Computerized aircraft synthesis.

A concept and philosophy of computerized aircraft synthesis is discussed, and Computer Program SYNAC (SYNthesis of AirCraft) is examined in some detail by considering examples of both its construction and its application. An aircraft synthesis computer program involves three principal functions: determination of force characteristics, determination of aircraft performance, and configuration control. There are three groups of variables: independent configuration size and shape variables; intermediate weight-, propulsion-, and aerodynamic-force characteristics variables; and dependent performance variables. Program SYNAC is organized in seven major modules: input, configuration control, geometry, weight, propulsion, aerodynamics, and performance. The program yields accuracies comparable with conventional aircraft synthesis techniques. Computer time per problem is currently on the order of 1 min, and ultimate times of y - of a minute are expected. A typical application of Program SYNAC involves the maximum-range optimization (in terms of wing area, wing thickness ratio, wing aspect ratio, wing taper ratio, and engine size) of a variable wing-sweep configuration for an air-to-ground mission.