A PHYSICIST addressing an informal gathering recently was asked by one of his audience if lie could put Einstein's relativity theory in a nutshell. The task of covering in one short article the whole realm of problems which arise in the aerodynamic design of an aeroplane to‐day, though not so exacting, is still formidable. Fortunately a learned scientific thesis on every aspect, even were space available, is undesirable; for I am sure it will be agreed that a too meticulous or detailed study of even a few of the problems would only obscure the main issue, which is to discuss our present ideas on aeroplane design from the aerodynamic point of view and to indicate the direction in which they are likely to lead us.