Prof. L. Bairstow, C.B.E., F.R.S.

Abstract

THE retirement of Prof. L. Bairstow from the post of Zaharoff professor of aeronautics in the University of London marks the departure of a pioneer from the scientific side of aviation. Bairstow began his work on aerodynamics so long ago as 1909. He was then on the scientific staff of the Engineering Department of the National Physical Laboratory, and when it was decided to undertake aerodynamic research in the Laboratory, he was charged with the formation of a small group of workers and the carrying out of research under the general control of the Advisory Committee for Aeronautics. He very quickly justified the confidence placed in him and began to lay the foundations of the new science. Seeing at once the fundamental importance to aerodynamics of the theory of dynamic similarity, he initiated experiments in air and water to prove its truth to the unbelieving. By 1911, he and his collaborators had made a number of investigations on wind tunnel design and had succeeded in producing what was the first really satisfactory wind tunnel in Britain. About the same time he was studying the theory of the stability of aeroplanes, as laid down by Bryan, which he extended very greatly as time went on and generalized to cover all six degrees of freedom. He employed the wind tunnel to measure aerodynamic stability derivatives, and by using the values so obtained in the light of the theory, he produced the first clear account of the disturbed motions of aircraft, and established the fundamental basis of all later developments in this field. He even traced the motion of an aeroplane as it flew through a prescribed gust. An example of his experimental versatility was an attempt to investigate the motions of airships by tests on models about six inches long in a water stream flowing at a few inches a second. He was responsible for the first investigation in Britain on the subject of flutter, and he contributed much to the knowledge of practical flying by his investigations of flying accidents. The Aerodynamics Division of the National Physical Laboratory, as it exists to-day, owes Prof. Bairstow an immense debt of gratitude for the work he did in establishing it. This work was recognized in 1917 by the award of the C.B.E., and by his election to the fellowship of the Royal Society.