It is safe to say that in no branch of applied science have the difficulties been greater or the process of development more rapid than in aeronautics. By far. the largest factor in the triumph of the aeroplane has been the improved internal combustion engine, a class of prime mover which, generating a maximum of power for a minimum of weight from concentrated fuel, is to-day such an outstanding engineering achievement as to arouse one's curiosity regarding its origin and development.

I cannot find better words, adequately to express my meaning, than those of John Farey (I) in his remarkable book, “On the Steam Engine,” published in 1827. Applying Farey's statement also to internal combustion as we know it, we might well say that in common with the steam engine, “It is an invention highly creditable to human genius and industry for it exhibits the most valuable application of philosophical principles to the arts of life and has produced greater and more general changes in the practice of mechanics than has ever been effected by any one invention in history.”

In presenting this paper on the producing of a prototype aircraft it is not the author's intention to deal with the overall conception of the type or such matters as operational requirements, performance, type of construction and so on, but rather to start from the point where the general arrangement of the aircraft has been drawn and to try to describe what, in his opinion, should be the best way to produce the aircraft in the shortest possible time and at the least possible cost.

Any theoretical attempt to evaluate the forces and couples experienced by an aircraft when in flight by a mathematical analysis of the pressures exerted by the air when in motion about the various parts, leads to what have, so far, proved insuperable difficulties. It involves the integration of the equations of motion of a real fluid, and, except in a few very special cases, these have been insoluble. The actual motion of a fluid is affected by a number of its properties, and, in general, accounts would have to be taken of its density, viscosity, and at high speeds its compressibility. In certain circumstances the effect of these last two can be neglected and the classical theory of hydrodynamics dealing with the motion of a non-viscous, incompressible or perfect fluid can be applied. A further simplification consists in supposing that the motion is irrotational, that is, any small portion of the fluid at a point has no angular velocity about its centre of gravity.

Progress of any organisation may be related either to an assumed basis within the organisation itself, or to some other organisations, preferably competitors in the same business. The second method is more realistic and by relating the corresponding data in ratios, it helps to eliminate to a great extent the influence of price changes, which distort yearly comparisons of revenues and expenses.

In the United States the trunk lines represent over 95 per cent. of the total revenue ton-miles flown on the domestic routes and in international aviation, the largest system with the highest quality of service. Therefore, by comparing in Part I the domestic services of Trans-Canada Air Lines (T.C.A.) to corresponding services of the U.S. trunk lines, the most severe criterion was chosen.

Part II contains an investigation of trends of particular expenses in relation to the total expenses for T.C.A's North American Services.