Hawker Sea Hawk - Design and Development

Design and Development

In the final years of the Second World War, Hawker's design team explored jet engine technology, initially looking at "stretching" and modifying the existing Hawker Fury/Sea Fury planform fitting a mid-engine Rolls-Royce Nene jet engine and moving the cockpit to the extreme front of the fuselage, creating the P.1035. With encouragement from the Air Ministry, the design was altered substantially, with the wing losing the elliptical shape of the Fury and featuring wing-root air intakes and short bifurcated jet exhausts (which gained the name "trouser legs"). This redesign culminated in building the private venture P.1040. The unusual bifurcated jet pipe reduced jet pipe power loss and freed up space in the rear fuselage for fuel tanks, allowing the aircraft to have a longer range than many other early jets. The aircraft's fuselage fuel tanks were fore and aft of the engine giving a stable centre of gravity in flight. Initially, the P.1040 was intended for the Royal Air Force (RAF) as an interceptor, even though a top speed of only 600 mph was forecast. When in 1945 the RAF showed little interest in the project because it offered insufficient advance over jet fighters already in service such as the Gloster Meteor and de Havilland Vampire, the P.1040 was offered to the Admiralty as a fleet support fighter, the P.1046.

The P.1040 prototype (VP401), sometimes called the Hawker N.7/46 after the naval specification flew on 2 September 1947, piloted by Bill Humble. Teething problems including airframe vibrations and tail buffeting led to a redesign of the rear jetpipe fairings and the addition of a bullet fairing on the tail. Other minor issues including high stick forces and windshield distortion were addressed while a long takeoff run was attributed to the low powered Nene 1 that had been not rated for its full power settings.

A fully navalised prototype, VP413 equipped with folding wings, catapult spools and full armament did not fly until 31 August 1948. A third prototype which flew in 1949 incorporated a number of modifications from the second prototype, including the fitting of a longer arrester hook when a number of "bolters" were experienced in the dummy deck trials. After the longer hook was incorporated, the modification was carried though the remaining production runs. The first carrier trials occurred aboard the fleet aircraft carrier HMS Illustrious that same year. VP401, the first prototype continued in the flight test programme and before being retired, was involved in two significant events. On 1 August 1949, the Royal Navy entered VP401 in the National Air Races, winning the SBAC Challenge Cup Race, beating a Vampire 3 and DH 108. The prototype was later converted into the Hawker P.1072 with the addition of an auxiliary rocket engine, becoming the first British rocket-powered aircraft. After a few flights were made in 1950, the rocket engine blew up during a test and although repaired, the airframe was scrapped.

The third prototype joined a specially-prepared Vampire Mk 21 in testing the feasibility of operating without an undercarriage utilizing a flexible deck. Flying from Farnborough, VP413 successfully completed both catapult launches and "rubber sheet" deck landings, with the undercarriage remaining retracted throughout the flights. Although the system was proved, the project was abandoned in 1950 when more powerful engines precluded the need to radically adapt the design to the concept of combat aircraft without undercarriages.

Over 100 of the aircraft, named Sea Hawk, were subsequently ordered by the Royal Navy. The first production Sea Hawk F1 was WF143, which flew on 14 November 1951 with 39 ft (12 m) wingspan and a tailplane of increased area.

Unlike its rival, the Supermarine Attacker (the first jet to enter service with the FAA), the Sea Hawk had a tricycle undercarriage rather than a tail-wheel, making it easier to land on carriers. It was a fairly conventional design however, while other contemporary aircraft, e.g. the F-86 Sabre, had adopted swept wings, the Sea Hawk had straight wings. Swept wing versions (P.1052 and P.1081) were built and experience gained with the latter was instrumental in developing the Hawker Hunter design. The Sea Hawk was still a reliable and elegant aeroplane though its cautious design meant it would only have a brief career before being superseded by more advanced aircraft.