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Aviation History
1945
1945 - 0892.PDF
492 FLIGHT MAY IOTH, 1945 heights, and with the aircraft travelling aj: something like 700ft. per sec. ? Suitable targets would be mani- fold. No factory—e-ven underground—no dockyard and no ship at sea would be safe from 15 tons of explosive arriving unheralded at any hour of the day or night. If the foregoing appears fantastic, remember this: When the D.H. Comet was produced in 1934 it was sug- gested that to form a super bomber force a number should be built, each to carry one 500 lb. bomb at 230 m.p.h. at 18,000ft. That suggestion was turned down, but the Mosquito—the direct development of the Comet —carrying a 4,000-pounder and nearly twice as fast, and at 30,000ft., has become one of the great weapons of this war. The degree of development required for this next step is no greater in scale than the difference between the Comet and the Mosquito. Cargo AircraftD ESIGNERS and operators alike will be interested in the very thorough study of cargo aircraft by Dr. Nebesar which we bring to a close in this issue. Starting with three engine sizes he limits the number of engines to two per aircraft and then examines' the relative efficiencies of three general groups of machines, evaluating the effects in each group of changes in wing loadings and power loadings, but. keeping the product of wing loading and power loading constant at the value of 300 suggested by Dr. Edward P. Warner. From an examination of these twelve aircraft, ranging in gross weight from 18,000 lb. to 105,000 lb., Dr. Nebesar arrives at the conclusion that not only the best load-carrying performance but also the greatest effi- ciency is achieved when the wing loading lies between 20 and 26 pounds per square foot and the corresponding power loading between 15 and 11.5 pounds per h.p. In this connection it is interesting to recall tjie-axrie4c on cargo aircraft hy Mr. W. S. Shackleton^publishedi our issues of February 8th and 15th igfj^his yearfr J^ the Bristol Freighter, type 170, ty/g»e the power loading as 12.8 pounds per CONTENTS The Outlook War in the Air - • - * - The Bombers' Record - - Here and There - Heinkel He 177 - - - - Swiss Planning .... Cargo Aircraft .... Grading the Amateur - In Spite of Difficulties - - Civil Aviation News - Correspondence - - - - Service Aviation .... 491 493 495 496 498 501 502 508 510 5" 513 514 wing loading as 21.3 pounds per square foot. Both these figures fall within Dr. Nebesar's- range. Another interesting feature of both Mr. Shackleton's article and Dr. Nebesar's study is their search for an '' efficiency factor'' relating to operating cost. The latter suggests that a combination of two previously suggested formulae would give a fair evaluation. At this point, however, the two studies cease to be strictly comparable, due to the- fact that in the United States petrol is cheap (Dr. Nebesar uses the value 15 cents per gallon), while in most other countries of the world it is a good deal more expensive. Thus, in any likely British aircraft intended for operation on Empire routes,, for instance, Dr. Nebesar's conclusions as to fuel cost would be likely to be far too low (he assumes it to be 25 per cent, of the total flying and operating cost for 500 miles' range.). Mr. Shackleton assumes a cost of is. 6d. per gallon, and in his estimate of operating costs of the Bristol Freighter e fuel cost works out at £5 5s. per hour, out of a total Operating cost of £18 6s. per hour, or nearly 29 per cent. Even the figure of is. 6d. per gallon is, in our inion, much too low. Petrol may be obtainable at that price on some routes, but we believe the average V$| good deal higher. CANCELLED CONTRACT: Derelict Me 109s in the much-bombed Focke-Wolf factory at Bremen. As the Luflwaffe supplyposition became worse and worse, aircraft repair and overhaul were carried out in any factory available.
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