Development and flight evaluation of an augmented stability active controls concept with a small tail

Parasite drag reduction evaluation is composed of wind tunnel tests with a standard L-1011 tail and two reduced area tail configurations. Trim drag reduction is evaluated by rebalancing the airplane for relaxed static stability. This is accomplished by pumping water to tanks in the forward and aft of the airplane to acheive desired center of gravity location. Also, the L-1011 is modified to incorporate term and advanced augmented systems. By using advanced wings and aircraft relaxed static stability significant fuel savings can be realized. An airplane's dynamic stability becomes more sensitive for decreased tail size, relaxed static stability, and advanced wing configurations. Active control pitch augmentation will be used to acheive the required handling qualities. Flight tests will be performed to evaluate the pitch augmentation systems. The effect of elevator downrig on stabilizer/elevator hinge moments will be measured. For control system analysis, the normal acceleration feedback and pitch rate feedback are analyzed.