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[edit] Specifications (Whirlwind)
General characteristics
Crew: One pilot
Length: 32 ft 3 in (9.83 m)
Wingspan: 45 ft 0 in (13.72 m)
Height: 11 ft 7 in (3.53 m)
Wing area: 250 ft² (23 m²)
Empty weight: 8,310 lb (3,770 kg)
Loaded weight: 10,356 lb (4,697 kg)
Max takeoff weight: 11,410 lb (5,175 kg)
Performance
Maximum speed: 360 mph (560 km/h)
Range: 808 miles (1,300 km)
Service ceiling 30,315 ft (9,240 m)
Rate of climb: 1.550 ft/min (474 m/min)
Wing loading: 41 lb/ft² (204 kg/m²)
Armament
4x Hispano 20 mm cannon in nose (60 rounds per gun, 240 rounds total)
2x 250 lb (115 kg) or 500 lb (230 kg) bombs
The Whirlwind's origin lay in the new aircraft being developed for the RAF after the last of the biplane fighters. With higher attack speeds giving shorter opportunities for firing on targets, it was decided to increase the minimum level of armament on their aircraft. Instead of two rifle calibre machine guns, eight were specified. At the same time it was recognised that guns such as the Hispano-Suiza with 20 mm exploding ammmunition offered another route to heavy firepower and requests were made for aircraft designs with four of these cannon.
A serious problem for air planners of the 1930s was that one could build a nimble combat aircraft only if it was small. Such an aircraft would have limited space for fuel, and would only have enough range to fight in defensive operations. A multi-engined fighter appeared to be the best solution to the problem of range, but it seemed that any fighter large enough to incorporate a substantial fuel load would be too unwieldy to fight its single-engine counterparts.
The Germans and U.S. pressed ahead with such programs anyway, resulting in the Messerschmitt Bf 110 and the Lockheed P-38. Soon the Luftwaffe was boasting that the 110 could beat any single-engine fighter, and do so, while operating at long ranges escorting their bombers. This piqued the interest of the Air Ministry who finally decided to try their hand at such a "destroyer" design and sent out a requirement to aircraft manufacturers. Gloster, Hawker and Westland all responded; the Gloster F.9/37 and Westland F.37/35 designs (from an earlier specification issued for a cannon-armed fighter) were given the go-ahead (Hawker was busy with the Hurricane).
Westland Whirlwind prototype L6845 c.1940Westland's design team, under the new leadership of Teddy Petter (who later designed the English Electric Canberra and Lightning), returned an aircraft that employed state-of-the-art technology. The fuselage was a small tube with a T-tail at the end, built completely of stressed-skin monocoque duraluminium. The pilot sat high under one of the world's first full bubble canopies, and the low and forward location of the wing made for superb visibility (except directly over the nose). In the nose were four 20 mm cannons, making it the most heavily armed fighter aircraft of its era with their clustering meaning there were no convergence problems as there are with wing-mounted guns.
The resulting design was quite small, only slightly larger than the Hurricane in overall size, but smaller in terms of frontal area. All of the wheels fully retracted and the entire aircraft was very "clean" with few openings or protuberances. Careful attention to streamlining and two 885 hp Peregrine engines powered it to over 360 mph (580 km/h), the same speed as the latest single-engine fighters, using much higher-powered engines. The speed quickly garnered it the nick-name Crikey, (a minced oath meaning "my god!" or more accurately "Christ's keys!").
The first prototype (L6844) flew on 11 October 1938 with production starting early the next year. It exhibited excellent handling and was very easy to fly at all speeds. The only exception was landing, which was all too fast. Fowler flaps were added to correct this problem, which also required the horizontal stabilizer (tailplane) to be moved up, out of the way of the disturbed air flow when the flaps were down. Hopes were so high for the design that it remained "top secret" for much of its development, although it had already been mentioned in the French press.
