Curtiss XP-46

A United States Army Air Corps (USAAC) specification based upon a Curtiss proposal was the basis for an order placed in September 1939 for the XP-46. The requirements called for a single-engine, low-wing aircraft, slightly smaller than the P-40, and with a wide-track, inward-retracting landing gear. The selected powerplant was a 1,150 hp (858 kW) Allison V-1710-39 V-12 engine. The planned armament included two .50 in (12.7 mm) synchronized machine guns in the forward fuselage and provisions for eight .30 in (7.62 mm) wing-mounted guns. The USAAC later added requirements for self-sealing fuel tanks and 65 lb (29 kg) of armor, the weights of which adversely affected performance.

In 1940 the British Purchasing Commission placed an order for the P-46 as a replacement for the P-40,^[1] the British service name 'Kittyhawk' was allocated by the Air Ministry in anticipation of receiving the aircraft.^[2]

However, the USAAC asked Curtiss in July 1940 – while the XP-46 prototypes were under construction – to prioritize an upgraded P-40, featuring the engine intended for the XP-46. This would also avoid disruptions to the production line caused by any switch to a new airframe. The British order for the P-46 was later cancelled,^[1] and the 'Kittyhawk' name subsequently applied to the upgraded P-40.

Two prototypes, designated XP-46A, were nevertheless delivered to the USAAC; the first flight occurred on 15 February 1941. The type's performance during trials was found to be inferior to the then-contemporary P-40D. As the P-46 offered no significant improvement on the P-40, the program was cancelled.^[3]

A myth claims that work on the XP-46 was the basis of the North American NA-73X – the prototype P-51 Mustang. While North American Aviation (NAA) purchased technical aerodynamic data on the P-40 and XP-46 from Curtiss for $56,000, and there are certain design similarities in the radiator/oil-cooler configuration of the two types, North American had already made significant progress on its design.^[4][a]

Data from Curtiss Aircraft 1907–1947^[6]

General characteristics

• Crew: 1
• Length: 30 ft 2 in (9.19 m)
• Wingspan: 34 ft 3.75 in (10.4585 m)
• Height: 10 ft 1 in (3.07 m)
• Wing area: 208 sq ft (19.3 m²)
• Airfoil: root: NACA 23016.5; tip: NACA 23009^[7]
• Empty weight: 5,625 lb (2,551 kg)
• Gross weight: 7,665 lb (3,477 kg)
• Powerplant: 1 × Allison V-1710-39 V-12 liquid-cooled piston engine, 1,150 hp (860 kW)
• Propellers: 3-bladed constant-speed propeller

Performance

• Maximum speed: 355 mph (571 km/h, 308 kn) at 12,200 ft (3,700 m)
• Range: 325 mi (523 km, 282 nmi)
• Time to altitude: 12,300 ft (3,700 m) in 5 minutes

Armament

• Guns:
  
  • 2 × 0.50 in (13 mm) synchronized machine guns in the forward fuselage
  • Provision for 8 × 0.30 in (7.6 mm) wing-mounted guns

• Curtiss P-40
• Curtiss XP-42 - an earlier design also intended to replace the P-40, but not put into production
• North American P-51 Mustang
• Curtiss P-60 – a series of designs developed from the XP-46