The working principles and structural arrangements of several types of newly invented active flight control surfaces are detailed. The surfaces were built with graphite main spars around which mass-balanced aerodynamic shells were pivoted by active elements. These new designs used adaptive Flexspars to pitch the shells. Different actuator arrangements have yielded two main configurations: 1) the tip-joint Flexspar and 2) the shell-joint Flexspar. Estimations of aerodynamic shell pitch deflections are made using laminated plate theory and kinematics. The analytical estimations are compared to experimental test results which show static rotations in excess of +-11 deg on a 3.3" chord by 4" span Flexspar specimen. A comparison of pitch deflection performance shows that the tip-joint Flexspar generates the highest deflections on small-scale surfaces while older designs like the piezoelectric torque-plates are well suited to larger control surfaces. Wind tunnel data on several arrangements showed that static changes in C_L in excess of +-0.43 may be achieved with the tip-joint Flexspars. In addition to generating high pitch deflections, these actuators demonstrated stable, gust resistant responses in a series of flight tests on a free-flight remotely-piloted vehicle and on a 1/3 scale TOW missile wind tunnel model.
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