Air Ministry Specification F.18/37 was concerned with the design and development of two advanced interceptor fighters: one with a Rolls-Royce Vulture engine was identified initially as the R (Rolls-Royce) type fighter; the second, with a Napier Sabre engine, was known as the N (Napier) type. Prototypes of both were built, the first designated as the Hawker Tornado, but development problems with the Vulture caused this programme to be abandoned.
The Sabre-engined N-type fighter prototype flew for the first time on 24 February 1940, but after the collapse of France in June was stopped to enable Hawker to devote its maximum effort to the production of the Hurricane. This caused considerable delay in the introduction of the
Typhoon, work on which was not resumed until later in 1940. The first production Typhoon flew on 26 May 1941. This was, in profile, a very Hurricane-looking low-wing monoplane, with retractable tailwheel-type landing gear. Construction combined what had become traditional Hawker with stressed-skin techniques. The one very un-Hurricane-like feature was the chin-fairing for the ventral radiator.
Typhoon IA production aircraft began to enter RAF service in September 1941, and went into action in the summer of 1942. Initial usage proved a great disappointment, with unsatisfactory high-altitude performance, inferior rate of climb
and frequent engine breakdowns. When structural failure of the tail unit caused a number of fatal accidents it was suggested that the Typhoon should be withdrawn from service. Fortunately its superb low-level performance ensured that fast action was taken to overcome the shortcomings, and introduction of the Sabre II engine brought improved reliability.
Typhoon I A were armed with 12 x 7.7mm Browning machine-guns, but the bomb-dropping, cannon-firing or rocket-firing Typhoon IB became 'train-busters' and, with the invasion of Europe, proved to be a valuable component of the 2nd Tactical Air Force. Utilised on a 'cab-rank' system, under which Typhoons on standing patrol could be called in from the ground for tactical close support of army formations, they decimated the enemy's Panzer divisions. Indeed, the Typhoon's fire-power was sometimes compared with that of a broadside from a cruiser, and was sufficient to penetrate the most heavily armoured tanks.
A total of 3,330 Typhoons were produced for the RAF, but by the end of 1945 none remained in front-line service.
