All-moving active aerodynamic surface research

Abstract

The structural and aerodynamic characteristics of a new class of active flight control surface are presented. This new type of surface uses a symmetric, subsonic aerodynamic shell which is supported at the quarter-chord by a main spar and actively pitched by an adaptive torque-plate. The structural mechanics of the torque-plate and several actuator elements are detailed, including newly invented interdigitated electrode (IDE) and constrained directionally attached piezoelectric (CDAP) elements. Laminated plate models demonstrate that both generate similar deflections with comparable torsional stiffness. An experimental torque-plate specimen constructed from PSI-5A-S2 piezoceramic shows high torsional deflections and stiffness as well as excellent correlation with theory. The constrained torque-plate was integrated into a 12.5 cm span *5 cm chord adaptive missile fin which was designed for Mach 0.6 flight under standard conditions. The specimen showed static pitch deflections up to +or-8.1 degrees and dynamic deflections of +or-19 degrees at resonance. The active surface was also wind tunnel tested up to 40 m s-1 and demonstrated invariant pitch deflections as a function of airspeed, a steady break frequency of 50 Hz, no flutter, buffet or divergence tendencies and steady lift coefficient changes up to +or-0.51.