Bristol 188 - Operational History

Operational History

In May 1960, the first airframe was delivered to the Royal Aircraft Establishment at Farnborough for structural tests – loading tests both heated and unheated – before moving on to RAE Bedford. XF923 undertook the first taxiing trials on 26 April 1961, although due to problems encountered, the first flight was not until 14 April 1962. XF923 was intended to remain with Bristol for its initial flights and evaluation before turning it over to the MoA. XF926 had its first flight, using XF923s engines, on 26 April 1963. XF926 was given over to RAE Bedford for its flying programme. Over 51 flights, it managed a top speed of Mach 1.88 (1,440 mph : 2,300 km/h) at 36,000 ft (11,000 m). The longest subsonic Bristol 188 flight was only 48 minutes in length, requiring 70% of the fuel load to be expended to attain its operational altitude.

Measurements collected during testing were recorded onboard and transmitted to the ground station for recording. The flight information transmitted meant that a "ground pilot" could advise the pilot.

The project suffered a number of problems, the main being that the fuel consumption of the engines did not allow the aircraft to fly at high speeds long enough to evaluate the "thermal soaking" of the airframe, which was one of the main research areas it was built to investigate. Combined with fuel leaks, the inability to reach its design speed of Mach 2 and a takeoff speed at nearly 300 mph (480 km/h), the test phase was severely compromised. Nonetheless, although the 188 programme was eventually abandoned, the knowledge and technical information gained was put to some use for the future Concorde program. The inconclusive nature of the research into the use of stainless steel led to Concorde's being constructed from conventional aluminium alloys with a Mach limit of 2.2. Experience gained with the Gyron Junior engine, which was the first British gas turbine designed for sustained supersonic operation, additionally later assisted with the development of the Bristol (later Rolls Royce) Olympus 593 powerplant which was used on both Concorde and the BAC TSR-2.

Various proposals to further develop the 188 were considered including incorporating ramjets and rocket engines as well as considering fighter and reconnaissance variants. One serious proposal involved the fitting of "wedge" type intakes.

The announcement that all development was terminated was made in 1964, the last flight of XF926 taking place on 12 January 1964. In total the project cost £20 million. By the end of the programme, considered the most expensive to date for a research aircraft in Great Britain, each aircraft had to be "cannibalised" in order to keep the designated airframe ready for flight.