The twin-engined Whirlwind showed much potential with its performance and heavy armament. The type would suffer through delays in its production that meant other aircraft entered service
before the Westland Whirlwind and served in the roles it had been intended for the aircraft to do.
Responding to Air Ministry Specification F/37.35 which was issued in 1935 requesting a single-seater fighter with an armament of four cannons for both day and night duties Westland
submitted their Whirlwind design with the prototype flying for the first time on the 11th October 1938. It was announced during January the following year that a contract for 200 aircraft
had been won.
The Westland Whirlwind Mk I was powered by a pair of 885-hp Rolls-Royce Peregrine engines giving the aircraft a top speed of 387 mph, range of 1,200 miles and a service ceiling of 44,000 ft.
Armament was four 20mm cannons. The new aircraft, which would be the first twin-engined fighter of the Royal Air Force, looked promising. Its firepower at the time was better than any other fighter
in the world as was its low-altitude performance and No. 25 Squadron, RAF North Weald would receive the first two production aircraft before they were re-equipped with the
Production versions of the aircraft began to reach No. 263 Squadron based at RAF Drem on the 6th July 1940 as they began the task of eliminating bugs in both the airframe and Rolls-Royce Peregrine
engines. No. 263 Squadron used the Whirlwind alongside their Hawker Hurricanes and after moving to RAF Exeter
became operational with the aircraft on the 7th December 1940. They would have their remaining Hurricanes replaced, and on the 20th January 1941 would become the first squadron to
only operate the Whirlwind. The squadron would claim its first success on the 8th February 1941 when an Arado Ar 196 was shot down despite troubles with its cannon armament.
Due to a shortage of engines deliveries of the Whirlwind were slow with the Royal Air Force receiving only eight of the type by the close of 1940, in fact only one other squadron would be equipped
with the Whirlwind. This was No. 137 Squadron which was formed on the 20th September 1941 at RAF Charmy Down.
Despite the positive performance and armament of the aircraft its dogfighting abilities at higher altitude was called into question and it could only be used at a limited number of
airfields due to its high landing speed leading to a second order that had been placed for 200 more aircraft to be cancelled and the initial contract for 200 aircraft cut to just 112.
Another thing against the Whirlwind was that by 1940 the Supermarine Spitfire was being tested with 20mm cannons before they were introduced on the Spitfire Mk II, and so by the end of
1943 the Whirlwind had been replaced by the Hawker Hurricane which re-equipped No. 137 Squadron with Hawker Typhoons re-equipping No. 263 Squadron.
A second prototype, equipped with twelve 0.303-in machine-guns, and a third equipped with a 37-mm cannon were sent to No. 25 Squadron, who at that time were using the Bristol Blenheim,
for night-fighter trials although the Whirlwinds production delays saw the Bristol Beaufighter enter service in this role instead.
January 1942 would see the last of the 116 Westland Whirlwinds leave the production line.