The Hawker Tempest was a British fighter aircraft primarily used by the Royal Air Force in the Second World War.
During development of the earlier Hawker Typhoon, the design team, under the leadership of Sydney Camm, had already planned out a series of design improvements; these improvements cumulated in the Hawker P. 1012, otherwise known as the Typhoon II or Thin-Wing Typhoon.
Although the Typhoon was generally considered to be a good design, Camm and his design team were disappointed with the performance of its wing, which had proved to be too thick in its cross section, and thus created airflow problems which inhibited flight performance, especially at higher altitudes and speeds where it was affected by compressibility.
The Typhoon’s wing, which used a NACA 4-digit series wing section, had a maximum thickness-to-chord ratio of 19.5 per cent (root) to 12 per cent (tip), in comparison to the Supermarine Spitfire’s 13.2 per cent tapering to 6 per cent at the tip, the thinner design being deliberately chosen to reduce drag.
In addition, there had been other issues experienced with the Typhoon, such as engine unreliability, insufficient structural integrity, and the inability to perform high altitude interception duties.
In March 1940, engineers were assigned to investigate the new low–drag laminar flow wing developed by NACA in the United States, which was later used in the North American P-51 Mustang.
A laminar flow wing adopted for the Tempest series had a maximum thickness-to-chord ratio of 14.5 per cent at the root, tapering to 10 per cent at the tip.
The maximum thickness of the Tempest wing was set further back at 37.5 per cent of the chord versus 30 per cent for the Typhoon’s wing, reducing the thickness of the wing root by five inches on the new design.
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 a near-elliptical shape to accommodate the 800 rounds of ammunition for the four 20 mm Hispano cannons, which were moved back further into the wing.
The new 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 Igal (345 L) fuel tank.
In addition, two inter-spar wing tanks, each of 28 Igal (127 L), were fitted on either side of the centre section and, starting with late model Tempest Vs, a 30 Igal (136 L) tank was carried in the leading edge of the port wing root, giving the Tempest a total internal fuel capacity of 162 Igal (736 L).
Another important feature of the new wing was Camm’s proposal that the radiators for cooling the engine be fitted into the leading edge of the wing inboard of the undercarriage.
This eliminated the distinctive “chin” radiator of 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.
The new wing and airfoil, and the use of a four-bladed propeller, acted to eliminate the high frequency vibrations that had plagued the Typhoon.
The design team also chose to adopt the new Napier Sabre IV engine for the Tempest, drawings of which had become available to Hawker in early 1941.
In February 1941, Camm commenced a series of discussions with officials within the Ministry of Aircraft Production on the topic of the P.1012.
In March 1941 of that year, clearance to proceed with development of the design, referred to at this point as the Typhoon II, was granted.
At this point, work was undertaken by a team of 45 draughtsmen at Hawker’s wartime experimental design office at Claremont, Esher to convert the proposal into technical schematics from which to commence manufacture.
In March 1941, the Air Ministry issued specification F.10/41 that had been written to fit the aircraft.
By October 1941, development of the proposal had advanced to the point where the new design was finalised.
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 F II
Single-seat fighter aircraft for the RAF, powered by a Bristol Centaurus radial piston engine.
Tempest FB II
Single-seat fighter-bomber with underwing pylons for bombs and rockets.
Tempest Mk III
Prototype fitted with the Rolls-Royce Griffon piston engine.
Tempest Mk IV
Tempest Mk III prototype re-engine 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.
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 to serve as target tugs.
Tempest F Mk VI
Single-seat fighter aircraft for the RAF with the Sabre V (2,340 hp)engine.
Specifications
Crew
1
Length
33 ft 8 in (10.26 m)
Wingspan
41 ft 0 in (12.50 m)
Height
14 ft 10 in (4.52 m) (tail in rigging position with one propeller blade vertical);
16 ft 1 in (4.90 m) (tail down with one propeller blade vertical)
Wing area
302 sq ft (28.1 m2)
Airfoil
Root
Hawker H.14/14/37.5
Tip
Hawker H.14/10/37.5
(Maximum thickness at 37.5% chord)
Gross weight
11,400 lb (5,171 kg) as interceptor;
12,500 lb (5,700 kg) with 2x 500 lb (230 kg) bombs;
13,500 lb (6,100 kg) with 2x 1,000 lb (450 kg) bombs)
Fuel capacity
160 imp gals (190 US gal; 730 l) internal with optional 90 imp gal (110 US gal; 410 l) or 180 imp gals (220 US gal; 820 l) in two drop tanks under wings
