The aerodynamic effects of aspect ratio and sweepback on wing flutter

Abstract

The report describes tests to obtain direct measurements of the aerodynamic effects of aspect ratio and sweepback on wing flutter. The tests were made on rigid wings with root flexibilities. It is shown that measured effects of aspect ratio and sweepback on the flutter of these wings can be represented quite closely in flutter calculations based on two-dimensional flow theory by multiplying the two-dimensional aerodynamic coefficients by appropriate factors. The effect of sweepback is represented by multiplying all aerodynamic coefficients by cos A, where A is the wing leading-edge sweepback, and the effect of aspect ratio is represented by multiplying the aerodynamic damping coefficients by l/ƒ(A) and the stiffness coefficients by 1/[ƒ(A)]² where A is the aspect ratio. For the wings tested an average value for ƒ(A) is ƒ(A) = {1 + (0.8/A)}.