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Aviation History
1955
1955 - 0214.PDF
214 FLIGHT, 8 February1955 Fig. 6. Beryl-Meteor modified by the addition of under-nacelle jet pipes exhausting in a downward-and-rearward direction. Its minimum safe flying speed was reduced by 20 kt. This aircraft was built as a Mk 4 but now has a Mk 8 tail with auxiliary fins. TODAY'S RESEARCH FOR TOMORROW'S TRANSPORTS. .. entirely practicable. Such direct lift, so controlled, can, in prin-ciple, be used to reduce the lift required from the wing, so reduc- ing the minimum flying speed of the aircraft. In the extremecase it could reduce the distribution needed from the wing to zero, so that the aircraft can land and take-off vertically. Fig. 6 shows a Meteor aircraft which has been converted forexperimental use in investigating the downward deflection of the main propulsive jets. Plainly this type of installation can produceuseful effects only if the thrust of the propulsion engines is a substantial fraction of the weight of the aeroplane, a conditionto be found in military, rather than civil, aircraft. However, it illustrates another facet of the "machine generated lift" concept.In this aircraft, the propulsive jets can be deflected 60 deg down- wards, and the aircraft is capable of a stable minimum flying speedwhich is more than 20 kt lower than the standard type. The lecturer concluded this section of his paper by saying itwould be evident that the key to the practical application of these ideas was the availability of engines which were very light inweight in relation to the thrust they were capable of providing. We were now entering the stage of development of turbine engines TABLE IV: ANALYSIS OF FIRST Cruising speed Route Stage speed (still air) WingPowerplant ... ... ... Payload (Ib) ... ..; Number of passengers ... Take-off weight (Ib) COSTS AND DIRECT Present-day long range 230 kt 265 m.p.h.) London-Shan non-Gander-New York 213 kt (245 m.p.h.) StraightPiston 15,000 50 145.000 OPERATING COSTS High-Subsonic 478 kt (550 m.p.h.) London-New Yorkdirect 447 kt (510 m.p.h.) 35C sweptTurbojet (by-pass)35,000 120 239,000 First Costs (£) Equipped airframe Powerplant 350,000 80,000 800.000 145,000 when the gathering of these fruits of lightness could at least becontemplated. It would turn out, as usual, that the advantages could be taken either in terms of reduced approach and landingspeed or in terms of cruising economies, or in a combination of both. He returned to his plea that, in civil aviation, we shoulduse such advances to ensure the safety and reliability of the landing operation before going too far in gathering advantagesof other kinds. In the remaining part of the paper, to be summarized in Flightnext week, Sir Arnold discussed boundary-layer control; struc- tures; noise; navigation and communication; and problems ofbad-weather landing. APPENDIX I—OPERATING COSTSWhen operating costs are mentioned in the paper, they have been assessed using The Standard Method for the Estimation of DirectOperating Costs of Aircraft as evolved by the Society of British Aircraft Constructors. First costs have been estimated on the basis of £9 perpound of equipped airframe (basic operation weight less removable powerplant). Powerplant costs (turbojet) have been taken at £7 perpound of removable plant. Typical cost break-downs are shown in Table IV. The final costderived from such an analysis has been termed, in the main text, the "formula direct operating cost."The "in practice" addition mentioned in the main text allows for air- craft utilization shortfall, flight crew utilization shortfall, handling andmaintenance facilities at overseas stations and alternates, flying staff training, crews' expenses, overheads of engineering and fleet administra-tion, and provision of licences. The indirect cost element covers passenger services, station costs,commissions, sales, advertising and interest on capital (other than aircraft).In the case of "laminarized" aeroplanes, the extra weight of surface, suction equipment, ducts, etc., has been taken as 2 lb per square foot ofsurface laminarized. Airframe maintenance costs have been assumed to be 20 per cent above normal for 20 per cent drag reduction, and50 per cent above normal for 80 per cent drag reduction. The basic cost of airframe and equipment is taken to be the same for the laminaras for the non-laminar flow aeroplane. Direct Operating Costs (£) per Flying Hour Annual Obsolescence of Eqppd. airframe and spares ... Powerplant and spares Propeller and spares Insurance Total Maintenance and overhaul Airframe and equipment Powerplant Propellers Total Frying Cockpit crew Fuel Landing Total TOTAL 13 4 1 8 — 26 25 22 5 — 52 12 56 5 — 73 151 29 9 17 — 55 36 67 — 103 10 109 9 — 128 286 Unit Direct Operating Costs (Pence) in still air with 100% load factor Per nautical mile Per long ton nautical mile Per passenger nautical mile 171 24 2.4 153 10 0.95 ENGINES IN THE NEWST WO new gas-turbine power units have recently been in thenews. Of die first, only brief preliminary details are available; it is a new turbojet designed by the French S.N.E.C.M.A. groupin the 4,000 lb thrust class for use in fighters, missiles and coleop- ters [vertical-rising aircraft with annular aerofoils]. The firstprototype engine ran on the test bed at the end of December and the new unit is therefore contemporary with the Bristol Orpheusin both output and timing. The second new unit is the Allison 501 turboprop, now beingofered for delivery as a certificated transport unit in March 1957. The 501 is a commercial development of the T56 and has a 14-stage compressor (of no less than 9:1 pressure ratio), annular com- bustion chamber and four turbine stages all on the same shaft.The reduction gear is housed in a cast magnesium box carried forward of the power section to permit the intake to lie under thespinner. The gear ratio is 12.5 :1 in two stages. The engine drives a single 13ft 6in airscrew with three wide-chord blades. The 501 delivers up to 3,750 e.h.p. at sea level, with specificfuel consumption of the order of 0.54 lb/hr/e.h.p. The complete engine weighs only 1,610 lb and has a width and length of 27inand 145in, respectively. It is hoped that the overhaul life will be at 400 hr by the time the engine is ready for service in 1957.
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