The Republic XP-69 was an American fighter aircraft proposed by Republic Aviation in 1941 in response to a requirement by the United States Army Air Corps for a high-speed fighter. Manufacturers were encouraged to consider unorthodox designs; although the design was ordered as a prototype it was canceled because of delays with the engine that was to power it.
Development
The United States Army Air Corps began the R40-C fighter competition in February 1940. The competition encouraged manufacturers to propose unorthodox high-speed fighter aircraft that met the requirements of Type Specification XC-622.[1] The specification called for a single-engined high-performance fighter aircraft, with a maximum speed between 425 and 525 mph (684 and 845 km/h), armed with both machine guns and cannons, and be capable of landing on a 3,000 ft (910 m) long grass runway.[2]
Republic was one of six companies selected for the competition, and one of the aircraft proposed to the USAAC by Republic was the AP-12 Rocket. As proposed, the AP-12 was to be powered by a 2,500 hp Wright R-2160-3 Tornado 42-cylinder liquid-cooledradial engine mounted in the mid-section of the aircraft's streamlined, cigar-shaped fuselage, behind the cockpit, which drove a pair of three-bladed contra-rotating propellers.[1][3] It was to be armed with four nose-mounted machine guns firing through the propeller arc, and a single 20 mm cannon firing through the propeller hub.[1] The AP-12 placed 13th out of 26 contestants, forcing Republic to go back to the drawing board to improve its proposal.[1]
In July 1941, Republic submitted an improved design, the AP-18. The AP-18 had little in common with the AP-12. It retained the original aircraft's R-2160 engine, which was now mounted in the nose of a completely new small-cross section airframe.[4] The large radiator was to be mounted under the fuselage. The pressurized cockpit was to feature a bubble canopy, and an armament of four .50 in machine guns and two 37 mm cannons mounted in a laminar flow wing was planned.[4]
XP-69 mockup
In December 1941, the United States Army Air Forces (successor to the USAAC) ordered two prototypes of the AP-18 under the designation XP-69.[1] A mockup was built and was inspected by the USAAF in June 1942.[4][3] Construction of the first prototype began in November of that year.[3] However, due to development troubles and delays with the R-2160 engine, the XP-69 project was canceled in favor of a parallel development, the Republic XP-72, on May 24, 1943. By that time engineering on the project was 75% complete and the prototype was still in the early stages of construction, with the total program cost being $810,000.[3]
