COMMERCIAL AIRCRAFT

New Zealand Herald, Volume LXXII, Issue 22107, 13 May 1935, Page 6

COMMERCIAL AIRCRAFT

QUESTIONS OF SPEEJ) POSSIBLE COMET VARIATIONS [from ottb own correspondent] By Air Mail LONDON. April 20 The view that high speed and commercial merit are compatible in the design of transport aeroplanes was expressed by Captain Geoffrey de Havilland, in a paper read before the Royal Aeronautical Society this week. He hinted at possible variations of the Comet racer design, such as won the Melbourne Centenary race, which might show excellent commercial qualities while retaining the speed of the original. He suggested that the Comet might be regarded as a scale model for a commercial aeroplane. "If the machine," he said, "was scaled up tc four times the power, that is, to 1800 maximum horse-power, the fuselage would hecome a commodious cabin without any alteration of proportions. Some loss in structure weight would be incurred, but there is something in hand in engine weight, and no doubt an outstanding high-speed aeroplane could be developed on these lines." Captain de Havilland based his opinion on the fact that pay-load decreases very roughly in proportion to increase in designed cruising speed, assuming that the aeroplanes included in any comparison have the same takeoff characteristics. Thus the commercial performance, as measured in tonmiles (the product of speed and payload) remains unaffected, and high speed becomes an asset for which no payment in lost ton-mileage is incurred. In other words, high speed can be designed for without increase of running costs, and would only be limited when the resulting high wing loadings caused trouble in getting into aerodromes. Aeroplanes were not uneconomical vehicles, he said, in that they achieved over 60 passenger-miles a gallon of fuel at a far higher speed than any other form of transport. Ho found no dis- . cernible departure from this criterion of commercial worth in aeroplanes capable of cruising speeds varying from under 100 miles an hour to more than 200 miles an hour, always assuming that the load carried was referred to the same take-off facility.