Evaluation of Methods for Prediction and Prevention of Wing/Store Flutter

Abstract

In response to the need to reduce costs and improve safety for flutter evaluation of aircraft carrying external stores, the Flight Dynamics Laboratory has sponsored several efforts in the technical areas of unsteady aerodynamics, flutter prediction, and active flutter suppression. This paper discusses each of these three areas as they relate to wing/store flutter and presents specific examples from analyses and tests. NLR, the Netherlands, measured aerodynamic data in the wind tunnel at subsonic, transonic, and supersonic speeds on a fighter wing with tip mounted launcher and store and also with underwing pylon and store. Store flutter calculations were performed using both calculated and measured aerodynamics to determine the influence of store aerodynamics on the flutter characteristics.Subscripts qs ref Nomenclature local chord length sectional pitching moment coefficient root chord length sectional normal force coefficient frequency of oscillation freestream Mach number dynamic pressure nondimensional flutter dynamic pressure semispan time nondimensional flutter velocity angle of attack change in a given quantity fraction of semispan amplitude of oscillation fluid mass density angular velocity = 2irf = quasisteady quantity = reference