The present stage in the evolution of commercial aeroplanes brings questions of speed and load into prominence, and it is hoped that an attempt to look at these things from a designer's point of view may be justified.

An aeroplane at first glance might appear to be an uneconomical vehicle. It may have over 100 h.p. installed per passenger, and this gives an expensive impression. The other side of the picture is that aeroplanes can achieve over 60 passenger miles per gallon of petrol at a higher speed than any other form of transport.