Giant Aeroplanes and their Design

Abstract

THE giant aeroplane has always influenced the mind of the engineer as well as of the layman in a manner altogether out of any proportion to its practicability. Like all other structures, animal or mechanical, it is subject to the inexorable law of Nature known to engineers as the ‘law of the cube’. For an established design of aeroplane with materials of unchanged quality, the law of the cube is not seriously disputed. If the proportion of useful load is plotted against surface and engine power, a well-defined family of closed isobars is obtained shrinking to a conjugate point of maximum useful load. For a braced biplane of wood with a factor of safety of 4 to 5, five tons total was a reasonable limit in pre-War days. An accumulation of detail improvements has put up this figure to seven or eight tons total weight, the disposable weight. including fuel, being about two-fifths of the total weight, and the paying load for five or six hours flight being roughly one-fifth.