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One of the first aircraft built by the newly formed McDonnell Aircraft Corporation, the XP-67 was developed from an earlier design study for a long-range fighter. This earlier design, though rejected by the Army Air Corps, showed sufficient innovation to warrant the allocation of development funds. McDonnell came up with a new design and on July 29, 1941 this project received the designation of XP-67 and two prototypes were ordered.

The McDonnell design team created an interesting looking aircraft by using airfoils whenever possible, forming a design that seems to have the various components merge together. The XP-67 was fitted with a pressurized cabin and powered by two Continental XI-1430 engines equipped with GE D-2 Turbo-Superchargers driving four-bladed propellers. The original armament was to be six .50 machine guns and four 20mm cannon later changed to six 37mm M-4 cannon though studies were made to equip the aircraft with a 75mm cannon.

Ground trials began in early December but halted on the 8th when fires started in both nacelles during an engine run-up. The problem was identified as a malfunction of the exhaust manifold slip rings and delayed the flight trials for nearly a month. Flight testing commenced on January 6, 1944 but the first flight was aborted due to engine problems. Various modification were made and flight testing resumed but was once again halted when on the fourth flight the engines were overspeeded resulting in the bearings burning themselves out.

Due to parts being unavailable the aircraft was returned to McDonnell where modifications to the tailplane were undertaken. It wasn't until March 23, 1944 that flight testing resumed. Despite repeated modifications the aircraft suffered from generally poor performance and dangerous handling characteristics. On September 6th, 1944 the prototype was severely damaged by fire and it was decided that the second prototype would require too much time to complete and the development contract was canceled.



General characteristics

* Crew: one, pilot
* Length: 44 ft 9¼ in (13.65 m)
* Wingspan: 55 ft (16.76 m)
* Height: 15 ft 9 in (4.80 m)
* Wing area: 414 ft² (38.50 m²)
* Empty weight: 17,745 lb (8,049 kg)
* Loaded weight: 22,114 lb (10,031 kg)
* Max takeoff weight: 25,400 lb (11,521 kg)
* Powerplant: 2× Continental XIV-1430-17/19 twelve cylinder inverted vee liquid-cooled engine, 1,350 hp (1,007 kW) each

Performance

* Maximum speed: 405 mph (352 knots, 650 km/h) at 25,000 ft (7,600 m)
* Cruise speed: 270 mph (235 knots, 435 km/h)
* Range: 2,385 mi (2,074 nmi, 3,837 km)
* Service ceiling: 37,400 ft (11,400 m)
* Rate of climb: 2,600 ft/min (12.7 m/s)
* Wing loading: 53.4 lb/ft² (260 kg/m²)
* Power/mass: 0.06 hp/lb (0.09 kW/kg)

Armament

* Guns: 6 × 37 mm (1.46 in) M4 cannons (never installed in prototype)