The Mechanical Principles of the Aeroplane

Abstract

THE entry of Dr. Brodetsky into the ranks of workers on aeronautical topics marks an important development in the higher study of aerial navigation. Why the achievements of modern aviation have not from the outset been built up on a sub structure of purely abstract mathematical theory such as has arisen concomitantly with other branches of physics and engineering is difficult to understand. The behaviour of laminae and other bodies moving through a medium under assumed laws of resistance, whether artificially propelled or otherwise, opens up a vast collection of problems which might well have occupied the attention of mathematicians and been illustrated by experiments with models long before the evolution of the full-sized aeroplane. Instead of this being done, flying machines have been built, flown, wrecked, and their pilots killed, by designers who have not even fully appreciated such elementary facts as that when an aeroplane is moving with uniform velocity the forces acting on it must be in equilibrium, that three forces in equilibrium must meet in a point, that an aeroplane has six degrees of freedom, that stability and equilibrium are not the same thing, and so forth. Whether the Tarrant triplane could have been saved by a full appreciation on the part of its pilots of the validity of the equation of initial angular acceleration, Id²θ/dt² = M, or numerous aviators saved from death by a better knowledge of the forces and couples on which longitudinal and lateral stability depend, are debatable questions. Meanwhile mathe maticians of repute have attacked the writer of this review for intimating that a fuller theoretical study of the problem should be undertaken.

The Mechanical Principles of the Aeroplane.

By Dr. S. Brodetsky. Pp. vii + 272. (London: J. and A. Churchill, 1921.) 21s. net.