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Aviation History
1964
1964 - 2113.PDF
134 FLIGHT International, 23 July 196 BAC.221 General-arrangement drawing by the former Fairey Aviation Co showing the first, minimum proposed ogee modification to the ER.I03 (FD.2) research aircraft. The dotted lines indicate the outline of the original delta wing Data for original ogee pro- posal: Span, 24ft 8.-tin Overall length, parallel to fuselage datum, 54ft 7.5in Height, from static ground line, 10ft 5in Gross wing area, 540 sq ft control-jack modifications to be made by Fairey Engineering. The second of these proposals was considered too much of a compromise; it was not truly "slender," and had insufficient fuel capacity. Accordingly it was agreed in September 1960 to effect the full modification, the rebuilt aircraft receiving the Bristol type- number of 221. On September 5 the first FD.2 (the record-breaker) was flown to Filton, and design work proceeded apace. Manufac- ture of hardware started in April 1961, and construction of the 221 was completed on July 7, 1963, As is frequently the case with British programmes, and especially those involving research aircraft, the 221 has been produced on a shoestring. British Aircraft Corporation have at every turn had to adopt cost-cutting methods in order to keep within the fixed price stipulated in the contract. This frugality dominated the whole programme. A job of this nature can easily "run away with itself" and incur a large bill for the taxpayer, but the Bristol management maintained careful control by means of the PERT critical-path procedure. This had the further advantage of acting as a pilot scheme for the much larger PERT control of the Concord SST programme; but it could do little to ease the problems of the engineers, who appreciated how much better the 221 could be made if additional money were available. For example, the original FD.2 cockpit was cramped even in comparison with other early supersonic aircraft, and when Godfrey Auty, chief test pilot of the BAC Filton Division, carried out func- tioning checks prior to the first flight he found that the addition of extra equipment further restricted the elbow room available. More- over, the cockpit layout and instrumentation of the FD.2 was planned a full ten years ago, and was hardly in keeping with modern standards. Of all the economy-minded decisions taken in the 221 conversion the most far-reaching was the elimination of systems test rigs. Major modifications to an aircraft invariably generate a chain reaction of system design-changes, and in turning the FD.2 into the 221 numerous major alterations to systems and equipment were in- escapable. For example, the taller undercarriage requires longer- stroke jacks drawing a greater amount of fluid from the hydraulic system, necessitating pressurizing the hydraulic tanks, which in- creased the system back-pressure and held out the spring-operated undercarriage locks. This type of progression was repeated in other parts of the aircraft systems. Absence of test rigs meant that all these modifications had to be made to aircraft standard and tested on the aircraft. The con- sequent protracted ground testing is responsible for the fact that the aircraft did not fly until May 1 of this year, ten months after the conversion was completed. To the Treasury, and Government departments in general, expenditure of time is more acceptable than expenditure of money, and the absence of system rigs was quite deliberate. In effecting the conversion the largest task was to design and build the new wing, and integrate it with the aircraft. The ogival delta surface was constructed in port and starboard halves offered up to the sides of the fuselage, and the majority of the root attach- ment fittings were those of the original wing. Area of the complete surface is some 500 sq ft, and the leading edge has a straight middle portion with a sweep angle of 65°, curving round to a streamwise tip. Thickness/chord ratio is 4.5 per cent. To ensure effective separation and vortex formation, the leading edge has a very small radius (i.e., it is sharp), and it is extended forwards in the form of a long chine along each side of the body to maintain vortex attach- ment. Like the FD.2, the new wing has outboard ailerons and inboard elevators, but the surfaces themselves are of greater chord and more rapid response rate. Experience may show that the ailerons and elevators should be coupled together as elevons, or that the ailerons should be coupled to-the rudder. In the wing the only concessions to the FD.2 ancestry are the unchanged locations of the wing pick-ups and the position of the elevator jacks inside the body. In general, the 221 wing has been constructed to tolerances tighter than those used in the FD.2 and more in keeping with modern Mach 2 aircraft; particular care has been taken to maintain a clean upper surface, so as not to interfere with the vortex. The underside, however, is broken up by the engine intakes and the big bulged fairings for the main landing gear and aileron power units. The original Fairey Delta 2, photographed at the 1955 SBAC display streaming its braking parachute
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