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Aviation History
1955
1955 - 1741.PDF
864 FLIGHT, 9 December 1955 EVOLUTION OF THE VANGUARD . . . passenger-carrying aircraft and, incidentally, large enough toadmit a complete Tyne powerplant. Fork-lift trucks will be rendered unnecessary by the low door-sills—4ft 8in from theground—and special provision will be made for pallet loading. The Vanguard wing will have a thin high-speed section withone or more spars (Vickers are not yet saying which) running from tip to tip. The structure of the wing is likely to be morelike the wings of jet bombers than of previous transports, owing to the relatively high wing loading and the high indicated flightspeeds for which the aircraft must be designed. The Mach per- formance of the wing (particularly in the dive case) is anotherfactor to be reckoned with, and characteristics in this respect will be better than those of fighters at the end of World War 2. Atypical cruising Mach number will be 0.6 and a good lift/drag ratio must be maintained throughout the cruising regime.Although the sectional lift coefficient begins to fall off on the inboard sections, it is worth noting that the Vanguard wing posi-tion gives the optimum form of wing/fuselage junction; a low wing, such as will be employed on the Electra, gives an adversejunction. Gross wing area will be 1,525 sq ft, the aspect ratio being almostexactly nine. The requirement for high cruising speed makes logical the choice of a high wing loading and, accordingly, the maximum attainable lift coefficient has been sought by fitting thegreatest possible area of highly effective flap. Tunnel testing has shown the Vanguard wing to have an outstanding performance;in fact, the approach speed at maximum landing weight will actually be lower than that for the Viscount in similar conditions.There is no reason to doubt that the new airliner will fully meet the B.E.A. requirement that it should be capable of operationout of all airfields through which the Corporation maintains ser- vices—even including Jersey, at reduced weight. Devices forartificially increasing circulation (such as flap blowing) have not been incorporated, but it is quite possible that such aids may bebrought in during the life of the design. All flying controls will be manually operated with aerodynamicboost. Evolution of the best control system is a necessarily lengthy task on so large and fast an aircraft with big control sur-faces, but Vickers seem confident that they will not run into serious trouble. It is appropriate to note that the latest reports ofthe Lockheed Electra (an aircraft comparable in size and per- formance), refer to a fully-powered control system, although theAmerican manufacturer originally intended to use a manual system with aerodynamic boost. The Vanguard tail design is conven-tional, although a considerable area of vertical surface is neces- sary to meet the asymmetric case at low airspeeds with suchpowerful engines. This raises a conflicting design problem since, although a high aspect ratio is desirable in order to obtain anaerodynamically efficient surface, it would be a severe handicap were the Vanguard to be too tall to go into B.E.A.'s engineeringbase—or, for that matter, in any hangar of any possible purchaser. Although some of the earlier Vickers studies would haveemployed bogie main undercarriage units, the final Vanguard undercarriage will have but four main wheels, two on each leg.Vickers are handling the design and manufacture of the gear themselves, as is their custom, and they have evolved an excep-tionally good layout for the new airliner. All units will retract hydraulically in a forward direction into bays covered by twindoors. Up-locks will be mechanical and emergency extension and locking will be provided by a free-fall fitting. An anti-skidbraking system will be fitted and the twin nose wheels will be hydraulically steerable. It is noteworthy that, in spite of thegreat maximum weight of the Vanguard, tyre pressure will not be high and the resultant large footprint will keep contact pressureand bending moments on concrete within the limits of all normal airfields. Fuel and Electricity ...-••• Fuel will be housed in integral wing tanks, with a pressure-fuelling coupling mounted roughly at head height from the ground. The integral fuel tanks within the large volume of thewing provide sufficient fuel capacity for all versions of the Vanguard at present contemplated. That a long-range Vanguardwill be developed is logical; it would not be tied to short field lengths and so could operate at considerably increased weight. Except for such equipment as electrical service panels, acces-sories in general are being kept out of the pressure hull. In particular, there will be no high-pressure hydraulic pipes in thepressurized region. The main electric power will be generated by four engine-driven 28-volt starter/generators. Alternating cur-rent power supplies for de-icing will be derived from four engine- driven alternators. The main hydraulic system for actuating flaps,undercarriage, nose-wheel steering and brakes will be from a common system working at 2,500-3,000 lb/sq in. A completelyself-contained hydraulic unit, which is off-load during taxi-ing and flight, will be provided for airstair operation. Engine starting will be electric, and die starting load will beno greater than that for the Viscount owing to the fact that only the high-pressure compressor of each engine need be driven. Com-prehensive de-icing systems will be standard, using hot air (from an air/exhaust-gas heat exchanger in two nacelles) on the wingand electro-thermal elements on the tail and airscrews. From the operator's point of view, the Vanguard should be excep-tionally well-planned and trouble-free, since it incorporates every lesson learned in Viscount operation in all parts of the world. It isno exaggeration to say that every appropriate section of B.E.A. has been consulted at every level about their new mainliner, andthe design also incorporates numerous requirements which haye been suggested by operators in several other countries. It willalso be a singularly self-sufficient transport needing no passenger steps or other ground services apart from fuel and possibly electricpower. As we have said, the design of the V.900 is now fixed in its(Concluded on page 880) Vanguard interiors: The upper impression is of the 93-seat version, the details showing the starboard seats at the rear of the cabin; a toilet; and the forward pantry, with a view into the main cabin. The lower illustration concerns the 76-seot aircraft, the details showing the passenger call-panel; the main pantry from the steward's seat, with the bar visible across the aisle to the left; and the starboard seating at the forward end of the main cabin.
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