Reducing fuel consumption of subsonic aircraft by optimal cyclic cruise

Fuel consumption in range and endurance flight is considered as an optimal cyclic control problem. In regard to range cruise, the incompressible and compressible flight regimes are treated separately because each of them shows specific effects for optimal cyclic flight. The improvements achievable in the incompressible flight regime depend on the admissible altitude range. For the compressible flight regime, it is shown that drag rise effects represent a key factor limiting the improvements possible by optimal cyclic cruise. Furthermore, results are presented for endurance flight, which is more improved by optimal cyclic control than is range cruise.