The design of an aeroplane to achieve the greatest possible altitude is, from one aspect at least, a simple matter, because it is a case free largely from the compromises usually necessitated in the endeavour to meet best the operational requirements of a specification.

The starting off point must be the engine. I do not propose to touch the engine side of the problem, other than to regard the engine as an “ embodiment loan ” which has been made to the aeroplane designer and for which he has then to design an. aeroplane which shall achieve the greatest possible altitude when powered by this engine. Obviously, the main requirement from the engine is that it shall give the greatest possible b.h.p. per pound of its weight at very high altitudes. This means, of course, the highest possible supercharging and rather indicates the air-cooled radial engine because of the inherent low weight per b.h.p. of this type.