Hawker Typhoon

G. Hawker Engineering Co Ltd, formed in 1920 as a successor to the old firm of Sopwith, had soon become world-famous for its excellent fighters. The first of these was the Woodcock, which began production in May 1925. It was not surprising therefore that, after supplying the Service with this and a succession of other outstanding fighter aeroplanes, this aircraft constructor was successful in obtaining the contract for the Hawker Typhoon.

The Typhoon, however, came close to being aborted before its last-minute birth as a distinguished destroyer of the enemy in the air and on the ground. Its survival to play a prominent part in the RAFs battle order was, as the Duke of Wellington said about the Battle of Waterloo, ‘the nearest run thing you ever saw in your life’. This aircraft was intended to succeed the Hawker Hurricane as an interceptor fighter, which had itself been innovative: not only because it was the RAFs first monoplane fighter and its first to exceed 300mph, but also because it was Britain’s first to have a monococque fuselage and, later, stressed steel wings as well. Hawker’s duralumin tube and steel type of construction, which was one of the features that the two fighters were to have in common, was also unique to the manufacturer: so a lot was expected of the Typhoon. The Hurricane was sweet to handle, but its bulky successor turned out to be a maverick; hence the reluctance, at one stage, to proceed with its development.

The Typhoon’s history began in 1937 with Air Ministry Specification F.18/37, which put emphasis on the required cannon armament. Sidney Camm, Hawker’s Chief Designer, had already discussed the requirement for two new fighters with the Air Ministry. On 15 January 1938 Appendix B was added to the specification, setting out the Operational Requirement in detail, and sent to all ten companies on the Air Ministry’s Approved List of aircraft manufacturers. The specification called for the production of two new interceptor fighters designed to be powered by the 2000hp 24-cylinder engines that were being developed. Among the qualities demanded were a speed of at least 400mph at 20,000ft, a minimum of fifty per cent greater weight of fire than the Hurricane or Supermarine Spitfire and suitability to operate from grass airfields. Six 20mm cannon were envisaged, but until reliable guns of that calibre became available twelve Browning machine-guns would take their place.

Whatever engine was chosen, it would be at least sixty per cent heavier than the Hurricanes (and later, Spitfires) Merlin. Sidney Camm had to come to terms with the fact that both these new aircraft would therefore compare with his sleek Fury and Demon fighters, and equally graceful Hart light bomber, like a cruiser-weight boxer with a ballet dancer. (In the 1930 annual Air Defence Exercise, the Hart was actually faster than the Siskin fighters that tried to intercept it.) The Hawker R Type new fighter, later named Tornado, was to have the 24-cylinder -configuration Rolls-Royce Vulture engine, which comprised four Rolls-Royce Peregrine engine blocks with a single crankshaft. It was also mounted in the Avro Manchester twin-engine bomber, whose subsequent ill repute was owed to this engines inability to deliver its designed power and to its abundant failures.

The N-type new fighter, destined to be named Typhoon, which was also being built by Hawker, would have the Napier Sabre 24 cylinder H-configuration sleeve-valve engine with two shafts. Each of this engine’s upper and lower light alloy blocks had twelve opposed cylinders with two inlet and three exhaust ports and four-port sleeves. The power unit also comprised a two-speed supercharger, four-stroke updraught carburettor and Koffman starter. In case the Sabre failed to meet requirements, the Typhoon was designed also to be able to mount the Vulture. The anhedral inner wing and dihedral outer wing panels gave both the Typhoon and the Tornado a slightly gull-winged look. There were fuel tanks in the leading edges and guns were housed outboard of the inward-retracting landing gear. The Air Ministry placed an order for four prototypes, two with the Sabre engine and two with the Vulture. By the end of 1939, three months after the declaration of war, Hawker had been given an Instruction To Proceed (ITP) which ordered 1000 Typhoons. Initially, the Vulture engine behaved better than it had in the Manchester and the first Tornado prototype (P5219) was the first of the two new fighters to fly – on 6 October 1939. This had been built in the Hawker experimental shop at Kingston-on-Thames and was taken by road to the grass airfield at Langley, near Staines in Middlesex, where a final assembly plant was being set up. Philip Lucas, a flight lieutenant in the R.A.F. Reserve, who was soon to be appointed Chief Test Pilot, took it up for its maiden flight, which presented new problems: a high drag rise at speeds near 400mph, and compressibility. The latter was a phenomenon that would become familiar with the first generation of supersonic aircraft. The lessons learned from the Tornado were directly relevant to designing the Typhoon.

By March the next year the Vulture engine was developing 2010 horsepower. The production schedule laid down in July 1939 had catered for delivery of the first aeroplane by July 1940 and of the 500th by September 1941. The complex Sabre engine was causing delays to the Typhoon and the respective dates had to be put back to October 1940 and January 1942. The first prototype (P5212) did not make its maiden flight until 24 February 1940. In consequence, the Tornado was regarded as the more promising aircraft. Production of both new fighters was further retarded during the Battle of Britain – officially deemed to have begun on 10 July 1940 – when priority was given to the manufacture of Hurricanes. The Minister of Aircraft Production ordered manufacture to be concentrated also on Spitfires, and three bomber types: Blenheim, Wellington and Whitley. All this meant a nine-month setback in the constructing and prototype testing rate of Tornados and Typhoons. The first production plan, pre-dating the decision to discontinue the Vulture engine, had envisaged the building of 500 Tornados and 250 Typhoons; the type of the remaining 250 was to be decided when the two engines came into series production. This, of course, was now thwarted. Hawker, already fully stretched by the demand for more Hurricanes, therefore sub-contracted Tornado production to A.. Roes Manchester factory and Typhoon production to the Gloster Aircraft Co at Hucclecote, near Gloucester. Both of these companies were members of the Hawker Siddeley Group. The second Tornado prototype (P5224) was not flown until 5 December 1940 and the first production one (R7936) made its maiden flight on 29 August 1941. Only two more prototype Tornados were built before this aeroplane was cancelled because Rolls-Royce ceased making the Vulture engine. The Typhoon profited further from lessons learned while testing the stillborn Tornado. The least of its grave imperfections was that the oil cooling was inefficient, so the air inlet for this purpose had to be redesigned and repositioned before manufacture, based on the final prototype, began. The next change was to move the radiator scoop from its original position in line with the wings, as in the Hurricane, to beneath the wings in the beard' position. Not only was the Sabre engine very heavy, but also the radiator and oil cooler had to be placed in the nose. In order for the aeroplanes centre of gravity to be correctly positioned, the whole assembly had to be shifted seven inches astern. In consequence, the bearers, structural parts and upper nose panels had involved changes.

Read more about Hawker Typhoon in Hawker Typhoon: The Combat History, by Richard Townshend Bickers