The application of scientific principles to the design of aircraft and aircraft equipment during the post–war years has yielded results which are becoming increasingly apparent. The time interval which elapses between the conception of an idea and its application to production aircraft is necessarily long, but it would seem that we are just commencing to reap the reward of much patient study.

An attempt will be made to present a picture of the progress which has recently been made and to indicate the lines along which further research would appear most profitable. In making this review it is inevitable that attention should be paid particularly to Service aircraft. The more difficult the problem the greater is the ingenuity required to solve it, and the ever increasing demands made upon the designers of Service aircraft have stimulated research to perhaps a greater extent than is the case with civil aircraft, the requirements for which are less complex.