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 millimeter 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.
TEMPEST MARK V:
| spec | metric | english |
|---|---|---|
| wingspan | 12.5 m | 41 ft |
| length | 10.3 m | 33 ft 8 in |
| height | 4.9 m | 16 ft 1 in |
| empty weight | 4,080 kg | 9,000 lb |
| max loaded weight | 6,140 kg | 13,540 lb |
| maximum speed | 686 km/h | 426 mi/h / 370 kn |
| service ceiling | 11,125 m | 36,500 ft |
| range | 2,460 km | 1,530 mi / 1,330 nmi |
The jump from Tempest Mark I to Tempest Mark V begs the question of what happened to Marks II, III, and IV. Mark II was a Centaurus-powered Tempest, and as will be explained in the next section, it did reach production. Marks III and IV were to be powered by different variants of the Rolls-Royce Griffon V-12 engine. One Mark III was actually built, though as will be described not as a Tempest, and the Mark IV was cancelled.
The Tempest V was in the hands of operational squadrons by April 1944, where it profitably carried on in the low-level attack tradition of the Typhoon, which it was replacing as Tempest production increased. However, in June 1944, the first German V-1ss were launched against London, and the Tempest's excellent low-altitude performance made it one of the preferred tools for dealing with the fast-flying little missiles. Tempest squadrons racked up a considerable percentage of the total RAF kills of the flying bombs.
In the meantime, the Tempest continued strikes in support of Western armies advancing across Europe, and engaged Luftwaffe aircraft when they could be found. Tempests circling Luftwaffe airfields also scored a number of kills on new German jets such as the Messerschmitt Me 262, which was helpless on landing approach as its jet engines could not spool up quickly.
While Hawker was working towared the introduction of the Tempest V, Sydney Camm and his crew were also revisiting the Centaurus radial engine, incorporating it into two other Tempest prototypes.
The first Centaurus Tempest, or "Tempest Mark II", flew on 28 June 1943 with a Centaurus IV, and was followed presently by the second. The radial engine installation owed much to examinations of a captured Focke-Wulf FW-190, and was unprecedentedly clean and effective. There were problems with vibration, but they were fixed by addition of six rubber shock mounts.
The Centaurus was generally regarded as superior to the Sabre, particularly in terms of reliability, and the Centaurus engine and Tempest airframe proved an excellent match. The combination looked so promising that a contract for 500 of the type was placed as far back as September 1942, but Gloster was overloaded with production of the Typhoon and development of the Gloster Meteor, and there was no way the company could handle the additional load.
Tempest Mark II production ended up in the hands of Bristol, and the switch delayed production even more. The first Tempest II was rolled off the line on 4 October 1944, but then production was shifted back to Hawker.
A total of 452 Tempest IIs were built, including 136 basic Mark IIs and 316 "Fighter Bomber Mark IIs" (FB.II). They were built mostly by Hawker and generally with Centaurus V engines, and of that number 300 were completed after the war. The Tempest II, despite its slightly improved performance and better reliability, never saw combat. Tempest IIs produced during the war were intended for combat against the Japanese, but the Pacific War ended before they could be deployed.
89 Tempest FB.IIs were passed on from the RAF to the Indian Air Force in 1947, while another 24 were passed on to the Pakistani Air Force.
Various engineering refinements that had gone into the Tempest II were incorporated into the last Tempest variant, the "Tempest VI", which was fitted with a Sabre V engine with 2,340 horsepower. Hundreds of Tempest VIs were ordered, though only 142 were built. The last piston engine fighter in RAF service was a Tempest VI, which was in use as a target tug when it was retired in 1953.
This article is based on the "The Hawker Typhoon, Tempest, & Sea Fury" version 1.1, by Greg Goebel. The original version (placed in the public
domain) can be accessed at: http://www.vectorsite.net/avcfury.html .Tempest in combat / Tempest II & VI