Tempest Mk I
The development of the Hawker Tempest I was abandoned primarily due to production difficulties and delays with its intended engine, the Napier Sabre IV, and the earlier availability and success of the less challenging Tempest V.
The Tempest I, with prototype HM599, was designed to be powered by the Napier Sabre IV engine. However, “production difficulties arose with the engine,” leading to the abandonment of the Tempest I development. The Sabre IV had been experiencing severe problems that cast doubt on the viability of future projects relying on it. Mk I fell victim to wartime planning exigencies, leading to the abandonment of further work on what was considered “potentially the best Tempest variant”. This implies a strategic decision to streamline production efforts.
The Tempest V, powered by the Sabre II engine, was ready to fly much earlier (its prototype HM595 flew on 2 September 1942, before the Tempest I prototype) due to delays with other engine variants and necessary redesigns for Griffon installations. Its subsequent “success and earlier availability” made the continued development of the Tempest I less critical. Production contracts for 400 Tempest Is were initially issued in August 1942, but this program was later transferred to the Tempest V due to the aforementioned delays and difficulties with the Sabre IV.
While the Tempest I prototype (HM599) achieved a high top speed of 466 mph at 24,500 feet, this performance was specific to certain gear at relatively high altitudes, and the engine issues ultimately halted its progress.