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Aviation History
1957
1957 - 0325.PDF
FLIGHT, 15 March 1957 327 A.W. 650 PHILOSOPHY . . . outside companies. All major sub-contractors are helping with acertain amount of credit, in that payment for at least one set of prototype components will not be requested until sales of the finalaircraft have started. Chief of the sub-contractors is, of course, Rolls-Royce whoseDart RDa.7/2 of 2,100 e.h.p. is matched with a Rotol propeller of lift 6in diameter. Sir George Edwards, of Vickers-Armstrongs,agreed to let Armstrong Whitworth buy Viscount-type powerplants complete back to the fireproof bulkhead. This installation alreadyhas a full British and American C. of A. and should save A.W .A. many months. The undercarriage is being bought from a specia-list firm and in geometry the main units are Chinese copies of those for the Friendship (but on a larger scale). During the preliminary design it was found that the optimumwing was almost coincident in outer form with that of the Avro Shackleton Mk 3. After carefully evaluating the whole picture,it was eventually decided to place much of the responsibility for the wing with Avro, to use the Shackleton 3 design as a basisand, as far as possible, to employ the existing jigs, tooling and established methods of the Manchester plant. Fatigue experiencewith this wing is very great, and the safe life can be predicted with confidence (in normal operation it is placed well beyond 30,000 hr).The final A.W. 650 wing is now much modified from that of the Shackleton; it has quite a different form of stress distribution,provision is made for the tail-boom attachments, the engine spacing is different, thermal anti-icing is standard and high-lift,double-slotted flaps are fitted. Choice of the latter type of flap may, in the distant future, give way to blown flaps, although thelatter would require an auxiliary source of air such as a Rover or a Blackburn-Turbomeca gas turbine. Final design of the complete tail unit is being undertaken in thedrawing office of the sister company of Gloster Aircraft. The tail is supported on long monocoque booms of roughly oval sectionextending from the rear of the inboard engine nacelles. Early in Utilising virtually identical wing, tail, powerplants and landing gear, the A.W. 650 (left) and A.W. 670 (lower left) are but two members of a versatile family. Both will be cleared to operate at around 82,000 Ib, and the former promises to have a D.O.C. of about Id per 2,000-lb statute mile. New weight data are: basic equipped, 39fl00 Ib; max. landing, 73,000 Ib; and zero-fuel, 70,000 Ib. Max. payload is 28,000 Ib. the life of the design rumours were current to the effect thatFairchild had experienced considerable structural trouble with such an arrangement; but discussions with the American manu-facturer convinced Armstrong Whitworth that, provided the air- frame was properly designed, twin booms could be employed withcomplete assurance and at a reasonable weight. Discussions were also held with Nord, whose Noratlas employs a similar configura-tion. The French company were found to employ coincident stress methods and to have achieved complete structural success. A very extensive test-programme, considerably in excess of thatrequired to satisfy the A.R.B., is already in hand to prove the structure and systems of the A.W. 650. In the basic analysis ofthe airframe one digital computer and two analogue computers are being employed. The digital machine is a Ferranti Pegasus andit is being fully utilized in performance analysis and structural work, and programming for the normal-mode investigations iscurrently taking place. One of the analogue (Avro) computers is at work on flutter; the other is a response simulator working onall kinds of dynamic flight problems, including pilot-initiated manoeuvres and landing cases. Two water tanks are being builtat the company's design centre at Whitley for fuselage testing and for a fatigue investigation on a complete airframe. Static testsof the wing will be undertaken by Avro. In addition to the two airframe test-shells, work is currentlyin hand on three prototypes which are scheduled to fly in October 1958, December 1958 and February 1959. Between April 1959and March I960, seven pre-production A.W. 650s will follow. This may seem a prodigal expenditure of company finance, but—in the words of the chairman of Rolls-Royce—Armstrong Whit- worth are "planning for success"—which is, of course, the logicalthing to do. The ultimate aim is to make available a fully certificated aeroplane at the earliest possible moment. At presentthe firm are slighdy ahead of schedule. While visiting the company we inspected the first mock-up atBaginton. Provision for radar is to be made in die centre of the hinging nose, which will also accommodate a crew-toilet and alarge baggage compartment. Up the stairs to the flight deck one finds what promises to be a conventional and very pleasant cockpit.Normally the aircraft will be flown by a crew of two, although provision is made for three, and the aircraft can be ferried solo.The only roof panel is that for radio, which occupies a small area on the centre-line. Specified equipment includes the SmithsFlight System and S.E.P.2 autopilot. Commercial success seems certain for both the A.W. 650 andthe military A.W. 660, and the high-capacity derivatives also seem assured of a small but important market. The machine is beingmarketed by the complete Hawker Siddeley Group, and the great sales-organization of Rolls-Royce is also likely to be of no smallassistance. It is far too early to start discussing particular sales- prospects, but it may be wordi recording that the 1/12-scale modelof the machine which is to be exhibited at the forthcoming Paris Salon will include all three types of fuselage, and that the A.W. 650fuselage will be finished in the markings of one airline and the A.W. 670 will bear the livery of another. On entering the A.W. 650 mock-up the width of hold becomes very apparent (the maximum is 140in). The flat roof is caused not by the wing but by the flight deck floor. This view is looking forward.
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