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Aviation History
1951
1951 - 0361.PDF
23 February 1951 233 Logical grouping and the elimination of all that is unnecessary has led to a commendably simple and roomy cock- pit and, large as it is, the Ambassador can safely be fUmn solo. Experiences at the controls were described in detail in Flight of October 20th, 1949 (No. 33 of the "In the Air" series). This photograph shows that engine instru- ments (including two-needle r.pjn. and boost dials) are arranged on the central panel and that a full complement of blind-flying instruments is provided in front of each pilot, lined up across the top of the three main panels are the emergency controls and indicators, and the buttons and switches for ignition, priming, starting and slow-running cut- off. Carried on. the compact central pedestal are levers for power, airscrews and services and also the three " sensed " trimming wheels. occasions the damage to engines and nacelles has been less thanwould have occurred to a low-wing type. There seems evidence to suggest that a high-wing layout will usually suffer less than alow-wing type in such circumstances. Those who hare flown in the Ambassador prototypes of theB.EA. Elizabethans know how favourably they compare with other piston-engine types on the score of noise-level and generalvibration. From a flying point of view the Elizabethan has the feel of a "big aircraft" while retaining the comparativelysprightly characteristics of its smaller brethren. Performance-wise—as our American friends would say—theElizabethan will give B.E_A. an edge over most of its rivals. Initially, schedules and sector times will be based on a poweroutput of 1,150 b.h.p. per engine (50.7 per cent METO power and 42.6 per cent take-off power), which, at a mean weight of51,500 1b, pressurized at 20,000ft, offers a true air cruising speed of 259 m.pJi. (225 kt). To maintain schedule against head-winds or in the event of delayed departures, an increase in power of up to 1,300 b.h.p. per engine will be available, making possiblean increase of cruising speed up to 274 m.pJi. (238 kt) to main- tain punctuality. Later on, as more experience is gained withthe Bristol Centaurus 661 engines, these powers may be increased. In the meantime, the relatively low powers selectedshould ensure reliability while maintaining respectable cruising speeds. In fact, even at these low initial powers the Elizabethan is nearly as fast as its most modern competitors operated at their highest commercial cruising speeds. Proportionately, power for power, the Elizabethan will be more than 20 m.pJi. faster than the Coovair 240, which until now has set the pace for this class of airliner. In single-engine performance—with its important bearing on safety—the Elizabethan wffl show a substantial advance over any comparable type flying to-day. It sets new one-engine perform- ance standards for a "twin." It will offer for the first time areasonable rate of climb on one engine with the undercarriage down and, in addition, a performance with wheels retractedsignificantly better than that of earlier types. Finally, that fundamental—costs. In spite of the relativelyhigh prime cost of the Elizabethan compared with earlier and less complex aircraft, properly used it gives promise of becoming afar better commercial proposition than any of its forebears. An analysis of the Elizabethan on the London-Paris route, forinstance, shows that its specific operating cost for each capacity ton-mile flown is likely to be some 24 per cent less than that ofthe Viking when each is flown at the same utilization of 1,750 hours per annum. As shown on page 232 the Elizabethan hasalso a wide spread of sector distances over which its costs are nearly constant Thus, the best economic stage-length for theElizabethan is about 550 statute miles, but the specific cost is only some 10 per cent greater per C.T.M. at 1,000 miles or at350 miles. Quantitatively speaking, the operating costs of the Elizabethanover a 550-mile stage, and used at the rate of 2,000 hours per annum—and assuming a network such as that of B.EA. on theContinent of Europe—are estimated by us to work out approxi- mately as follows, the final-figures remaining to be determined inthe light of experience: — , . . Total Cost Variable Operatine ".-:•••' - ••:- ~:;rr"~ cast*Per annum £221,650 £126,400 Per flying hour ... £110.8 £63.2Per aircraft-mile 11.02 shillings 6-28 shillings Per capacity ton-mile .., 27.5 pence 15.7 pence * Cost directly proportional to number of hours flown and landings made. These figures are significant, of course, only in terms of therelative value of the £ sterling at the date at which the assess- ment is made. However, a widely known yardstick can be used In this 47/49-seoter layout for B.EA. the " fdurth-crew " seat is for a check-pilot, trainee or observer. 2nd PILOT/ NAVIGATOR An, CREW STEWARD COAT-SPACE ORTWO EXTRA SEATS DIPLOMATIC I RADIO BAGGAGE MAIL CAPTAiN OPERATOR 16O cu PASSENGERS' LADES' BAGGAGE STEWARDESS ENTRY TOILET 125 cu ft
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