Staff Writer (Updated: 5/1/2015):
British aircraft engineer Major Frank Bernard Halford had developed his H.1 engine (to become the "Goblin" turbojet) with enough thrust that a single installation of its type could power an airframe if given a short exhaust jetpipe for maximizing energy output and minimizing thrust loss. Halford combined resources with the de Havilland aviation firm and the DH.99 design was born. The DH.99 featured a twin-boom fuselage layout with a central nacelle containing the cockpit, proposed armament of four cannons, a powered retractable tricycle undercarriage and the jet powerplant. The skin was of all-metal and a short central fuselage nacelle was used to supply the shorter jet pipe length. After review, the Ministry of Aircraft Production requested the aircraft to feature construction of both wood and metal to which de Havilland obliged - having already garnered much hybrid construction practices with their war-winning prop-powered DH.98 Mosquito series. This revision created the new designation of "DH.100" in November of 1941. British authorities were intrigued enough to order a pair of prototypes under Specification E.6/41 and detailed design work was started on new aircraft then known as the "Spider Crab" in the middle of 1942. The prototype was assigned the in-house designation of LZ548/G.
First flight of a prototype occurred on September 20th, 1943 out of Hatfield with Geoffrey de Havilland, Jr at the controls. This aircraft was fitted with a Goblin 1 turbojet engine producing 2,700lbs of thrust. De Havilland, Jr. was the son of Geoffrey de Havilland, Sr., founder of the de Havilland firm. Delays meant that the fighter would not see production of the F.Mk I model until 1945, the initial production version flying for the first time in that year. Once the evaluations were complete and the DH.100 was accepted into service (know under the name of "Vampire") and production was outsourced to English Electric to allow de Havilland's facilities to work on other more pressing wartime needs. As such, most of the early Vampires were in fact English Electric products and some 244 of the initial Mk I fighters were ultimately delivered. The Vampire was also branched into the DH.113 dedicated nightfighter with radar, originally intended for Egypt, but redirected to the Royal Air Force due to an arms ban on the nation by the British government. The Vampire was spawned into the ever important trainer in the DH.115 Vampire T.11 and, amazingly, Vampire trainers were in RAF service up until 1966. At its peak usage, the Vampire stocked some 19 Royal Air Force squadrons around the world and a total of 3,268 examples of some 15 complete variants were ultimately produced for the British, Commonwealth forces and export customers.