I have chosen to describe the methods employed by the Research Division of the United States Navy Bureau of Aeronautics with the hope that others engaged in a similar line of endeavour may be able to make profitable use of this information in the solution of their specific problems. The development of the material to be discussed arose directly from the need for quick, reasonably accurate and simple means for studying a broad series of aircraft designs leading toward fulfilling an overall military requirement. This process is carried out in the Bureau of Aeronautics by the Research Division prior to the issuing of a type specification with a request for proposal to the various manufacturers. Before these specifications are decided upon, many designs must be investigated and reported to those initially responsible for the issuing of military requirements. By this process intelligent compromises are arrived at and the best possible aeroplane chosen. These compromises reflect the performance, the ability of operation from carriers, and the effectiveness of the design as a military weapon.