During the war, the rate of production which could be expected from an organisation setting out to manufacture a new type of aircraft was of great interest from the planning point of view. It was found that a time of the order of twelve to eighteen months elapsed between the delivery of the first production type and the achievement of the peak rate of production for which the factory was planned. This report analyses how this growth takes place and used the theoretical growth curve, known as the Logistics, for fitting smooth curves to a large amount of date from several countries. From the Logistic formula an index of the rate of growth for judging the relative performances in different projects has been evolved. Its use includes also the planning of production schedules. The factors determining the rate of growth are investigated but these would appear to be more in the intangible category rather than among the simple physical conditions such as size of programme or of aircraft.