The flutter analysis of the JS1 glider

Abstract

A flutter analysis of the new prototype 18-meter glass glider, the JS1 Revelation, was performed. The analysis was conducted in two main parts, a modal analysis done by a ground vibration test, followed by a flutter prediction. A ground vibration test was performed on the glider in two configurations: with no water ballast and with water ballast in the wings. For each of these cases the 1st, 2nd and 3rd symmetric and anti-symmetric wing bending modes and wing torsion modes were extracted as well as fin, stabilizer and fuselage modes. All of these modes were extracted in the frequency range 1 Hz - 32 Hz. The natural frequency, modal damping and mode shape of each mode are among the modal results. The flutter prediction was done with the software code SAF (Subsonic Aerodynamic Flutter). SAF makes use of a panel model of the glider and utilized the doublet lattice method and p-k flutter solution method. So far, results in the form of damping vs. velocity and frequency vs. velocity graphs indicated stability of main surface modes in the velocity range up to 1.2VD up to an altitude of 8000 meters.