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Aviation History
1961
1961 - 1084.PDF
FLIGHT, 10 August 1961 Frame stations and basic fuselage structure stem from the now generally accepted airline requirement for close-pitched passenger windows BAC One-Eleven . . . support Z-section stringers at approximately 5in pitch, flush- riveted to the skin. Hoop stresses are 9,8001b/sq in maximum. The doors are outward-opening on parallel linkage and are of the plug type. Systems Because of the high integrity demanded by short-hauloperations, with frequent take-off and landing, emphasis has been put on the choice of proven components with the widest airlineexperience. The forward fuselage underfloor area contains an equipment bay for electrical, radio and electronic equipment,separated from contamination by galley or toilet equipment. By duplication of the major system supplies the design provides thesafeguard of. mutual protection. Both halves of each system are normally in continuous operation, so that if one half fails the other half continues to provide for all essential services.With an eye on quick turn-round the designers of the One-Eleven have paid close attention to self-sufficiency on the ground; an a.p.u.is provided for ground conditioning, engine starting and operation of electrical systems without the use of external power. Flying controls Except for rudder control, which is power-assisted, the flying controls are manually operated by cables, main control surfaces being aerodynamically balanced and operated byspring tabs, Viscount-style. The tailplane is of adjustable incidence, operated by duplicated hydraulic motors. Lateral aileron control isassisted by hydraulically-operated spoilers which can also be used as airbrakes. The flaps are hydraulically-operated and are of thethree-piece Fowler type. BAC ONE-ELEVEN Two Rolls-Royce Spey 505-14 By-pass turbojet* of 10,4001b static thrust each Dimensions: Span, 88ft 6in, length, 92ft I in; height, 23ft 9in; wing area, 980 sq fc. Weights: Max ramp weight, 68,5501b; max take-off weight, 68,2501b (standard aircraft), 73,5001b (long-range version); max landing weight, 65,0001b; max zero fuel weight, 58.0001b; typical max payload, 14,0301b. Payload accommodation: Freight volume, 500 cu ft; cabin accommodational length, 58ft 9in (including amenities), 44ft 6in (seating area); max interior width, arm-rest height, IOft4in; seating accommodation, see diagrams on page 185. Fuel capacity: Max normal capacity, 2,250 Imp gal (2,700 US gal); optional addi- tional centre section tankage, 850 Imp gal (1,020 US gal). Performance: Max cruising speed, 540 m.p.h. (470kt) at 25,000ft; corresponding fuel consumption at 65,0001b all-up weight, 0.0875 nautical air miles/lb; max design speed, Mach 0.78; take-off field length, max t/o. weight (68,2501b) in standard condi- tions, 5,300ft (see also text); landing distance, with max payload and typical reserves at 62,0001b landing weight with a 60 per cent runway factor, 5,550ft; payload-range performance, see graph, page 184. Hydraulic system There are two completely independent systemsproviding a working maximum pressure of 3,0001b/sq in, each with its own reservoir. The system is designed for the use of Skydrol500A fire-resistant fluid. Pressure lines are of stainless steel and return lines of light alloy. Hydraulic power is used to operate thelanding gear, flaps, spoiler/airbrakes, tailplane-incidence, nose- wheel steering, ventral stairs, brakes, elevator feel, rudder boostand tail bumper. One system incorporates an electric pump which will ensure normal undercarriage retraction in the event of engineor pump failure during take-off. Fuel system Integral wing tankage accommodates 2,250 Imp gal (2,700 US gal). Provision is made also for a further 850 Imp gal (1,020 US gal) in the centre section. Electrical system Two Westinghouse constant-frequency a.c. generating channels are employed, the basic system comprising two constant-speed units driving 30Kva brushless generators which in turn supply two individual a.c. load bus-bars. The d.c. outputsare from two 150A rectifiers connected to a common d.c. bus- bar. Combined air system Compressor bleed air from each engine isled to a separate air system to provide airframe anti-icing and cabin air conditioning. Under normal circumstances cabin and flightdeck are each conditioned by a separate system, but in the event of an engine or system failure the remaining system can supply bothareas. Temperature control is provided by regulating the proportion of bleed air allowed to pass through the refrigeration system.Cabin pressure can be regulated up to a maximum of 71b/sq in. The twin air systems also supply hot air for anti-icing of the wing,tailplane and fin leading edges, and ensure that the ventral stairway remains free of ice. Either system will provide for the entire aircraftin the event of failure of one. Engine intakes are protected from ice by a separate engine compressor bleed. Payload accommodation The BAC One-Eleven is the first Britishairliner to have a rear ventral passenger door, which incorporates a hydraulically-operated stairway. There is also a conventional doorat the forward end of the fuselage, incorporating airsteps if re- quired. One advantage of the ventral door is that it wastes theleast internal cabin space. The maximum seating accommodation, five-abreast at 37in pitch, is 69, although it is believed that a 73-xeatversion is planned for BUA. The diagrams show the 69-seat all- economy layout, and a typical mixed-class version with 28 four-abreast first-class and 29 five-abreast economy-class seats. The One-Eleven is designed for maximum interior flexibilityto cater for a wide variety of passenger arrangements. This is facilitated by (1) constant and circular cross-section of the majorityof the 54ft of length available for accommodation, (2) track-mounted seats and bulkheads, and (3) a wide e.g. range. Interior width is124in at elbow level, which is 4Jin wider than the Viscount at its widest. The One-Eleven was designed from the outset with two-class operation in mind and there are separate passenger entries and separate amenity areas at each end of the cabin. The windows are vertical ellipses 14in x 9in and set at 20inpitch, giving approximately two windows per seat row. Door dimensions are 3ft 6in x 2ft 7in (forward) and 3ft 6in x 3ft 3Jin (aft).A total of 500 cu ft capacity is available for freight in two class D luggage holds, 320 cu ft forward and 180 cu ft aft with doorsrespectively 3ft X 2ft 7in and 3ft 1 in X 2ft. Powerplant The Rolls-Royce Spey 505-14 (a re-designation ofthe RB.163) is rated at 10,4001b static thrust. By-pass ratio is 1:1; pressure ratio, 16.7:1. Specific fuel consumption at a Mach numberof 0.78 at 25,000ft in ISA conditions, and using the maximum recommended cruising power, is 0.7761b/hr/lb. The engine wasdescribed in Flight for May 18, 1961. J.M. R. First British airliner with a rear ventral passenger entrance
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