The Bristol 188 was a British supersonic research aircraft built by the Bristol Aeroplane Company in the 1950s. Its length, slender cross-section and intended purpose led to its being nicknamed the "Flaming Pencil".

Design and development

The aircraft had its genesis in Operational Requirement 330 for a high-speed reconnaissance aircraft, which eventually developed into the Avro 730. As the 730 was expected to operate at high speeds for extended periods of time, more data was needed on high-speed operations, leading to Oerational Requirement ER.134T for a testbed capable of speeds greater than Mach 2. The aircraft was expected to run at these speeds for extended periods of time, allowing it to study kinetic heating effects on such an aircraft.

Several firms took interest in this very advanced specification and the eventual contract (6/Acft/10144) was awarded to Bristol Aircraft in February 1953.

Bristol gave the project the type number 188, of which three aircraft were to be built, one a pure test bed and the other two (constructor numbers 13518 and 13519) for flight testing. Under contract number KC/2M/04/CB.42(b) serial numbers XF923 and XF926 were given on 4 January 1954 to the two that would fly. To support the development of the Avro 730 Mach 2 reconnaissance bomber, another three aircraft were ordered (Serial Numbers XK429, XK434 and XK436). The order was cancelled when the Avro 730 programme was cancelled in 1957 as part of the review of defence spending.

The advanced nature of the aircraft meant that 12% chromium stainless steel with a honeycomb centre was used for the construction of the outer skin, to which no paint was applied, but problems with the new Argon arc welding technique known as puddle welding caused long delays and was less than satisfactory. The W. G. Armstrong Whitworth company gave much technical help and support to Bristol during this period.

A quartz-lined windscreen and canopy and cockpit refrigeration system were designed and fitted but were never tested in the environment for which they had been designed.

Rolls-Royce engines were at first selected to power the 188, but five engine combinations were evaluated: two with Rolls Royce Avon 200s, two with the de Havilland Gyron Junior and one with an AJ.65, the last disintegrating on test. But the final choice for the 188 were two 10,000 lbf (44 kN) thrust Gyron Junior DGJ10Rs developing 14,000 lbf (62 kN) of thrust on reheat at sea level and 20,000 lbf (89 kN) at Mach 2 at 36,000 ft (11,000 m). Unfortunately this choice of powerplant resulted in the 188 having an endurance of only 25 minutes, which was too little time for any serious high speed research. Test pilot Godfrey Auty reported that while the 188 transitioned smoothly from subsonic to supersonic flight, the Gyron Junior engines were prone to surging beyond that speed, causing the aircraft to pitch and yaw.

Testing and evaluation

Farnborough in May 1960 saw the first aircraft delivered for structural tests before moving on to RAE Bedford. XF923 undertook the first taxiing trials on 26 April 1961 but the first flight was not until 14 April 1962 due to problems encountered. XF926 had its first flight on 26 April 1963 managing to reach a speed of Mach 1.88 (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.

The project suffered a number of problems; the main being - as mentioned above - that the fuel consumption of the engines didn't 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. Also, the takeoff speed was nearly . Though it 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, 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.

In total the project cost £20 million . Various proposals to develop the 188 were considered including: ramjets, rockets, a fighter and reconnaissance variants. One serious proposal involved the fitting of "wedge" type intakes, but all development was terminated in 1964, the last flight of XF926 taking place on 12 January 1964.

Survivors

In April 1966, both 188 fuselages were transported to the Proof and Experimental Establishment at Shoeburyness, Essex to act as targets for gunnery trials, but during 1972 XF926 was dismantled and moved to RAF Cosford (minus engines) to act as instructional airframe 8368M, and is preserved at the RAF Museum, Cosford near Wolverhampton. XF923 was subsequently scrapped at Foulness.

Operators

• Royal Air Force

Specifications (Bristol 188)

See also

References

Notes

1. "Bristol Aircraft." Gloucestershire Transport History. Retrieved: 5 January 2008.
2. Winchester 2005, p. 198.

Bibliography

• Winchester, Jim. The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters. London: Amber Books Ltd., 2005. ISBN 1-904687-34-2.

External links

• Bristol Type 188 (ER.134)8
• Royal Air Force Museum Bristol Type 188