As a contender in the 1937 US Navy shipboard single-seat fighter competition, the Seversky-designated NF-1 (Naval Fighter No 1) was derived from the basic P-35. Wssentially a P-35 with a Cyclone instead of P&W R-1830, arrestor hook, bomb racks, and AP-1’s rearward-retracting gear.
The design was flown for the first time on 3 May 1937 piloted by C H Miller, registered NX1254. Powered by a Wright R-1820-22 Cyclone nine-cylinder radial rated at 950hp for take-off and having provision for one 7.62mm and one 12.7mm gun in the forward fuselage, the NF-1 was delivered to Anacostia NAS for evaluation under the US Navy designation XFN-1 on 24 September 1937 on some USN records as A8978. This designation was actually applied for “book-keeping purposes”, no Navy contract being issued.
The NF-1 had initially flown with a vertical windscreen similar to that first fitted to the AP-1, but this had been replaced by a more conventional windscreen prior to delivery to Anacostia. At an early phase in the evaluation the fairings attached to the main oleo legs, which fully enclosed the undercarriage when retracted, were removed.
By consensus, the XFN-1 lacked the low-speed handling characteristics demanded for shipboard operation and the fighter was rejected by the Navy, further development being discontinued.
Engine: Wright R-1820-22 Cyclone, 950hp
Wingspan: 10.97 m / 36 ft 0 in
Wing area: 20.44 sq.m / 220.01 sq ft
Length: 7.44 m / 24 ft 5 in
Height: 2.77 m / 9 ft 1 in
Max take-off weight: 2373 kg / 5232 lb
Empty weight: 1823 kg / 4019 lb
Max. speed: 430 km/h / 267 mph
Stall: 69 mph
Range: 1570 km / 976 miles
Ceiling: 30,700’
seats: 1
All Aero 