Hawker Tempest

The Hawker Tempest was a British fighter aircraft primarily used by the Royal Air Force (RAF) in the Second World War. The Tempest was an improved derivative of the Hawker Typhoon, and one of the most powerful fighter aircraft used during the war.

Origins
During development of the Typhoon the design team, under the leadership of Sydney Camm, were already planning design improvements, this process resulting in the Hawker P. 1012 (or Typhoon II). Although the Typhoon was basically a good design, Camm and his design team were disappointed with the wing which proved to be too thick in its cross section; this created airflow problems and inhibited flight performance, especially at higher altitudes. The Typhoon's wing, using a NACA 4 digit series wing section, had a maximum thickness to chord ratio of 19.5% (root) to 12% (tip). In March 1940, engineers were assigned to investigate the new low drag laminar flow wing developed by NACA in the United States, which had been used in the new North American P-51 Mustang. A laminar flow wing adopted for the Tempest series had a maximum thickness to chord ratio of 14.5% at the root, tapering to 10% at the tip. The maximum thickness of the Tempest wing was set further back at 37.5% of the chord versus 30% for the Typhoon's wing.

The wingspan was originally greater than that of the Typhoon at 43 ft (13.1 m), but the wingtips were later "clipped" and the wing became shorter; 41 ft (12.5 m) versus 41 ft 7 in (12.7 m). The wing planform was changed to an elliptical shape to accommodate the 800 rounds of ammunition for the four 20 mm (.79 in) Hispano cannons, which were moved back further into the wing. The new elliptical wing had greater area than the Typhoon's. However, the new wing design sacrificed the leading edge fuel tanks of the Typhoon: to make up for this loss in capacity, Hawker engineers added a new 21 in (53 cm) fuel bay in front of the cockpit, with a 76 gal (345 l) fuel tank. In addition, two inter-spar wing tanks, each of 28 gal (127 l), were fitted on either side of the centre-section and, starting with late model Tempest Vs, a 30 gal (136 l) tank was carried in the leading edge of the port wingroot, giving the Tempest a total internal fuel capacity of 162 gal (736 l).

In service, Tempests also carried two specially designed, streamlined, drop tanks of 45 gal (204 l) giving a maximum of 360 gal (1,636 l) and an operational radius of 500 mi (805 km) Another important feature of the new wing was Camm's proposal that radiators for the new Napier Sabre IV engine were to be fitted into the leading edge of the wing inboard of the undercarriage. This eliminated the distinctive "chin" radiator associated with the Typhoon and improved aerodynamics. A further improvement of the Tempest wing over that of the Typhoon was the exceptional, flush riveted surface finish, essential on a high performance laminar flow airfoil. Fortunately for the pilots, the new wing and airfoil, and the four-bladed propeller unit, eliminated the high frequency vibrations that had plagued the Typhoon.



The redesigned main undercarriage legs were longer and had a wider track (16 ft/5 m) to improve stability at the high landing speed of 110 mph (180 km/h), and to allow tip clearance for a new de Havilland 14 ft (4 m) diameter four-blade propeller. The main undercarriage units were Dowty levered suspension units incorporating trunnions which shortened the legs as they retracted. The majority of the Tempests built used 30 by 9 inch (76.2 by 22.9 cm) four-spoke wheels, while the prototypes and early production Tempest Vs used the Typhoon's larger 34 by 11 inch (83.4 by 28 cm) five-spoke wheels. The retractable tailwheel was fully enclosed by small doors and could be fitted with either a plain Dunlop manufactured tyre, or a Dunlop-Marstrand "twin-contact" anti-shimmy tyre.

Camm and the Hawker design team placed a high priority on making their aircraft easily accessible to both air and ground crews; to this end the forward fuselage and cockpit areas of the earlier Hurricane and the Tempest and Typhoon families were covered by large removable panels providing access to as many components as possible, including flight controls and engine accessories. Both upper wing roots incorporated panels of non-slip coating. For the pilot a retractable foot stirrup under the starboard root trailing edge was linked to a pair of handholds which were covered by spring-loaded flaps. Through a system of linkages, when the canopy was open the stirrup was lowered and the flaps opened, providing easy access to the cockpit. As the canopy was closed the stirrup was raised into the fuselage and the flaps snapped shut.

Prototypes
The new design was finalised by October 1941 and the Air Ministry issued specification F.10/41 that had been written to fit the aircraft. A contract for two prototypes of the "Typhoon Mark II" was issued in November, and the new fighter was renamed "Tempest" in January 1942. The problems experienced with delivery of engines finally led the Air Ministry to ask for six prototypes with different engines so that if a delay hit one engine an alternative would be available. This resulted in a single Mk.I, HM599, with a Sabre IV, two Mk.IIs (LA602 and LA607) with the Centaurus IV, a Mk.III (LA610) with a Griffon IIB, a Mk.IV (LA614) with a Griffon 61, and the Mk.V (HM595) with the Sabre II.



The first Tempest prototype, the Mark V HM595, was first flown by Philip Lucas from Langley on 2 September 1942. This aircraft retained the Typhoon's framed canopy, car-style door, powered by a Sabre II engine, and fitted with the "chin" radiator, similar to that of the Typhoon. It was quickly fitted with the same bubble canopy fitted to Typhoons, and a modified fin that almost doubled the vertical tail surface area. The horizontal tailplanes and elevators were also increased in span and chord (these were also fitted to late production Typhoons.)

Test pilots found the Tempest a great improvement over the Typhoon in performance; in February 1943 the pilots from the A&AEE at Boscombe Down reported that they were impressed by "a manoeuvrable and pleasant aircraft to fly with no major handling faults". 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 structure and vertical tailplane. Elimination of the "chin" radiator did much to improve performance and the Tempest Mark I was the fastest aircraft Hawker had built to that time, attaining a speed of 466 mph (750 km/h). Continual problems with the Sabre IV meant that only one Mark I (HM599) was built; consequently, Hawker went into production with the Sabre II engined "Tempest V", with the first rolling off the production line on 21 June 1943.

Tempest Mark V
Even before the first flight of the prototype Tempest V a production order for 400 Tempests was placed by the Air Ministry.The order was split, with the initial batch of 100 being Tempest V "Series Is", powered by the 2,235 hp (1,491 kW), Napier Sabre IIA series engine with the chin radiator, while the rest would be the Tempest I with the Napier Sabre IV and leading-edge radiators. As it transpired the difficulties with the Sabre IV meant that this version never reached production and the order was switched to 300 Tempest V "Series 2"s. The first production Tempest V, JN729 was first flown by test pilot Bill Humble on 21 June 1943. Several of the early production aircraft underwent extensive service trials at Boscombe Down including clearances to be fitted with external stores, including 500 lb (227 kg) and 1,000 lb (454 kg) bombs and 3 in (76.2 mm) RP-3 rockets, although few Tempest Vs used such ordnance operationally during World War II.

Examination of captured Fw 190s brought about improvements in the windscreen/ side windows; by careful design and positioning of the frame structure blind spots were reduced to an absolute minimum. The three-piece windscreen had a bullet-resistant centre panel made up of two layers, the outer 1.5 in (38mm) thick and the inner 0.25 in (6.5 mm).

During production of the first batch of 100 Tempest V "Series Is", distinguished by their serial number prefix JNxxx, several improvements were progressively introduced and were used from the outset on all succeeding Tempest V "Series 2s", with serial number prefixes EJ, NV and SN. The rear fuselage fuselage/empennage joint originally featured 20 external reinforcing "fishplates", similar to those fitted to the Typhoon, but it was not long before the rear fuselage was strengthened and, with the fishplates no longer being needed, the rear fuselage became detachable. The first series of Tempest Vs used a built-up rear spar pick-up/bulkhead assembly (just behind the cockpit) which was adapted from the Typhoon. Small blisters on the upper rear wing root fairing covered the securing bolts. This was later changed to a new forged, lightweight assembly which connected to new spar booms: the upper wing root blisters were replaced by small "teardrop" fairings under the wings. The new spar structure also allowed the wings to carry up to 2,000 lb (907 kg) of external stores. Also developed specifically for the Tempest by Hawker was a streamlined 45 gal (205 l) "drop tank" and carrier fairing; the redesigned wing incorporated the plumbing for these tanks, one to each wing. The ailerons were fitted with spring-loaded tabs which lightened the aerodynamic loads, making them easier for the pilot to use and dramatically improving the roll rate above 250 mph (402 km/h). Starting with EJxxx series Tempest Vs the improved Sabre IIB and IIC were used, both of which were capable of producing over 2,400 hp (1,789 kW) on emergency boost for short periods of time. All versions of the Sabre drove four-bladed, 14 ft (4.267 m) diameter de Havilland Hydromatic or Rotol propellers.

The first 100 Tempest Vs used long-barrelled 20 mm (.79 in) Hispano Mk.IIs the barrels of which projected ahead of the wing leading edges and were covered by short fairings, while later production Tempest Vs switched to the short-barrelled Hispano Mk.Vs the muzzles of which were flush with the leading edges. Finally, while early Tempest Vs used Typhoon style 34 by 11 inch (83.4 by 28 cm) five-spoke wheels, the majority used smaller 30 by 9 inch (76.2 by 22.9 cm) four-spoke wheels.

As in all mass-produced aircraft, there may have been some overlap of these features as new components became available. In mid to late 1944 other features were introduced to both the Typhoon and Tempest: A Rebecca transponder unit was fitted, with the associated aerial appearing under the portside centre section. A small, elongated oval static port appeared on the rear starboard fuselage, just above the red centre spot. This was apparently used to more accurately measure the aircraft's altitude. Unusually, in spite of the Tempest V being the RAF's best low to medium altitude fighter, it was not equipped with the new Mk IIC gyroscopic gunsight, an asset which was fitted in RAF Spitfires and Mustangs from mid-1944 and one which considerably improved the chances of shooting down opposing aircraft. Tempest pilots continued to use either the Type I Mk.III reflector gunsight, which projected the sighting graticule directly onto the windscreen, or the Mk.IIL until just after the Second World War, when the gyro gunsight was introduced in Tempest IIs.

Two Tempest Vs, EJ518 and NV768, were fitted with Napier Sabre Vs and experimented with several different Napier made annular radiators, with which they resembled Tempest IIs. This configuration proved to generate less drag than the standard "chin" radiator, contributing to an improvement in the maximum speed of some 11 to 14 mph. NV768 was later fitted with a ducted spinner, similar to that fitted to the Fw 190 V1.

Another experimental Tempest V was SN354, which was fitted with two Vickers 47 mm "P" guns, one under each wing in a long "pod".

Tempest Mk.II
The decision to drop the Hawker Tornado allowed Sydney Camm and his design team to transfer the alternative engine proposals for the Tornado to the more advanced Typhoon II (later to be renamed "Tempest"). As a result the Tempest was designed from the outset to use the Bristol Centaurus 18 cylinder radial engine as an alternative to the liquid cooled engines which were also proposed. Two Centaurus powered Tempest Mk II prototypes were to be built.

Apart from the new engine and cowling, the Tempest II prototypes were similar to early series Tempest Vs. The Centaurus engines were closely cowled and the exhaust stacks were grouped behind and on either side of the engine: behind these were air outlets with automatic sliding "gills". The carburettor air intakes were in the inner leading edges of both wings, with an oil cooler and air intake in the inner, starboard wing. The radial engine installation owed much to examinations of a captured Focke-Wulf Fw 190, and was clean and effective.

The first Tempest Mk.II, LA602, flew on 28 June 1943 powered by a Centaurus IV (2,520 hp/1,879 kW) driving a four-blade propeller. LA602 initially flew with a Typhoon-type fin and rudder unit. This was followed by the second, LA607, which was completed with the enlarged dorsal fin and first flew on 18 September 1943: LA607 was assigned to engine development. The first major problem experienced during the first few flights were serious engine vibrations, which were cured by replacing the rigid, eight-point engine mountings with six-point rubber-packed shock mounts. In a further attempt to alleviate engine vibration, the four blade propeller was replaced with a five blade unit; eventually, a finely balanced four bladed unit was settled on. Problems were also experienced with engine overheating, poor crankshaft lubrication, exhaust malfunctions and reduction-gear seizures. Because of these problems, and because of the decision to "tropicalise" all Tempest IIs for service in the South-East Asian theatre, production was delayed.

Orders had been placed as early as September 1942 for 500 Tempest Mk.IIs to be built by Gloster but in 1943, because of priority being given to the Typhoon, a production contract of 330 Tempest Mk.IIs was allocated instead to Bristol, while Hawker were to build 1,800. This switch delayed production even more. The first Tempest II was rolled off the line on 4 October 1944 and the first six production aircraft joined the two prototypes for extensive trials and tests. With the end of the Second World War in sight, orders for the Tempest II were trimmed or cancelled; after 50 Tempest IIs had been built at Bristol's Banwell facility, production was stopped and shifted back to Hawker, which built a total of 402, in two production batches of 100, which were built as fighters and 302 which were built as fighter-bombers (FB.Mk.II) with reinforced wings and wing racks capable of carrying bombs of up to 1,000 lbs.

Physically, the Tempest Mk.II was longer than the Tempest Mk.V (34 ft 5 in/10.5 m versus 33 ft 8 in/10.3 m) and 3 in (76 mm) lower. The weight of the heavier Centaurus engine (2,695 lb/1,222 kg versus 2,360 lb/1,070 kg) was offset by the absence of a heavy radiator unit, so that the Tempest II was only some 20 lb (9 kg) heavier overall. Performance was improved; maximum speed was 442 mph (711 km/h) at 15,200 ft (4,633 m) and climb rate to the same altitude took four and a half minutes compared with five minutes for the Tempest V. The service ceiling was increased to 37,500 ft (11,430 m) The majority of the production aircraft built were tropicalised, with an air filter and intake installed in the upper, forward fuselage, just behind the engine cowling, and the L-shaped pitot head under the outer port wing was replaced by a straight rod projecting from the port outer wing leading edge. All production aircraft were powered by a (2,590 hp/1,932 kW) Centaurus V driving a 12 ft 9 inch (3.89 m) diameter Rotol propeller.

Tempest Mk.IIs produced during the war were intended for combat against Japan, and would have formed part of a proposed British Commonwealth long range bomber force based on Okinawa, Tiger Force. The Pacific War ended before they could be deployed.

The RAF passed 89 Tempest FB IIs to the Indian Air Force in 1947, while another 24 were passed on to the Pakistani Air Force. Several of these aircraft remain in existence, with three under active restoration to fly in the United States and New Zealand.

Tempest Mk.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 Napier Sabre V engine with 2,340 hp (1,700 kW). The more powerful Sabre V required a bigger radiator which displaced the oil cooler and carburettor air intake from the radiator's centre. Air for the carburettor was drawn through intakes on the leading edge of the inner wings, with the oil cooler being fitted behind the radiator. Most Tempest VIs were tropicalised with an air filter fitted in a fairing on the lower centre section. Hundreds of Tempest VIs were ordered, though only 142 were built. The last piston-engined fighter in RAF service was a Tempest VI.

For a long time it was thought that there were Tempest VIs converted for target towing: none of the service histories of the aircraft show TT conversions and no supporting photographic evidence has been found.

Tempest Light Fighter
The final development of the Tempest was designed as an improved lightweight Tempest for use against the light and agile types of Japanese fighters in the Far East. Known initially as the "Tempest Light Fighter" the aircraft was later officially named the "Fury" and "Sea Fury".

Drawing board designs
In 1944, in response to F.13/44 Sydney Camm started a design, the P.1027, for a slightly enlarged Tempest powered by a Rolls-Royce R.46, which was projected to develop around 2,500–4,000 hp (1,864–2,983 kW). This engine would have driven eight-blade contra-rotating propellers. The radiator was to be moved into a ventral bath under the rear fuselage and wing centre section: the wingspan was 41 ft (12.5 m) and the length was 37 ft 3 in (11.4 m). The design was soon dropped in favour of the P.1030, which featured wing leading edge radiators and larger overall dimensions of 42 ft (12.8 m) wingspan and 39 ft 9 in (12.1 m) long. Top speed was expected to be in the region of 508 mph (817 km/h), with a rate of climb of 6,400 ft/min (1,951 m/min). Service ceiling was projected to be 42,000 ft (12,802 m).

Both tenders were dropped when Camm decided to follow the more promising jet-engined designs he was working on.

Tempest V in combat
The Tempest V was in the hands of operational squadrons by April 1944; 3 Squadron was the first to be fully equipped, closely followed by 486 (NZ) Squadron (the only Article XV unit to be equipped with the Tempest during the Second World War). A third unit—56 Squadron—initially kept its Typhoons and was then temporarily equipped with Spitfire IXs until sufficient supplies of Tempests were available. By the end of April 1944, these units were based at RAF Newchurch a new Advanced Landing Ground (ALG), where they formed 150 Wing, commanded by Wing Commander Roland Beamont. The new Wing was part of the Second Tactical Air Force (2nd TAF).

Most of the operations carried out by 150 Wing comprised high altitude fighter sweeps, offensive operations known as "Rangers" (long-range sorties inside enemy territory, specifically to attack ground vehicles) and anti-shipping reconnaissance. 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. 150 Wing was transferred back to the ADGB, where the Tempest squadrons racked up a considerable percentage of the total RAF kills over the flying bombs (638 of a total of 1,846 destroyed by aircraft).

In September 1944, Tempest units, based at forward airfields in England, supported Operation Market Garden, the Airborne attempt to seize a bridgehead over the Rhine. On 21 September 1944, as the V1 threat had receded, the Tempest squadrons were redeployed to the 2nd TAF, effectively trading places with the Mustang III squadrons of 122 Wing, which became part of the ADGB units deployed on bomber escort duties. 122 Wing now consisted of 3 Sqn., 56 Sqn., 80 Sqn., 274 Sqn. (to March 1945), and 486(NZ)Sqn. From 1 October 1944 122 Wing was based at B.80 Volkel Air Base near Uden, in the Netherlands. In February 1945 33 and 222 Sqns. of 135 Wing converted from Spitfire Mk IXs and, in March, were joined by 274 Sqn. 135 Wing was based at B.77 Gilze-Rijen airfield in the Netherlands.

The Tempest's primary role was to carry out "armed reconnaissance" operations deep behind enemy front lines. The Tempest was particularly well suited to the role because of its high speed at low to medium altitudes, its long range when equipped with two 45 gallon drop tanks, the good firepower of the four 20mm cannon and the good pilot visibility. Armed reconnaissance missions were usually flown by two sections (eight aircraft), flying in Finger-four formations, which would cross the front lines at altitudes of 7,000 to 8,000 feet: once the Tempests reached their allocated target area the lead section dropped to 4,000 feet or lower to search for targets to strafe, while the other section flew cover 1,000 feet higher and down sun. After the first section had carried out several attacks it would swap places with the second section and the attacks would continue until ammunition had been exhausted, after which the Tempests would return to base at 8,000 ft. Because the most profitable targets were usually some 250 miles from base the Tempests usually carried two 45 gallon drop tanks which were turned on soon after takeoff. Although there were fears that the empty tanks would explode if hit by flak, the threat never eventuated and, because they could be difficult to jettison, they were routinely carried throughout an operation with little effect on performance, reducing maximum speed by 5 to 10 mph and range by 2%.

In December 1944, 52 German fighters were downed and 89 trains destroyed, for the loss of 20 Tempests. Following the Luftwaffe's Operation Bodenplatte of 1 January 1945, 122 Wing bore the brunt of low to medium altitude fighter operations for the Second Tactical Air Force. Spitfire XIVs of 125 and 126 Wings often provided medium to high altitude cover for the Tempests. The Wing came under intense pressure, losing 47 pilots in January.

Tempests also scored a number of kills against the new German jets, including the Messerschmitt Me 262. Hubert Lange, a Me 262 pilot, said: "the Messerschmitt Me 262's most dangerous opponent was the British Hawker Tempest &mdash; extremely fast at low altitudes, highly-manoeuvrable and heavily-armed." Some Me 262s were destroyed with a tactic known to 135 Wing as the "Rat Scramble": Tempests on immediate alert took off when an Me 262 was reported to be airborne. They did not intercept the jet, but instead flew towards the Me 262 and Ar 234 base at Rheine-Hopsten. The aim was to attack jets on their landing approach, when they were at their most vulnerable, travelling slowly, with flaps down and incapable of rapid acceleration. The Germans responded by creating a "flak lane" of over 150 quadruple 20 mm (.79 in) guns at Rheine-Hopsten, to protect the approaches. After seven Tempests were lost to flak at Rheine-Hopsten in a single week, the "Rat Scramble" was discontinued. For a while, in March 1945, a strict "No, repeat, No ground attacks" policy was imposed; this only applied for a few days.

In air-to-air combat, the Tempest units achieved an estimated air combat success ratio of 7:1, accomplishing a 6:1 ratio against single seat enemy fighters. The top scoring Tempest pilot was Squadron Leader David C. "Foobs" Fairbanks DFC, an American who joined the Royal Canadian Air Force in 1941. By mid-1944, he was flying with 274 Squadron. When he was shot down and made a POW in February 1945, he had destroyed 11 or 12 German aircraft (and one shared) to make him the highest scoring Tempest ace.

Variants

 * Typhoon Mk II : The original designation of the Hawker Tempest.
 * Tempest Mk I : Prototype fitted with the Napier Sabre IV piston engine with oil coolers and radiators placed in the wing to reduce drag, one aircraft.
 * Tempest Mk III : Prototype fitted with the Rolls-Royce Griffon piston engine.
 * Tempest Mk IV : Tempest Mk III prototype re-engined with a Rolls-Royce Griffon 61 piston engine.
 * Tempest Mk V : Single-seat fighter, fighter-bomber aircraft, powered by the Napier Sabre II piston engine, 801 built at Langley.
 * Early series Tempest Mk V : The first 100 production aircraft were fitted with four long-barrel 20 mm (.79 in) Mark II Hispano cannons and continued to use some Typhoon components.
 * Mid to late series Tempest Mk V : The other 701 production aircraft were fitted with four short-barrel 20 mm Mark V Hispano cannons and other production line changes.
 * Tempest TT Mk 5 : After the Second World War a number of Tempest Mk Vs were converted into target tugs.
 * Tempest F Mk II : Single-seat fighter aircraft for the RAF, powered by a Bristol Centaurus radial piston engine, 402 built by Hawker at Langley and 50 by Bristol Aeroplane Company, Banwell.
 * Tempest FB Mk II : Single-seat fighter-bomber with underwing pylons for bombs and rockets.
 * Tempest F Mk VI : Single-seat fighter aircraft for the RAF engined with the Sabre V (2,340 hp), 142 built.

Operators

 * 🇨🇦 Canada (One Tempest V, acquired postwar for trials. )