This article is about the Second World War piston-powered fighter aircraft. For the later jet-powered fighter aircraft, see Eurofighter Typhoon
The Hawker Typhoon (Tiffy in RAF slang) is a British single-seat fighter-bomber, produced by Hawker Aircraft. It was intended to be a medium–high altitude interceptor, as a replacement for the Hawker Hurricane, but several design problems were encountered and it never completely satisfied this requirement.
The Typhoon was originally designed to mount twelve .303 inch (7.7 mm) Browning machine guns and be powered by the latest 2000 hp engines. Its service introduction in mid-1941 was plagued with problems and for several months the aircraft faced a doubtful future. When the Luftwaffe brought the formidable Focke-Wulf Fw 190 into service in 1941, the Typhoon was the only RAF fighter capable of catching it at low altitudes; as a result it secured a new role as a low-altitude interceptor.
The Typhoon became established in roles such as night-time intruder and long-range fighter. From late 1942 the Typhoon was equipped with bombs and from late 1943 RP-3 ground attack rockets were added to its armoury. With those weapons and its four 20mm Hispano cannon, the Typhoon became one of the Second World War's most successful ground-attack aircraft.
Design and development
The unarmed first prototype Typhoon P5212 taken just before its first flight. The prototype had a small tail unit and a solid fairing behind the cockpit, which was fitted with "car door" style access hatches; no inner wheel doors were fitted and the Sabre engine used three exhaust stubs either side of the cowling.
Even before Hurricane production began in March 1937, Sydney Camm had embarked on designing its successor. Two preliminary designs were similar and were larger than the Hurricane. These later became known as the "N" and "R" (from the initial of the engine manufacturers), because they were designed for the newly developed Napier Sabre and Rolls-Royce Vulture engines respectively. Both engines used 24 cylinders and were designed for over 2,000 hp (1,500 kW); the difference between the two was primarily in the arrangement of the cylinders – an H-block in the Sabre and an X-block in the Vulture. Hawker submitted these preliminary designs in July 1937 but were advised to wait until a formal specification for a new fighter was issued.
In March 1938, Hawker received from the Air Ministry, Specification F.18/37 for a fighter which would be able to achieve at least 400 mph (640 km/h) at 15,000 feet (4,600 m) and specified a British engine with a two-speed supercharger. The armament fitted was to be twelve .303 inch Browning machine guns with 500 rounds per gun, with a provision for alternative combinations of weaponry. Camm and his design team started formal development of the designs and construction of prototypes.[nb 1]
The basic design of the Typhoon was a combination of traditional Hawker construction (such as used in the earlier Hawker Hurricane) and more modern construction techniques; the front fuselage structure, from the engine mountings to the rear of the cockpit, was made up of bolted and welded duralumin or steel tubes covered with skin panels, while the rear fuselage was a flush-riveted, semi-monocoque structure.[nb 2] The forward fuselage and cockpit skinning was made up of large, removable duralumin panels, allowing easy external access to the engine and engine accessories and most of the important hydraulic and electrical equipment.
The wing had a span of 41-foot-7-inch (12.67 m), with a wing area of 279 sq ft (29.6 sq m). It was designed with a small amount of inverted gull wing bend; the inner sections had a 1° anhedral, while the outer sections, attached just outboard of the undercarriage legs, had a dihedral of 5½°. The airfoil was a NACA 22 wing section, with a thickness to chord ratio of 19.5% at the root tapering to 12% at the tip.
The wing possessed great structural strength, provided plenty of room for fuel tanks and a heavy armament, while allowing the aircraft to be a steady gun platform. Each of the inner wings incorporated two fuel tanks; the "main" tanks, housed in a bay outboard and to the rear of the main undercarriage bays, had a capacity of 40 gallons; while the "nose" tanks, built into the wing leading edges, forward of the main spar, had a capacity of 37 gallons each. Also incorporated into the inner wings were inward-retracting landing gear with a wide track of 13 ft 6¾ in.
By contemporary standards, the new design's wing was very "thick", similar to the Hurricane before it. Although the Typhoon was expected to achieve over 400 mph (640 km/h) in level flight at 20,000 ft, the thick wings created a large drag rise and prevented higher speeds than the 410 mph at 20,000 feet (6,100 m) achieved in tests.[nb 3] The climb rate and performance above that level was also considered disappointing. When the Typhoon was dived at speeds of over 500 mph (800 km/h), the drag rise caused buffeting and trim changes. These compressibility problems led to Camm designing the Typhoon II, later known as the Tempest, which used much thinner wings with a laminar flow airfoil.
The second prototype P5216 in the standard RAF camouflage of 1941, possibly with yellow undersurfaces. The retractable tailwheel and main wheels now had doors fitted. Six exhaust stubs and the later standardised four cannon armament were other changes from P5212.
The first flight of the first Typhoon prototype, P5212, made by Hawker's Chief test Pilot Philip Lucas from Langley, was delayed until 24 February 1940 because of the problems with the development of the Sabre engine. Although unarmed for its first flights, P5212 later carried 12 .303 in (7.7 mm) Brownings, set in groups of six in each outer wing panel; this was the armament fitted to the first 110 Typhoons, known as the Typhoon IA.[nb 4] P5212 also had a small tail-fin, triple exhaust stubs and no wheel doors fitted to the centre-section. On 9 May 1940 the prototype had a mid-air structural failure, at the join between the forward fuselage and rear fuselage, just behind the pilot's seat. Philip Lucas could see daylight through the split but instead of bailing out, landed the Typhoon and was later awarded the George Medal.
On 15 May, the Minister of Aircraft Production, Lord Beaverbrook, ordered that resources should be concentrated on the production of five main aircraft types (the Spitfire and Hurricane fighters and the Whitley, Wellington and Blenheim bombers). As a result, development of the Typhoon was slowed, production plans were postponed and test flying continued at a reduced rate.
As a result of the delays the second prototype, P5216, first flew on 3 May 1941: P5216 carried an armament of four belt-fed 20 mm (0.79 in) Hispano Mk II cannon, with 140 rounds per gun and was the prototype of the Typhoon IB series. In the interim between construction of the first and second prototypes, the Air Ministry had given Hawker an instruction to proceed with the construction of 1,000 of the new fighters. It was felt that the Vulture engine was more promising, so the order covered 500 Tornadoes and 250 Typhoons, with the balance to be decided once the two had been compared. It was also decided that because Hawker was concentrating on Hurricane production, the Tornado would be built by Avro and Gloster would build the Typhoons at Hucclecote. Avro and Gloster were aircraft companies within the Hawker Siddeley group. As a result of good progress by Gloster, the first production Typhoon R7576 was first flown on 27 May 1941 by Michael Daunt, just over three weeks after the second prototype.