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Aviation History
1957
1957 - 0324.PDF
326 FLIGHT, 15 March 1957 A.W. 650 Philosophy The Background and Current Progress of a Promising Civil I Military Transport Grouped around a display model are, I. to r..° D. A. Woodley, asst. chief designer (tech.); D. L. Raffle, chief performance engineer; R. Dean, asst. chief designer (projects); E. D. Keen, chief designer; H. J. Staite, chief re- search engineer; A. J. Troughton, chief structural and mechanical engineer; and H. F. Butler, A.W. 650 project designer. 1AST week we were invited by Sir W. G. Armstrong Whit-worth Aircraft, Ltd., to discuss the A.W. 650 transportJ project with several of the company's engineers who are responsible for its development. The 650 (a full introductoryaccount and basic description of which was published in our issue of January 18) is undoubtedly one of the most important transportaircraft projects in the world, and the design offers a number of substantial advantages which should ensure its commercial success. Its history dates from the autumn of 1955 when ArmstrongWhitworth were invited to submit (as a secret project) a study for a multi-purpose military transport aircraft. Bearing in mind thefact that such a machine would be likely to have civil applications, the firm were asked what contribution they would be prepared tomake towards the costs of development. In order to obtain a rough appraisal of the commercial prospects of such a machine,the chief performance engineer, Mr. D. L. Raffle, and Mr. B. P. Hough of the sales director's staff, undertook a quick sales-tour.At this time the studies were designated A.W. 66 (military) and 65 (civil), and they specified twin 3,000 h.p. turboprops and aconventional (i.e., not twin-boom) configuration. Conferences were held with the Ministry of Supply, and theentire project was finally turned over to the Ministry of Transport and Civil Aviation and to the company itself, and it has, sincethat time, been regarded principally as a civil programme with military applications, rather than vice versa. With the backingof the Hawker Siddeley Group the company took the bold step of undertaking the entire design, manufacture, development andinitial production as a private venture. They have decided to go ahead along the lines which diey feel will produce the best resultsand will then offer one or more military equivalents of the finalized civil aeroplane. Armstrong Whitworth accordingly undertook an extensivemarket-survey study in order to determine the correct powerplant, cross-section of hold for maximum flexibility, payload/rangediagram and other fundamentals. As a result the hold was widened and lowered, and the whole aircraft was reappraised to fit it forthe widest possible market. At the outset, of course, it was essential to decide whether to use two big engines or four small ones. Choice of engine isfundamental to success in the civil field, and it was soon firmly decided that initial selection of a thoroughly well-tried and reliableunit must be a back-marker of the entire programme. The Dart was thereupon chosen and the project was redesignated A.W. 650.The Dart is considered io be the optimum engine by the vast majority of the possible customers to whom Armstrong Whitworthhave spoken. For long-range operation, and under a variety of special conditions, the twin-engined machine is more attractive,and the A.W. 651 has been planned with two Rolls-Royce Tynes. As we described in the issue mentioned above, the basic machinehas a pressurized fuselage of roughly circular section offering unobstructed volume for all kinds of useful load. There was littleunanimity among operators on the score of loading arrangements, but, following a strong lead from British independents, it wasdecided to provide straight-through loading at both ends by cut- ting off each end of the hull and leaving a simple circular sealbetween the fuselage proper and the single (not clam-shell) hinged end-doors. Nevertheless, die optimum fuselage for one operatorwas soon found to be quite incorrect for another, and before many months had passed the A.W. 650 had branched out into a familyof aeroplanes each matched to a particular type of operation. It seems to have been a sound move to adopt the twin-boom con-figuration, with the main undercarriage retracting into the booms. This has allowed the tail/boom/wing/powerplant combination toform a basic carrying vehicle for at least three distinct fuselages. For example, the basic military machines are the A.W. 660(four Darts) and 661 (two Tynes) both of which have an integral ramp at the rear for dropping ef heavy stores. Another design isthe A.W. 670 car-ferry, with an unpressurized double-deck fuselage of tremendous proportions, and the related A.W. 671 short-rangebus intended for high-payload operation over short stages and seating some 130 passengers in quadruple seat units on each sideof a central aisle. At present, however, the main task is the development of thebasic A.W. 650 as depicted in the upper drawing (p. 327). In many senses it is a co-operative project between Armstrong Whitworth,the remainder of the Hawker Siddeley Group and a number of As yet uncompleted, the first mock-up (wood skeleton and metal skin) is already impressive. The pressurized region behind the flight deck will house systems components and will be faired neatly into the wing.
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