Built mainly of stainless steel, this aircraft was designed to investigate the effects of heat on aircraft structures at very high speeds. To protect the pilot against heat build-up a special cockpit refrigeration system was installed. Nicknamed ‘Flaming Pencil’, only two Bristol 188s ever flew, a third being used for ground tests.
Data collected during test-flying could be transmitted directly to a ground station for immediate evaluation. The data provided was essential for the development of the proposed Avro 730 high-speed, high-altitude reconnaissance aircraft. The prototype 188, XF923, made its maiden flight on 14 April 1962 and its public debut at Farnborough in September of that year.
Both Bristol 188s were powered by de Havilland Gyron Junior engines; the first British engine designed for sustained running at supersonic speeds. Experience gained with this engine was later applied to the Olympus engines which power Concorde.
Although a maximum speed of Mach 1.88 was reached this fell short of the required Mach 2 performance. This, combined with fuel leaks, an endurance of only 25 minutes and the cancellation of the Avro 730, led to the cancellation of the Bristol 188 project in 1964.