Tag Archives: LZ548/G

20 September 1943

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Geoffrey de Havilland, Jr., exits the cockpit of one of the company's jet aircraft. (Photograph Courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Geoffrey de Havilland, Jr., exits the cockpit of one of the company’s jet aircraft. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

20 September 1943: Geoffrey Raoul de Havilland, Jr., chief test pilot of the de Havilland Aircraft Co., Ltd., made the first flight in the prototype DH.100, LZ548/G, at Hatfield, Hertfordshire. (The “/G” in the identification indicated that the aircraft was to be guarded at all times.) Assigned the code name Spider Crab,  the production DH.100 would be better known as the de Havilland Vampire.

The flight lasted approximately 30 minutes and the airplane exceeded 400 miles per hour (644 kilometers per hour). De Havilland reported that the prototype was trimmed with the left wing down, had overly sensitive ailerons and demonstrated instability in yaw with rudder applications.

This oscillation in the yaw axis—called “snaking”—was determined to be a result of the overly effective vertical fins. After wind tunnel and flight testing, it was decided to reduce the fins’ area, resulting in the flat top configuration seen in bottom photograph.

Right front view of the first prototype de Havilland DH.100, LZ548/G.
Right front view of the first prototype de Havilland DH.100, LZ548/G, prior to its first flight. The letter “P” in a circle next to the RAF insignia identifies the airplane as a prototype. The “/G” in the identification number indicates that a guard is required at all times. (De Havilland Aircraft Co., Ltd.)

The DH.100 was a single-seat, single-engine fighter powered by a turbojet engine. The twin tail boom configuration of the airplane was intended to allow a short exhaust tract for the engine, reducing power loss in the early jet engines available at the time.

Right side view of the de Havilland DH.100 Spider Crab LZ548/G.
Right side view of the de Havilland DH.100 Spider Crab LZ548/G.

LZ548/G was originally powered by a Halford H.1 turbojet which produced 2,300 pounds of thrust (10.231 kilonewtons) at 9,300 r.p.m. This engine was produced by de Havilland and named Goblin.

av_gb_4603_jet-history_goblin_p080_wThe Goblin is a linear descendant of the early Whittle units. It comprises a single-sided centrifugal compressor delivering air to sixteen combustion chambers grouped symmetrically around the axis of the unit and leading to the nozzle of the single-stage axial turbine which drives the compressor. Compressor impeller and turbine rotor are coupled by a tubular shaft to form a single rotating assembly which is mounted on only two ball bearings. The maximum diameters of the engine, around the compressor casing, is 50in., [1.27 meters] and with a jet pipe of minimum length fitted the overall length is about 8ft. [2.438 meters] Equipped with a jet pipe and all the necessary engine auxiliaries the dry weight of the complete unit is 1,500 lb. [680 kilograms] Fuel consumption is at the rate of 1.23 lb. / hr. per lb. thrust.

—FLIGHT and AIRCRAFT ENGINEER, No. 1923. Vol. XLVIII. Thursday, 1 November 1945 at Page 472, Column 2

The Vampire entered service with the Royal Air Force in 1945 and remained a front-line fighter until 1953. 3,268 DH.100s were built.

Right rear quarter view of the prototype de Havilland DH.100, LZ548/G.
Right rear quarter view of the prototype de Havilland DH.100, LZ548/G. In this photograph, the airplane’s vertical fins have been squared off. This would be a feature of the production Vampire F.1.

The first of the three prototype Vampires, LZ548, crashed after takeoff from Hatfield, 23 July 1945, due to a fuel pump failure. Geoffrey Pike, the pilot, was not injured.

© 2016, Bryan R. Swopes