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The Lockheed XP-49 was a design for a more powerful fighter to be based on the P-38 Lightning, but it never got beyond the prototype stage, and by the time the prototype was ready, it was outclassed by existing P-38s.
On 11 March 1939 the US Materiel Division issued a proposal for a new interceptor fighter. In order to speed up the development of these aircraft, the Air Corps suggested that existing airframes could be matched with newer engines to produce faster aircraft.
Lockheed came up with a proposal for an improved version of the P-38 Lightning. It would have larger fuel tanks, a pressurised cabin and Pratt & Whitney X-1800-SA2-G (XH-2600) 2,000-2,200hp engines for the prototypes and Wright R-2160 Tornado 2,300hp engines for the production aircraft, in both cases using turbo-superchargers. The new aircraft was predicted to have a top speed of 473mph at 20,000ft for the prototype and 500mph at 20,000ft for the production version.
Four companies put forward designs for the new fighter. On 25 November 1939 Grumman were given a contract to produce a prototype of their XP-50, a modified version of the XF5F. Lockheed’s contract was drawn up on 30 November 1939, but not issued until 8 January 1940.
In March 1940 Lockheed, with the support of the Air Corps, made the decision that would doom the project. They decided that the 2,300hp engines would have left the aircraft over powered, and decided to swap to the Continental XIV-1430-9/ 11 twelve cylinder liquid cooled inverted vee engine, expected to produce 1,540hp at take off and with a pair of engines that drove their propellers in opposite directions to eliminate the problems of torque. This engine was still under development, and in the end didn’t enter large scale production.
The airframe was to be very similar to the P-38, apart from the engine fittings, a stronger undercarriage and the pressurized cabin. Two thirds of the components were shared with the P-38, speeding up the production of Lockheed’s part of the prototype.
Work on the P-49 began to speed up late in 1940. Detailed design work began on 23 December 1940, and mock up inspection was completed on 28 August 1941. The prototype was soon completed, but the first engines weren’t received until 22 April 1942, at which point they still hadn’t been cleared for flight. The prototype was finally ready for its maiden flight on 14 November 1942.
After three flights the P-49 was given new XIV-1430-13/ -15 engines, rated at 1,350hp at take off and 1,600hp at 25,000ft. Its new Royalin fuel tanks, which were causing some problems, were replaced with standard P-38 self sealing tanks. A seat for a flight engineer was added behind the pilot’s seat. Test flights then resuming in December 1942, but on 1 January 1943 the prototype was damaged in single engine emergency landing caused by a hydraulic line and electrical failure. The port undercarriage collapsed during the landing, causing more damage.
While the aircraft was being repaired it was given a taller vertical tail. It was finally delivered to the Air Corps at Wright Field on 26 June 1943, 27 months late! By this point it was already outclassed by the P-38J Lightning, which had a better top speed at higher altitude than the P-49. This combined with its use of an engine that wasn’t in large scale production to make sure that no further aircraft were produced. The P-49 prototype was eventually used in tests on hard landings which involved dropping it from a bridge crane. The damaged aircraft was scrapped in 1946.
Engines: Two Continental XIV-1430-13/ -15
Power: 1,350hp at take off, 1,600hp at 25,000ft (per engine)
Crew: 1
Wing span: 52ft
Length: 40ft 1in
Height: 9ft 9.5in
Empty weight: 15,464lb
Loaded weight: 19,950lb
Maximum weight: 22,000lb
Maximum speed: 406mph at 15,000ft; 347mph at sea level
Cruising speed: 372mph
Rate of climb: 3,280ft/ min
Service ceiling: 37,500ft
Normal range: 680 miles
Maximum range: 1,800 miles
Lockheed Aircraft Since 1913, René J Francillon