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Aviation History
1936
1936 - 0066.PDF
30 FLIGHT. JANUARY 9, 1936. steamer on alternate weeks. Now the mail service is to go by air every week, flying by night as well as day. When the Loire 102 flying boat comes into service she will have sleeping bunks for passengers. When this South Atlantic service is well established, announces Air France, the Company intends to turn its attention to the North Atlantic. Commercial Efficiency EFFICIENCY, in mechanics, is the ratio between that which is put into a machine and that which is taken out of it. The efficiency of aircraft can be of various kinds, not always conforming too well to the strict definition of the word. Thus the aero dynamic efficiency can be regarded as the ratio of lift to drag, the structural efficiency as the ratio of gross weight to tare weight, and so on. The commercial efficiency of aircraft is a quantity difficult to define concisely. Yet it is one which the operator needs to know in order to select the type of air craft which best suits his requirements. Unfortunately, any given aircraft may be very efficient for one kind of route and very inefficient for another, so that before efficiency can be assessed it is necessary to make all sorts of provisos. In this week's issue of Flight a contributor attempts to give a " figure of merit " intended to serve as a guide to operators in judging the relative "commercial effi ciency" of different aircraft. The factors which enter into his formula are the speed, the horse-power, the number of passengers, and the price. With this choice of factors few will probably disagree. They are the items which most affect what the Germans call the " pay ability " of an aircraft. Obviously, the faster a machine is for a given number of passengers and a given horse power, the more efficient it is; and the less it costs per passenger seat, the more economic it should be. Or, conversely, the smaller the horse-power for which a given number of passengers can be carried at a given speed, the greater the economy of operation. However, it does not seem by any means certain that our contributor has necessarily chosen the correct ex ponents for the different factors. For instance, drag or resistance varies as the square of the speed, and horse power varies as the cube of the speed. Fundamentally, therefore, one would expect the exponents of these two quantities to be something other than one. By choosing an exponent larger or smaller than one, greater or less weight would be placed on the particular item, which might be speed, or cost or horse-power. But perhaps our contributor assumes that operators are a little weak on powers and roots, and therefore prefers to use the plain figures. At least the formula has the merit of simplicity. A SERVICE RECORD : Figures recently issued by the Air Ministry show that the flying time of the machines engaged in the 1935 Air Exercises aggregated 3,830^ hours, which is an increase of 37 per cent, over the figures for 1934. High-altitude fighting was an outstanding feature, combats between light bombers and fighters being fought at about 21,000 ft. This photograph taken during the Exercises, shows such an engagement. The fighters are Furies and the picture was secured from a Gordon.
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