Active Suppression of Aeroelastic Instabilities for Forward Swept Wings.
Final rept. Jan 82-Dec 83,
AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH
Pagination or Media Count:
Analytical studies are conducted to investigate the potential of using active feedback control systems for preventing multiple aeroelastic instabilities in close proximity from occurring within the flight envelope of an advanced forward swept wing aircraft. With the addition of wing mounted external stores, the classical bendingtorsion flutter instability is driven to lower airspeeds into the vicinity of the aeroelastic instabilities more commonly associated with a forward swept wing divergence or body freedom flutter. For these studies a typical forward swept wing configuration, adversely mass ballasted to create the dynamic characteristics similar to those caused by adding external stores, is investigated. The goal of this study is to establish concept feasibility so that the technology can be considered for future aircraft application during a design as an alternative or option for preventing aeroelastic instabilities. Analyses are conducted to design active systems for the forward swept wing, cantilevered, free in rigid pitch only, and free in rigid pitch and plunge. They are designed such that both aeroelastic instabilities are suppressed simultaneously to a velocity 20 percent above the unaugmented bending torsion flutter speed with gain margins of at least or - 6db at this speed conditions. Obtaining large phase margins is also taken into consideration during the design analyses.