De Havilland Vampire - Design and Development

Design and Development

The Vampire was considered to be a largely experimental design due to its unorthodox arrangement and the use of a single engine, unlike the Gloster Meteor which was already specified for production. The low power output of early British jet engines meant that only twin-engine aircraft designs were considered practical; but as more powerful engines were developed, particularly Frank Halford's H.1 (later known as the Goblin), a single-engined jet fighter became more viable. De Havilland were approached to produce an airframe for the H.1, and their first design, the DH.99, was an all-metal, twin-boom, tricycle undercarriage aircraft armed with four cannon. The use of a twin boom kept the jet pipe short which avoided the power loss of a long pipe that would have been needed in a conventional fuselage. The DH.99 was modified to a mixed wood and metal construction in light of Ministry of Aircraft Production recommendations, and the design was renumbered to DH.100 by November 1941.

Under Air Ministry specification E.6/41 for two prototypes, design work on the DH.100 began at the de Havilland works at Hatfield in mid-1942, two years after the Meteor.

Originally named the "Spider Crab," the aircraft was entirely a de Havilland project, exploiting the company's extensive experience in building with moulded plywood for aircraft construction. Many of the basic design features were first used in their Mosquito fast bomber. It had conventional straight mid-wings and a single jet engine placed in an egg-shaped, aluminium-skinned fuselage, exhausting in a straight line.

Geoffrey de Havilland Jr, the de Havilland chief test pilot and son of the company's founder, test flew prototype Serial number LZ548/G on its maiden flight on 20 September 1943 from Hatfield. The flight took place only six months after the Meteor's maiden flight. The first Vampire flight had been delayed due to the need to send the only available engine fit for flight to America to replace one destroyed in ground engine runs in Lockheed's prototype XP-80. The production Vampire Mk I did not fly until April 1945, with most being built by English Electric Aircraft at their Preston, Lancashire factories due to the pressures on de Havilland's production facilities, which were busy with other types. Although eagerly taken into service by the RAF, it was still being developed at war's end, and never saw combat in the Second World War.

The Vampire was first powered by a Halford H1 (later renamed the "Goblin") producing 2,100 lbf (9.3 kN) of thrust, designed by Frank B Halford and built by de Havilland. The engine was a centrifugal-flow type, a design soon superseded post-war by the slimmer axial-flow units. Initially, the Goblin gave the aircraft a disappointingly limited range. This was a common problem with all the early jets, and later marks were distinguished by greatly increased fuel capacities. As designs improved the engine was often upgraded. Later Mk Is used the Goblin II; the F.3 onwards used the Goblin III. Certain marks were test-beds for the Rolls-Royce Nene, leading to the FB30 and 31 variants built in Australia. An unusual characteristic of the low positioning of the engine meant that a Vampire could not remain on idle for longer than a certain time because the heat from the jet exhaust would melt the tarmac on which it stood.

De Havilland initiated a private venture night fighter, the DH.113 intended for export, fitting a two seat cockpit closely based on that of the Mosquito night fighter, and a lengthened nose accommodating AI Mk X radar. An order to supply the Egyptian Air Force was received, but this was blocked by the British government as part of a general ban on supplying arms to Egypt. Instead the RAF took over the order and put them into service as an interim between the retirement of the de Havilland Mosquito night fighter and the full introduction of the Meteor night fighter. Removal of the radar from the night fighter and fitting of dual controls gave a jet trainer, the DH.115 Vampire which entered British service as the Vampire T.11. This was built in large numbers, both for the RAF and for export.

A total of 3,268 Vampires were built in 15 versions, including a twin-seat night fighter, trainer and a carrier-based aircraft designated Sea Vampire.

The Vampire was used by some 31 air forces. Germany, the Netherlands, Spain and the U.S. were the only major Western powers not to use the aircraft type.

In 1947 Wing Commander Maurice Smith, then-Editor of Flight magazine, stated upon piloting his first jet-powered aircraft, a Vampire Mk III; "Piloting a jet aircraft has confirmed one opinion I had formed after flying as a passenger in the Lancastrian jet test beds, that few, if any, having flown in a jet-propelled transport, will wish to revert to the noise, vibration and attendant fatigue of an airscrew-propelled piston-engined aircraft"