The Grumman XP-50 Skyrocket was a land based version of the Grumman XF5F-1, a twin engined single seat naval fighter, both of which only reached the prototype stage.
Work on the XF5F-1 began in 1938 when the US Navy placed an order for a single prototype of the Grumman G-34. This was a radical looking aircraft for 1938, with the leading edge of the wing passing in front of the short fuselage. It had a retractable tail wheel undercarriage, and was powered by two Wright XR-1820-40/ -42 Cyclone engines. It made its maiden flight in 1 April 1940, and although didn’t win a production contract itself, did help with the development of the Grumman XF7F.
In 1939 the USAAF issued Circular Proposal 39-755, looking for a new fighter design. Grumman submitted a version of the XF5F, the G-46. Although the Lockheed XP-49 won the contest, Grumman’s design came second. The USAAF was interested enough in the design to place a development contract for one prototype, the XP-50, on 25 November 1939.
This aircraft appears to have caused some confusion. Different sources list it as having serial number 39-2517 or 40-3057. However the highest serial number recorded for 1939 appears to be 39-856, for a North American BC-1A, and 40-3057 falls amongst a number of other experimental designs so appears to be the most likely.
The Air Force version differed from the Navy’s in three key areas. First it used a tricycle landing gear instead of the tail wheel type of the XF5F. Second, the fuselage was greatly lengthened so that the nose was well in front of the wing, to give room for the nose wheel of the tricycle landing gear (similar changes were made to the XF5F during its long testing process). Third, it was powered by a pair of turbocharged Wright R-1820-67/ -69 radial engines.
The XP-50 made its maiden flight on 18 February 1941, nearly a year after the XF5F. However it was less successful than the naval version, which remained in use until December 1944. The XP-50 suffered from problems with its engines overheating, and during a test flight on 14 May 1941 the right engine turbo compressor exploded, also damaging the undercarriage. Test pilot Bob Hall was able to bail out, and the aircraft crashed into Long Island Sound. Some sources suggest that this was the aircraft’s maiden flight, but a number of pictures exist of the aircraft in flight, which suggests that it had some successful flights before being lost.
By the time the XP-50 was lost Grumman were already working on a new twin engine design, the Grumman G-51. Only four days later the USAAC placed an order for a prototype of this, as the XP-65. The US Navy soon followed, with an order for a naval version of the same design, the XF7F Tigercat. The XP-65 would be cancelled soon after Pearl Harbor, but the F7F Tigercat enter production although too late for combat during the Second World War.
Engine: Two Wright XR-1820-67/ -69 turbocharged Cyclone 9-cylinder radial piston engines
Power: 1,200hp each
Span: 42ft 0in
Length: 28ft 8.5in
Height: 11ft 4in
Empty weight: 8,107lb
Maximum take-off weight: 10,138lb
Max speed: 383mph
Cruising speed: 210mph
Service ceiling: 33,000ft
Range: 1,200 miles
Armament: Two 23mm Madsen cannon