also commonplace. A second XP-80A prototype in a bare metal finish was made, called the Silver Ghost. Wingtip fuel tanks were tested on this airframe. Following this a preproduction series were built to the same configuration for service testing, the YP-80A. Over the course of testing, using the GE-J33 max initial rate of climb leapt to 5000fpm, top speed an easy 550mph and usable ceiling passed 45,000ft with ballast for war armament loadouts. Then the YP-80A started killing pilots. Milo Burcham died in one when a fuel governer failed (overspeeding the turbine at about 50ft above ground on take off, it was messy). Dick Bong, a Pacific ace was flying a new YP-80A when a similar engine failure claimed his life. Then one tried to kill Tony Le Vier, destroying the Gray Ghost XP-80A testbed (he had a reputation for roaming around the aerodrome at speeds exceeding 575mph in it). Nobody could figure out why it suddenly shed its tail following a mechanical shudder in flight. Then Army pilot Van Nuys managed to bring a YP-80A to a belly landing after experiencing another engine failure. Investigators found substandard manufacture of turbine blades were causing the failures, which was due to the industrial processes used to make them in the US. The turbine shed blades and the blades buzzsawed through tailplanes and fuselage sections during flight. This took time to find, and fix. It would've precluded successful use of the type during the war years, if it was put in front line service in 1945, the P-80A would've been dropping like flies to turbine failures. By 1947 the P-80 was sorted and a specially prepared P-80R set an airspeed record of 623.738mph over Muroc.