The subcritical response and flutter of a slender wing model aircraft

Abstract

An aeroelastic model aircraft of slender planform has been tested in a wind tunnel at low subsonic speeds. The tests comprised measurement of the resonant frequencies and dampings of the first five symmetric modes of deformation with the model mounted on a novel low-stiffness support at mean angles of incidences of +15°, +5°, 0°, -5°, -15°. For zero incidence the speed range was extended to include measurements at speeds up to the critical flutter speed. The results were compared with calculated values based on the five measured still air modes and rigid body motions of the model on its support. Good agreement was obtained for the response in the model deformation modes 1, 2, 3 and 5, and the flutter speed and frequency were predicted accurately. In the mode which became unstable, however, the calculated damping values were somewhat lower than the measured values at subcritical wind speeds.