The only Westland fighter to achieve operational status with the RAF, the Whirlwind was designed in response to Specification F.37/35 for a “cannon fighter” armed with four 20mm guns. As the P.9, the Westland design emerged as a low-wing monoplane with two Rolls-Royce Peregrine I 12-cylinder liquid-cooled Vee engines, each rated at 885hp at 4575m. The four Hispano Mk I guns were grouped in the nose, the pilot enjoyed a good all-round view from a fully-enclosed cockpit in line with the wing trailing edge, and radiators were buried in the wing leading edges inboard of the nacelles. Construction was of metal throughout, with flush-riveted stressed skins, a novelty being the use of magnesium rather than aluminium sheet to cover the monocoque fuselage aft of the cockpit.
Two prototypes were ordered by the Air Ministry in February 1937, and the first of these flew on 11 October 1938. Despite delays in development and production of the Peregrine engine, two contracts were placed in 1939, each for 200 fighters as Whirlwind Is, and the first series aircraft (P6966) flew in June 1940.
In the event, production ended with 114 aircraft built, these serving with only two RAF squadrons (Nos 263 and 137). Armament problems and changing operational needs curtailed the usefulness of the Whirlwind, which was enhanced in late 1942 by the addition of a pair of wing racks to carry two 113kg or 227kg bombs. Operational use of the Westland fighter came to an end in November 1943.
Replica: Butterworth Westland Whirlwind
Whirlwind I
Engines: 2 x Rolls Royce Peregrine I, 873 hp
Wingspan: 13.72 m / 45 ft 0 in
Wing area: 23.22 sq.m / 249.94 sq ft
Length: 9.83 m / 32 ft 3 in
Height: 3.20 m / 11 ft 6 in
Empty weight: 3699 kg / 7840 lb
Max take-off weight: 4658 kg / 10,270 lb
Max. speed: 313 kts / 579 km/h / 360 mph
Landing speed: 80 mph
ROC: 3000 fpm / 915 m/min
Ceiling: 9150 m / 30000 ft
Range: 1287 km / 800 miles
Crew: 1
Armament: 4x 20mm Hispano Mk.1 MG, 60 rds each
Whirlwind IA
Engines: 2 x Rolls Royce Peregrine I, 873 hp
Wingspan: 13.72 m / 45 ft 0 in
Wing area: 23.22 sq.m / 249.94 sq ft
Length: 9.83 m / 32 ft 3 in
Height: 3.20 m / 11 ft 6 in
Max take-off weight: 5165 kg / 11387 lb
Empty weight: 3770 kg / 8311 lb
Max. speed: 313 kts / 579 km/h / 360 mph
Landing speed: 80 mph
Ceiling: 9150 m / 30000 ft
Range: 1287 km / 800 miles
Crew: 1
Armament: 4x 20mm MG
Bombload: 454kg
All Aero 