Importance

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Abstract

The present invention relates to an Active Control Surface Modal (ACSM) device that generates unsteady aerodynamic damping to alleviate aeroelastic structural instability, vibration and dynamic loads. An active control surface modal deformation is created by means of a pair of antagonistically activated actuators. Since the masses of upper and lower surface skins are lighter, the modal deformations can be activated at high frequencies that can encompass wide band spectrum of buffet, gust and flutter problem areas. An independent dosed loop active control system is used to activate the ACSM modes. Measured acceleration sensors are used as the feedback signals to compute the coefficients of the control law that is designed to suppress the dynamic environments such as buffet, gust and flutter. Then a computerized control system algorithm outputs a series of voltage signals that pass through power amplifiers to activate the actuators. Then the ACSM device generates unsteady aerodynamic damping in out-of-phase with the external (buffet/gust) or self excited air loads (flutter) to reduce or eliminate the undesirable dynamic effects on the aircraft. Some buffet analyses of a vertical tail, typical of a fighter aircraft, show 80 per cent reduction in peak stress, which amounts to an eight fold fatigue life extension of the vertical tail.

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First Claim