Hawker Tempest

The Hawker Tempest was a Royal Air Force (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.

Development

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 at that time in the form of the Hawker P. 1012 (or Typhoon II). 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 that the Americans had used 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 thickness was further back towards the middle of the chord. The new wing was originally longer than that of the Typhoon at 43 ft (13.1 m), but the wingtips were clipped and the wing became shorter than that of the Typhoon at 41 ft (12.5 m).

The new wing cramped the fit of the four Hispano 20 mm cannon that were being designed into the Typhoon. They had to be moved back further into the wing, and the wing was extended into an elliptical shape to accommodate the cannons and the 800 rounds of ammunition. 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—giving a maximum of 360 gallons and an operational radius of 500 miles, almost double that of the Spitfire IX.

The undercarriage was both longer and had a wider spread (16 feet) to improve stability at the high landing speed of 110 mph (180 km/h) and to allow for a new four-blade propeller of almost 12 feet in diameter. The main gear also needed new thin tyres in order to fit within the wing.

The new design was basically solid by October 1941 and the Air Ministry issued specification F.10/41 that had been written to fit the aircraft. 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 problems experienced with delivery of engines led the Air Ministry to ask for six prototypes with different engines so that if the a delay hit one engine an alternative would be available. This gave the Mk I (aircraft HM599) with a Sabre IV, two Mk IIs (LA602 and LA607) with the Centaurus IV, MK III (LA610) with a Griffon IIB, Mk IV (LA614) with a Griffon 61 and the Mk V (HM595) with the Sabre II.

The first Tempest prototype, the Mark V, flew on 2 September 1942. This aircraft was really just a Typhoon fitted with the new elliptical wing and retained the Typhoon's frame canopy, automobile-style door, the Sabre II engine, and "beard" radiator. It was quickly fitted with a bubble canopy like the later Typhoons and a modified vertical tailplane that almost doubled the control surface area.

Test pilots found the Tempest a great improvement over the Typhoon in performance, although it was "pretty tricky to fly". 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 "Tempest Mark I" with the Sabre IV did not fly until 24 February 1943. This prototype also had at first the older Typhoon cockpit and vertical tailplane. 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 mph).

Only one Mark I was built. With the Sabre IV unavailable, Camm simply went into production with the Sabre II engined "Tempest V". The first rolled off the production line on 21 June 1943. The first 100 Tempest Vs delivered had the long-barrelled Mark II 20 mm Hispano cannon, and such aircraft were referred to as "Tempest V Series I". Later production, providing a total of 800 aircraft known as "Tempest V Series II", used the short-barrelled Mark V Hispano cannon, eliminating the protruding barrels - though these had not been as prominent as on the Typhoon.

Tempest Mark V

In his book The Big Show, French ace Pierre Clostermann, who flew Mk. Vs with Nos. 274 and 3 squadrons of the RAF in 1944-45, quotes much higher top speed figures: 780 km/h (485 mph / 421 kts) at maximum rated power (2,850 hp) and 820 km/h (510 mph / 443 kts) on emergency power (3,040 hp). These figures, though plausible, seem somewhat optimistic given the fact that the holder of the official world speed record for a propeller-driven aircraft, a modified Grumman Bearcat named the Rare Bear, needed more than 4,000 hp to reach 850 km/h (528 mph / 459 kts) in 1989.

The jump from Tempest Mark I to Tempest Mark V raises 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 prototype was built with a Griffon 85 engine it would later be modified to become the prototype Hawker Fury. The Mark IV prototype was cancelled in 1943.

Tempest V in combat

The Tempest V was in the hands of operational squadrons by April 1944 (No. 3 and No. 56 Squadrons based at RAF Newchurch, Kent), where it profitably carried on in the low-level attack tradition of the Typhoon, which it was replacing as Tempest production increased. In June 1944, however, the first German V-1 flying bombs were launched against London and the Tempest's excellent low-altitude performance made it one of the preferred tools for dealing with the small fast-flying unmanned missiles. Tempest squadrons racked up a considerable percentage of the total RAF kills of the flying bombs (638 of a total of 1,846 destroyed by aircraft).

Early Tempests suffered numerous engine problems mainly due to the 150 octane fuel being inadequate. There were also problems with the induction system, the lubricating system, and the carburettor air intake (a simple backfire could lead to an explosion).

The Tempest was also deployed in support of the Allied armies advancing across northern Europe and engaged Luftwaffe aircraft when they could be found. The Tempest force was part of 122 Wing based at Volkel airfield near Uden, Holland. It comprised of No. 486 (RNZAF, the only non-RAF force to be equipped with the Tempest), 80, 56, and 274 Squadrons. In the first month of operations (December 1944) 52 German fighters were downed and 89 locomotives destroyed for the lost of 20 Tempests. Following the surprise Luftwaffe raids of January 1, 1945 (Operation Bodenplatte), 122 Wing bore the brunt of fighter operations for the 2nd Tactical Air Force, and came under intense pressure, losing forty-seven pilots that month.

Tempests also scored a number of kills against the new German jets such as the Messerschmitt Me 262, mainly by using the "rat code". Tempests on immediate alert took off when a Luftwaffe jet-aircraft was reported crossing the Rhine. They were not directed to intercept the jet but instead flew to patrol the airfield group (Rheine-Hopsten) from which the jet originated. The aim was to attack the enemy aircraft on its approach to land, when it was at its most vulnerable - travelling slowly, with flaps down and where its slow acceleration would tell against it. The Germans responded by creating a "flak lane" of over 150 quadruple 20 mm guns to protect the landing approaches. After seven Tempests were lost in a single week trying to attack "rats" in the flak lane, the "rat code" was discontinued.

Top scoring Tempest pilot was Squadron Leader D.C. Fairbanks DFC. Fairbanks, an American, (the son of a Cornell Professor) joined the RCAF in 1941. By mid 1944 he was flying with 274 Squadron. By the time he was shot down and made a POW in February 1945 he had destroyed 12 German aircraft (and 1 shared) to make him the highest scoring Tempest ace.

"The Messerschmitt Me 262's most dangerous opponent was the British Hawker Tempest — extremely fast at low altitudes, highly-manoeuvrable and heavily-armed." — Hubert Lange, Me 262 pilot.

Tempest II

While Hawker was working toward the introduction of the Tempest V, Sydney Camm and his crew were also revisiting the Bristol Centaurus radial engine, incorporating it into two other Tempest prototypes.

The first Centaurus powered Tempest, the "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, and would have formed part of "Tiger Force" 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.

Tempest VI

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 (1,700 kW). Hundreds of Tempest VIs were ordered, though only 142 were built. The last piston-engined fighter in RAF service was a Tempest VI. It and one other VI along with a number of Vs had been converted to target tugs and this was its role when it was retired in 1953.

Operators

India, New Zealand, Pakistan, United Kingdom, Canada.

Specifications (Tempest V)

References

Reed/Beamont - Typhoon & Tempest at War - Ian Allen - ISBN 0-7110-0542-7
This article is based on "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 .
Hubert Lange quote from http://www.hawkertempest.se/

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