Some flutter tests on swept-back wings using ground-launched rockets

Abstract

This report gives the results of tests on flutter models of untapered wings with 20 deg, 40 deg and 60 deg sweepback. Tests have been made up to a Mach number of 1.4. A comparison is made between the measured flutter speeds and the speeds estimated using a flutter speed formula. Modifications to the formula are proposed which include a compressibility correction of the form (1.0 - 0.166M cos A), 0 < M cos A < 1.6, where A is the angle of sweepback. A comparison is also made between measured flutter speeds and those calculated using two-dimensional incompressible flow theory. This shows that the calculated speeds are lower than the measured speeds except in the transonic region, where they are in some cases slightly higher. The calculated flutter frequencies are on the average some 20 per cent higher than the measured values.