Short Brothers SB5 (WG768)Short Brothers SB5 (WG768)

Short Brothers SB.5 (WG768)  [@ RAF Cosford]

A technical disagreement arose between the RAE [Royal Aircraft Establishment] and the design team at English Electric as to the best configuration for the supersonic Lightning. The original design incorporated highly swept wings and a low-set tailplane so the RAE decided to build a flying model to test wing-sweep and tailplane setting, especially at low speeds.

The contract was awarded to Short Brothers and Harland Ltd of Belfast on 2nd August 1950. The design was to allow for three different wing sweep angles (to be set on the ground) to 50, 60 and 69 and two different tail plane positions (low on the rear fuselage and on top of the fin). This necessitated two entirely different rear fuselages and tail units. WG768 flew on 2nd December 1952 and was an all-metal cantilever mid-wing monoplane with fixed undercarriage and powered by a Rolls Royce Derwent engine. During 1953 tests with 50 and 60 sweep were concluded with the high tail configuration. In January 1954 the low tail rear fuselage was fitted and tests continued for a further two years and proved that the English Electric configuration was correct i.e. 60 wing sweep and with a low-set tailplane.

Before fitting the final wing sweep configuration of 69 was tested, an ejector seat was fitted for the first time and the Derwent engine was changed for a Bristol Orpheus for greater thrust. The aircraft was returned to RAE Bedford in September 1960. The first flight was made in the new configuration on 18th October. After completion of its test programme the Empire Test Pilots School at Boscombe Down flew the machine to give students experience in flight-testing slender aircraft.

WG768 is preserved at RAF Cosford in the low-set tail configuration. Although essentially similar to the Lightning there are the many differences when compared with the P.1, notably the fin shape and single engine being the most obvious.