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Aviation History
1957
1957 - 1612.PDF
700 AIRLINERS OF THE WORLD COMET 4 and 4B wheel steering. Normal pressure is 2,500 lb/sq in. The system comprises four separate circuits, where necessary with inde- pendent reservoirs and hydraulic accumulators, with a colour code as follows:— Green: Serves undercarriage retraction, nosewheel steering,flaps, speed brakes, and wheel brakes; provides stand-by power for the flying controls; and is supplied by two pumps, one drivenby the port inner and die other by the starboard outer engine. Blue: Serves primary flying controls only, and is supplied bytwo pumps, one driven by the starboard inner engine and the other by the port outer engine.Red: Provides emergency operation of the undercarriage flaps and wheel-brakes through independent lines, being supplied byan electrically driven hydraulic pump. A hand pump in this cir- cuit provides a final emergency method of lowering the under-carriage. Yellow: Second emergency supply for the flying controls(operating the secondary servo unit rams through separate lines) supplied by an electrically driven pump. Electrics Electrical power is supplied by four engine-driven14kVA alternators, each with a continuous rectified output of 350 amp maintained at 28 V. Six 24 V, 25 amr>-hr batteries areinstalled. Five of the batteries are connected in series with a switch for internal engine starting. Power distribution is from asingle busbar which in the event of failure automatically splits into two parts, services being maintained by the good part.Inverter sets provide A.C. at 115v 400 c/s, 3-phase, for auxiliary power and at 26 V 400 c/s single-phase via transformers. FLIGHT DECK Although it is unlikely that Cometoperators will use five crew members, a typical arrangement of the control cabin provides for captain, first officer, engineer,radio officer, and navigator. The pilot's instruments are grouped into three main panels: flight panel, laid out in conformity withcurrent flight instrument standards, for each pilot, with a panel in between on which are grouped the engine instruments. Betweenthe two pilots is a floor-mounted control pedestal incorporating throttles, trimmers, flap control, speed brake control, under-carriage retraction and autopilot controls, and high-pressure and low-pressure engine fuel controls. The engineer has a stationto himself with a comprehensive panel arranged system by system to permit full control and observation of the aircraft systems.The radio navigation station has a spacious chart table and generous stowage room. The type of radio and radar equipment is variable accordingto requirements, and a wide flexibility of choice is available. H.F. communication is by either duplicated transmitters andtunable receivers, or by duplicated transceivers. V.H.F. com- munication is by duplicated transceivers or by duplicated trans-mitters with the receiver as a section of I.L.S./V.O.R. receiver. Duplicated A.D.F. is provided, and I.L.S. and V.O.R. equipmentmay be arranged to operate combined or as separate units; provi- sion is also made for Loran and D.M.E. (1,000 Mc/s or 200Mc/s), and an airborne search radar scanner is located in the nose. Aerials are of the suppressed type where possible, with the notableexception of the two H.F. line aerials. PAYLOAD ACCOMMODATION The Comet's pas-senger cabin is in two parts: a forward cabin about 25ft in length (Comet 4) and about 31ft in length (Comet 4B). The rear cabinin both versions is about 30ft in length. The two portions of the cabin are separated by a structural bulkhead in line with themain wing spars. Width and headroom are constant at 9ft and 6|ft respectively. Chairs are mounted on 31.7in tracks permittingdifferent arrangements to be achieved easily. Passengers enter via a door on the aft port side measuring 56inby 30in. Seven emergency escape exits are provided in the Comet 4 and ten in the Comet 4B. Common to both versions are theemergency door opposite the main entry door, and the crew door. In addition, the Comet 4 has four removable windowhatches and the Comet 4B has six removable window hatches. The Comet 4B has an escape hatch in the flight deck roof for thecrew. Each version has three freight holds, two under the floor, oneforward of the centre section (160 cu ft Comet 4 and about 200 cu ft Comet 4B) and the other aft (230 cu ft each version). The thirdfreight hold, varying in volumetric capacity according to the pas- senger accommodation provided, but with a maximum capacity ofabout 200 cu ft, is situated at the extreme aft end of the pres- surized cabin and is accessible via its own freight door on the star-board side of the fuselage. Comet 4 Layouts A typical first-class four-abreast layoutaccommodates 56-60 passengers. Alternative plans are available to seat 67 mixed-class and 76 tourist passengers. There is a widechoice, according to customer's requirements, regarding the loca- tion of lounges, galley, carry-on luggage compartments, and FLIGHT, 1 November 1957 toilets. For example, the 56-seat first-class arrangement has fourtoilets each with a washroom; a galley (situated on either side of the aft starboard side emergency exit door) with a second galleyat the forward end of the cabin just aft of the flight deck. Comet 4B Layouts A typical first-class four-abreast arrange-ment seats 84. This does not include the accommodation pro- vided in a luxurious lounge seating up to 8 people, which isdesigned to be installed in the most forward (and quietest) part of the cabin. Two toilets and a wardrobe and a galley areinstalled at the aft end of the cabin. The mixed-class arrange- ment accommodates 90 (40 first-class and 50 tourist) with threetoilets and a galley and two wardrobes. The all-tourist arrange- ment accommodates 99, mainly five abreast, and offers the facilityof the eight-seat lounge—unique in a tourist airliner. COMMERCIAL HISTORY The Comet formula was con-ceived in 1946, and applied to public service in May 1952. After the suspension of services in 1954, following the two Comet 1accidents, and applying the new structural knowledge gained as a result, de Havilland concentrated upon the development of theComet 4. This Rolls-Royce-powered version had twice the power and almost twice the capacity of the early Ghost-powered Comet 1.B.O.A.C. placed an order for 19 in February 1955. In July 1956, a development of the Comet 4, the 4A, wasannounced. This new Comet version had been designed to the requirements of Capital Airlines of America, who ordered a fleetof ten for delivery starting in June 1959 (Capital also ordered four interim Comet 4s—to be returned when the 4A fleet hadbeen built up—for delivery starting in November 1958 to permit the start of US domestic jet services in January 1959.) ButCapital's Comet order was deferred in May of this year due to the airline's financial difficulties, and the 4A—a stepping stonebetween the 4 and the 4B—may now be considered extinct. If Capital reinstate their Comet order (notwithstanding recentreports from the U.S. that the Comet contract has in fact now been cancelled) the Comet 4B would be the version considered. The first order for the 4B came from B.E.A., when in Septem-ber last a fleet of six was ordered by the Corporation for delivery in 1959. The Corporation bought the 4B to maintain its competi-tive position until the projected "ideal" short-haul jet becomes available in 1963 (see Projects, page 722). Although not part of the Comet's commercial history, exceptin the development it represents, it must be recorded that in June 1957 R.A.F. Transport Command's squadron of ten Comet2s reached full strength, having been formed 12 months before. At the time of writing, a total of 7,000 hr had been flown onscheduled services to Australia and on special R.A.F. services all over the world. In September last, B.O.A.C-'s Comet Unit resumed the opera-tions suspended in 1954 when a Comet 2E, one of two now operated by the Corporation, started a high-intensity programmeof daily flights between London and Beirut. Their purpose is to amass hours on the RA.29 engine of the Comet 4 and 4B; twoare installed in each Comet 2E in the outboard positions. To date some 550 hr have been flown on these non-passenger develop-ment flights. It is intended to amass 10,000 RA.29 engine hours on 2Es, the prototype 3 and production 4s before services startin 1959. About 4,000 hr will have been recorded by Caravelles. When B.O.A.C.'s Comet 4s enter service late next year theywill have behind them quite a formidable record of development. Although specific target dates are not available, present plansare for the first production Comet 4 to fly "early in 1958," and for certification and delivery to be achieved by "the latter half' of1958. B.O.A.C. plan to start services "before the end of 1958." The programme for the Comet 4B is for first flight in "late 1958,"and for delivery to B.E.A. to begin "towards the end of 1959." B.E.A. expect to begin 4B services in 1960. COMET 4 Four Rolls-Royce Avon RA.29 of 10,500 Ib static thrust each Dimensions: Span, 115ft; length, 111ft 6in; wing area, 2,121 sq ft; height' 28ft 6in. Weights: Max. take-off weight, 152,500 Ib; max. landing weight, 113,000 Ib; max. zero fuel weight, 92,000 Ib; equipped tare weight, 68,400 Ib (58 seats), 68,685 Ib (76 seats); capacity payload (58 seats first-class), 16,400 Ib; capacity payload (76 seats tourist-class), 19.300 Ib. Performance: Take-off field length, sea level, standard conditions, max. weight, 6,380ft; landing field length, standard conditions, max. landing weight, without reverse thrust, 6,200ft; payload-range performance, see graph; typical cruising speed in standard condition, 506 m.p.h.; cruising altitude, long-range technique, 38,000 ft. COMET 4B Four Rolls-Royce Avon RA.29 of 10,500 Ib static thrust each Dimensions: Span, 107ft 10in; length, 118ft; wing area, 2,066 sq ft; height, 28ft 6in. Weights: Max. take-off weight, 152,500 Ib; max. landing weight, 113,000 Ib; max. zero fuel weight, 98,500 Ib; equipped tare weight, 73,755 Ib (84 seats), 73,846 Ib (99 seats), 73,789 Ib (84 mixed-class seats); capacity payload, including freight (84 seats first-class), 19,680 Ib, (99 seats tourist-class), 22,280 Ib, (84 seats mixed-class), 21,624 Ib. Performance: Take-off field length, sea level, standard conditions, max. weight, 6,500ft; landing field length, standard conditions, max. landing weight, without reverse thrust, 6,260ft; payload-range performance, see graph; typical cruising speeds, 520 m.p.h. to 545 m.p.h. (depending on temperature); optimum cruising altitude (high-speed cruising technique), 23,500ft.
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