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Aviation History
1955
1955 - 0880.PDF
60,0001b 40,0001b 30,0001b 20,000 Ib 10,000 Ib •>«— IV V. 610 up rated Da 1 — V.630 t WEIGI AXIM •f VlRST AKEO MAXI 00 EMP WEICr T WE MUM TY W HINC V.701 ICHT LANC LICHT i INC — r WEICr -- HT 1945 1946 1947 1948 1949 1950 1951 1952 195 1954 1955 Fig. 1. History of Viscount weight, 7945-55. Fig. 3. Dart progress: left, 27,000 hours of engine development (July 1947-March 1953); right, 350,000 hours of airline operations (July 1947-June 1955). WELLINGTON (248) LANCASTER (566) 047 R-ft (644) THE TURBOPROP IN PRACTICE . . . payload of 11,808 lb can be carried for a sector distance of 950statute miles, with full airline fuel reserves and allowances. Its maximum sector distance with full tanks works out at 1,230statute miles. Over this distance it can carry a payload of 9,858 lb, including 47 passengers, at a mean true air cruising speedof 321 m.p.h. at 21,500ft. For this, 940 e.h.p. is taken from each engine at 13,600 r.p.m. with a fuel consumption averaging 355U.S. gal/hr. These developed V.701A aircraft are now in service with B.E.A. and show improved economics in comparison with theoriginal V.701s at 57,000 lb a.u.w. Later production models go up to 62,000 lb. A break-down of the operating costs of the Viscount V.701 in51,500 hours of airline operation—including 47,000 take-offs and landings at a mean flight time of 2 hr 12 min—is set out inTable III. This shows that the total cost of engine and airscrew maintenance and overhaul—at $38.8 a flying hour—and 0.62 TABLE III: VISCOUNT V.701. B.E.A. AIRCRAFT ("A") (DIRECT) COSTS April 19th, 1953-May 31st, 1955; 51,500 revenue flying hours (25i months). Basic Annual Coits:— $ Amortization (10-year life) 2,853,760 Interest (at 4i per cent) 1,013,180 Insurance (at 2i per cent) 658,613 Total basic annual costs (for 25i months) $4,525,553 (per annum) $2,127,000 Hourly Cruising Costs:— Flying staff 1,920,299 Stewards 314,681 Fuel and oil 3,590,790 Engineering direct labour: Engines 34,544 Propellers 1,870 Airframe, etc 1,413,219 Materials: Engines 38,158 Propellers ... ... ... ... ... ... ... — Airframe, etc. 478,537 Outside contracts: Engines 1,608,351 Propellers 309,560 Airframe, etc 575,383 Total hourly cruising costs (for 25i months) $10,285,392 (per flying hour) $199.8 Landing Costs:— Landing fees (for 25i months) $569,688 (per landing) $24.21 Summary:— Total aircraft ("A") costs "\ f$15,380,633 Total revenue earned >for 25i months < $29,797,908 Revenue surplus on "A" costs J (, $14,417,295 Total aircraft costs per flying hour $299.5 Total aircraft costs per revenue mile $1,341 N.B.—These costs are representative of European prices and conditions. Costs under U.S. conditions appear to run some 30 per cent less. 12000 878 FLIGHT injOOO Fig. 2. Viscount payload develop- ment, 1948 to 1955 (right), and 1955 to 1958 (below). OBflOO a ,6000 4.000 2000 V.7oU(6(M)00lb.i955) s - 200 400 600 800 1JDO0 1200 1.400 SECTOR DISTANCE (st. miles) fa I 1 X 14.000 12000 10.000 WOO 6.000 4000 2000 200 400 600 BOO 1.000 1,200 1.400 1600 L800 SECTOR DISTANCE (st.mi Its) cents per take-off horsepower hour—has mounted to 13 per centof the total aircraft (direct) costs during the first two years of the Viscounts' life with B.E.A. This figure has recently beensubstantially reduced after the initial "learning period," and the teething troubles inevitable with a new vehicle.B.E.A.'s experience of the Viscount [Mr. Masefield continued] is sufficient to lead us clearly to the policy view that we shall notbuy any new major type of aeroplane with piston engines. We believe also that, throughout the foreseeable future, developedpropeller-turbines will serve our particular needs better than would either any form of piston engine or turbojet. Our con-clusion is based on some detailed analyses of projected aircraft designs which bracket sizes from 20 to 100 passenger seats andcruising speeds from 190 to 510 m.p.h. [Before discussing, against the background of B.E.A.'s experience withthe Viscount, their outlook towards future types and the progress expected from them, the lecturer surveyed the conception and develop-ment of the aircraft "to set both a pattern and a time scale for the future." The history of the Viscount was further dealt with in anextremely informative appendix to the lecture proper, and this we hope to publish in a subsequent issue of "Flight."] The Dart.—By the time B.E.A. put its first V.701 into com-mercial service a total of 21,000 engine hours had been built up, of which 13,624 were in the air (3,800 of these early flying hourswere accumulated in two Dart-Dakota airframes during 1951). These early airline hours with the DC-3 proved an invaluablecontribution to later success. They made possible the elimina- tion of early teething troubles, particularly on reduction gears andde-icing. Since 1946 [Mr. Masefield's paper continued] the Dart hasbeen steadily developed and it has now built up more than 350,000 hours of airline service, of which 225,000 have beenwith B.E.A. The engine has, in fact, advanced from the 1,000 h.p. of the original project to the 2,750 h.p. of future promise—all inthe course of ten years (Fig. 4). A record of the various versions of the Dart during this time is set out in Table IV.The heart of any aeroplane is its engines; its performance, its reliability, its operating cost and its passenger appeal stem funda-mentally from the characteristics of its power units. In the Dart we have an engine which is offering in the Viscount a relativelyhigh performance combined with excellent maintenance charac- teristics, good economy and great passenger-appeal. Although theDart remains, in conception, a 1945 engine—significantly inferior to what could be achieved from a new approach today—it nowhas the unique attraction of combining the fundamental virtues of a turboprop with a background wealth of airline operatingexperience. Naturally there have been teething troubles—in fact, in one 48-hour period we changed more than 40 engines touncover a suspected defect.
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