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Aviation History
1962
1962 - 0695.PDF
BRISTOL 188 A Versatile Research Aeroplane BY THE TECHNICAL EDITOR AFTER a long period of incubation, the Bristol 188 flew.for the first time on April 14. It is now possible for Flight International to describe the 188 programme, and outline what it is intended to accomplish. The Bristol 188 is a stainless-steel research aircraft built under contract to the Ministry of Aviation. No other British aeroplane has posed such severe manufacturing problems; and the fact that these have been solved means that the project has already accom plished its first objective. The aircraft is not particularly large, and in appearance is surprisingly conventional; yet every portion of its structure, every bolt, every fluid seal and cable connector, and even the manner in which flight data will be measured and recorded, have all been the subject of years of painstaking development. The 188 is a focal point for a major advance in the technology of high speed aeroplanes, and, although the world of missiles and space craft into which it has now emerged is a very different one from that of 1954 when the project was initiated, it has not completely been overtaken by events. In fact, it should prove to be a valuable research tool. Previous articles, notably those published on April 26, 1957, and April 25,1958, have discussed the background to Experimental Requirement 103 and the F.23/49 specification, which eventually led to the Fairey FD.2 and English Electric Lightning. These requirements called for aircraft able to fly for several minutes at Mach numbers of the order of 1.4; and the fact that the FD.2 set a world speed record at over Ml.73 while the Lightning is in opera tional service at M2 suggests that the original research requirement was not over-ambitious. Should its demands ever come to be published, Experimental Requirement 134 may likewise appear conservative. As much can already be deduced, for it clearly called for an aeroplane capable of flight at Mach numbers of the order of 2, and with sufficient fuel to be able to maintain this speed long enough for more-or-less steady, as well as transient, conditions to be investigated. Originally several manufacturers prepared designs to meet ER.134, but when the Ministry of Supply (now Ministry of Avia tion) finalized the specification in 1954 Bristol Aircraft Ltd (now part of British Aircraft Corporation) were chosen as the manufac turer. A contract was placed covering the design and development of the Bristol Type 188, and the programme now comprises two flight aircraft plus one structural-test specimen, three aircraft for weapons research having been cancelled. Configuration Throughout the programme the Bristol 188 has been regarded solely as a research vehicle. It was obviously desirable to be able to "soak" at full speed under conditions of severe kinetic heating; maximum endurance was also required in order to increase the data gathered per sortie and provide adequate reserves. The Ministry demanded the ability to take off and land conventionally. Basic configuration of the aircraft was thus deter mined by the need to accommodate the pilot, a large quantity of fuel, undercarriage, instrumentation, and powerplants so arranged that new intakes, nozzles and engines could be installed with minimum difficulty. These requirements led naturally to the layout reached in 1955. As discussed in the next section of this article, nearly the whole airframe is made of stainless steel. Bristol found that this tied in particularly well with their choice of an essentially unswept wing, which facilitated mounting the engines well outboard in self-con tained nacelles. One of the disadvantages of a straight wing is the large c.p. movement across the transonic regime, and this c.p. travel was greatly reduced by sweeping back the leading edge out board of the nacelles. The final wing shape evolved as a result of extensive flutter and tunnel investigations, particularly into trim and stability. This testing also confirmed the use of a tailplane mounted at the top of the vertical tail; and comparison of the two three-view drawings (pages 694 and 696) reveals the growth in area of the latter. Exceptionally slender, the fuselage has a minimum cross-section
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