TRAJECTORY BEHAVIOUR OF A CONTROL CONFIGURED AIRCRAFT SUBJECTED TO RANDOM DISTURBANCES.

The longitudinal behavior of Boeing B. 747 transport aircraft with some of its original aerodynamic effectors operating as active controllers in addition to the conventional elevators was studied. The ailerons are collectively used as outboard active flaps, and the inboard section of the high-lift triple-slotted flaps are employed as model-following system in which the optimal feedback gains are computed to minimize the integral performance index. A lighter wing structure has been designed as the result of wing loads reduction, and further weight saving (reduced tail size) has been obtained by taking advantage of the beneficial effect of the active controller activity in reducing the elevator deflections required in the pull-up maneuver. Comparisons are made in the response characteristics of the original aircraft and in the optimal closed-loop active configurations subjected to continuous atmospheric turbulence. The results indicate that the various active configurations considered in the study differ appreciably in their trajectory-following precision.