Scheduling of control surfaces for aircraft performance optimisation

Two methods for scheduling the leading edge slat and optimizing lift-to-drag ratio (LDR) are compared. One method employs wind tunnel data on pitching moment, lift force, and drag force to obtain the LDR for assumed Mach number, slat position, and AOA while using an elevator setting that is taken as the trim setting for which the pitching moment is zero. The second method uses the complete 6-DOF simulation model and associated trim algorithm to generate the LDR for a given flight condition and aircraft configuration. The comparison shows that the second method is more realistic as well as simple. It is recommended that this technique be used to arrive at control surface schedules for optimal aircraft performance