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Aviation History
1957
1957 - 1628.PDF
716 FLIGHT AIRLINERS OF THE WORLD ACCOUNTANT . . . POWERPLANT Rolls-Royce Dart R.Da6 Mark 512engines giving 1,730 e.h.p. for take-off are fitted in as standard an installation as possible (the standard being based on the Viscount).Immediate increases in take-off weight are not being sought, and the installation of more powerful Darts is not required to meettake-off performance requirements. Among the more functional differences in this installation are those affecting the 10ft diameterRotol propellers. The Dart reduction gear ratio has been altered to 0.107 and the ground fine pitch stop setting is 0 deg. The flightfine pitch stop is at 19£ deg. SYSTEMS Flying Controls These are a conventional all-pushrod system, only the trim controls being cable-operated. Control runs passing through the pressure cabin envelope do sowith a radial motion and are sealed by pressure boxes around the bearings. Reciprocating control rods—such as those passingthrough the wing roots—are sealed by long glands. The main engine controls are grouped on a central console—enlarged on aircraft subsequent to the prototype—on which are also placed trim, undercarriage and flap selector levers. The flightinstrument panel was laid out following the canvassing of pilot opinion as to the best arrangements. Access for maintenance andconversion to foreign standards is good. Fuel The system has been kept very simple. A 565 Imp. galcapacity integral tank in each wing outboard of the nacelles feeds its own engine, but a cross feed is also provided. A fuel boosterpump is installed on each spar in specially designed pump com- partments which enable pumps to be changed without first drain-ing off the fuel. Access to the tanks is through detachable manhole covers in the front spar web. The tank structure is sealed withoutrecourse to sealing strip; Bostick preparations are used through- out. Provision has been made for the optional installation ofadditional 80 gal bag tanks each side; the total fuel capacity is 1,280 Imp. gal. Inboard of the integral tanks are two bag tankseach containing 32 Imp. gal of water methanol which is injected at temperatures in excess of I.S.A. to maintain take-off power.The capacity is sufficient for six minutes' operations at I.S.A. + 30 deg C. Refuelling can be either by pressure through refuelling valves, or by gravity through an overwing refuelling cap. Smiths' Way- mouth gauges are employed for contents indication, and this system is used to establish the amount of fuel fed into the tanks by the refueller. The fuel capacity can also be checked by dipsticks. Cabin Air Fresh air (with no recirculation) is supplied byblowers, heat exchangers and a cold-air unit in the centre section. The cabin is pressurized to give 8,000ft cabin con-ditions at 25,000ft. Twelve complete changes of air are made per hour. A ground ventilation fan and filter can be included andthe standard ducting provides a connection for the use of an air conditioning ground service truck. Electric The electric system consists of a 28-V D.C. earthreturn system supplied by two 6 kW D.C. generators on the proto- type and 9 kW generators on production aircraft, one of which isdriven from each engine. Four 24-V 25 amp-hr batteries are fitted, one of which is the normal aircraft battery and three ofwhich are provided for emergency supply and engine starting if no external supplies are available. Engine and propeller de-icing power is provided by two 7.5 kVAthree-phase alternators; each engine de-icing load is supplied from its own alternator. Three rotary inverters supplying 115-V A.C.for flight instruments can be fitted to suit specific requirements. Hydraulic System Undercarriage and doors, flaps, brakes andnosewheel steering are operated on D.T.D. 585 oil supplied at 3,000 lb/sq in from two Lockheed Mk 9 pumps. An emergencyhand pump (also for ground testing) is fitted. A total of four accumulators are installed: one for the normal system, two toprovide normal and emergency wheel brake power and one used for emergency undercarriage lowering. The wheels are automatic-ally braked on selection of "undercarriage up." The flaps are operated by two Dowty jacks, one in each wing.Should one fail, sufficient power remains for partial operation, and a secondary system is provided in the charge of solenoid-operatedselectors by which flaps may be lowered with the handpump. Flight Deck Although the cockpit is fairly small, it hasadequate head room and width. Both pilots' seats are mounted on runners and slide back clear of the central pedestal to give ampleaccess to the seats. A direct vision panel in the windscreen slides back to give a wide angle of clear vision to the sides and ahead,and both wing tips can be seen from the cockpit. Mechanical windscreen wipers and anti-icing spray equipment are fitted. The layout of all cockpit equipment and instruments has beendesigned to generally accepted British standards, but it can—and would—be modified to suit the requirements of particularcustomers. In later aircraft a British or American weather radar scanner will be fitted behind a glass-fibre nose cap. The display tube will be mounted aft of the centre instrument panel. Radio The radio station is on the starboard side of the aircraftbehind the second pilot. Equipment is installed in standard S.B.A.C. racking in the prototype, but equipment and installationwill be fitted to customers' requirements on production aircraft. The prototype is fitted with dual V.H.F. transmitter/receivers, anA.D.F. receiver, I.L.S. equipment and crew intercommunication. PAYLOAD ACCOMMODATION The adaptability of theAccountant has resulted in a wide choice of interior arrangements being available. Typical versions are (a) an executive aircraft forranges of up to 2,000 miles with seats for eight or nine or alter- natively 18 passengers; (b) a 28-seat feeder liner with a wide reardoor for loading freight in a mixed passenger/freight configura- tion; (c) an all-freight version with a capacity of 1,670 cu ft;(d) a Mark 2 version with 40 seats. Discussions are now in train concerning Accountant production.If sufficient orders are obtained ("considerable overseas interest," particularly in the executive version, has been expressed), theaircraft might be built by a major aircraft group. The price of the Accountant has been given as £120,000 to £150,000, dependingupon the equipment installed. AVIATION TRADERS ACCOUNTANT Two Rolls-Royce Dart (512) turboprop* of 1,730 e.h.p. Dimensions: Span, 82ft 6in; overall length, 62ft 1 in: overall height, 25ft 3in;wing area, 632 sq ft; aspect ratio, 10.77; wing loading, 44.3 Ib/sq ft; total fuselage capacity, 1,670 cu ft.Weights: Initial gross weight, 28,500 Ib; initial max. landing weight, 27,100 Ib; zero fuel weight, 26,500 Ib; fuel, 1,280 Imp. gal.Performance: Maximum V.F.R. stage-length, 2,420 st. miles; max. V.M.C. stage with 28 passengers and luggage, 1,020 st. miles; operating altitude, 25,000ft;mean cruising speed, 295 m.p.h.; sea level balanced field length at 28,500 Ib I.S.A., 3,220ft; at I.S.A. + 15 deg C, 3,400ft; at I.S.A. and 5,000ft altitude, 4,000ft; rate ofclimb, sea level and I.S.A., 1,500ft;min; single-engine climb, 500ft min; time to 25,000ft (two engines), 27.6 min; stalling speed, 69 kt. Payload-range and direct operating costs for the Accountant at take-off weight of 28J00 Ib. Costs are to the S.B.A.C. Method. 200 400 600 800 1.000 1,200 1,400 1.600 1800 STAGE LENGTH (am.)
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