The Hawker Tempest was a RAF fighter aircraft of World War II, an improved derivative of the Hawker Typhoon, and one of the most powerful fighters used in the war.
While Hawker and the RAF were struggling to turn the Typhoon into a useful aircraft, Hawker’s Sidney Camm and his team were rethinking the design. The Typhoon’s thick, rugged wing was partly to blame for some of the aircraft’s performance problems, and as far back as March 1940 a few engineers had been set aside to investigate the new “laminar flow” wing, which the Americans had implemented in the P-51 Mustang.
The laminar flow wing had a maximum chord, or ratio of thickness to length of the wing cross section, of 14.5 %, in comparison to 18 % for the Typhoon. The maximum chord was also moved back towards the middle of the cross section. The new wing was originally longer than that of the Typhoon, at 13.1 m (43 ft), but then the wingtips were clipped off and the wing became shorter than that of the Typhoon, at 12.5 m (41 ft).
The new wing cramped the fit of the four Hispano 20 mm cannon that were being designed into the Typhoon. The cannon were moved back further into the wing, and the wing was extended into an elliptical shape to accommodate the cannon. The new elliptical wing had greater area than the Typhoon’s. Camm, who was noted for a sharp sense of humor, later remarked: “The Air Staff wouldn’t buy anything that didn’t look like a Spitfire.”
Another important feature of the new wing was that radiators for the new Napier Sabre IV engine were fitted into the leading edge of the wing inboard of the landing gear. This eliminated the distinctive “beard” radiator associated with the Typhoon and improved aerodynamics, but also displaced fuel tanks that had been fitted into the leading edge of the Typhoon’s wing at the same location.
This greatly reduced fuel capacity, but Hawker engineers found they could stretch the fuselage 53 cm (21 in) ahead of the cockpit to accommodate more fuel storage in the fuselage. The longer nose did not seriously impair the pilot’s forward view, but the vertical tailplane had to be extended.
The new design was basically solid by October 1941, and the Air Ministry issued a specification designated “F.10/41” that had been written to fit. A contract for two initial prototypes was issued the next month. The aircraft was originally named the “Typhoon Mark II”, but was renamed “Tempest” in January 1942, when more prototypes with various experimental configurations were ordered.
The first Tempest prototype flew on 2 September 1942. This aircraft was really just a Typhoon fitted with the new elliptical wing, and retained the Tiffy’s frame canopy, automobile doors, and Sabre II engine. It was quickly fitted with a bubble canopy and taller vertical tailplane.
Test pilots found the Tempest a great improvement over the Typhoon. The Air Ministry had already ordered 400 Tempests in August, but production of the new Sabre IV engine ran into protracted problems and delays. The second prototype, the first with the Sabre IV and designated “Tempest Mark I”, did not fly until 24 February 1943. This prototype also had the older Typhoon cockpit and vertical tailplane at first. Elimination of the “beard” radiator did much to improve performance, and the Tempest Mark I was the fastest thing Hawker had built to that time, attaining a speed of 750 km/h (466 mi/h).
Only one Mark I was built. Sabre IVs were still unavailable, so Camm simply went into production using the Sabre II. The first “Tempest V”, as this variant was known, rolled off the production line on 21 June 1943. The first 100 Tempest Vs delivered had the long-barrelled Mark II 20 millimeter Hispano cannon, and such aircraft were referred to as “Tempest V Series 1”. Later production, providing a total of 800 aircraft known simply as “Tempest V”, used the short-barrelled Mark V Hispano cannon, eliminating the protruding barrels that had been a trademark of the Typhoon.