Republic XP-69

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-cooled radial 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]

Data from [4][3]

General characteristics

• Crew: 1
• Length: 51 ft 6 in (15.70 m)
• Wingspan: 51 ft 8 in (15.75 m)
• Height: 17 ft (5.2 m)
• Wing area: 505 sq ft (46.9 m²)
• Airfoil: NACA 66-114 at root, NACA 66-213 at tip[5]
• Empty weight: 15,595 lb (7,074 kg)
• Gross weight: 18,655 lb (8,462 kg)
• Max takeoff weight: 26,164 lb (11,868 kg)
• Powerplant: 1 × Wright R-2160-3 Tornado 42-cylinder turbo-supercharged liquid-cooled radial engine, 2,500 hp (1,900 kW)
• Propellers: 6-bladed Hamilton Standard contra-rotating propellers, 13.7 ft (4.2 m) diameter

Performance

• Maximum speed: 450 mph (720 km/h, 390 kn)
• Range: 1,800 mi (2,900 km, 1,600 nmi)
• Service ceiling: 48,900 ft (14,900 m)
• Rate of climb: 2,750 ft/min (14.0 m/s)

Armament

• Guns:
  
  • 4 × .50 in (12.7 mm) machine guns (1,280 rounds)
  • 2 × 37 mm cannons (80 rounds)

Aircraft of comparable role, configuration, and era

• Curtiss-Wright XP-55 Ascender
• Vultee XP-54
• Northrop XP-56
• Bell XP-52
• Grumman F6F Hellcat
• Vought F4U Corsair
• Republic P-47 Thunderbolt
• Focke-Wulf Fw 190
• Hawker Typhoon
• Hawker Tempest
• Mitsubishi A7M
• North American P-51 Mustang

Related lists

• List of aircraft of World War II
• List of military aircraft of the United States
• List of fighter aircraft