Flutter Monitoring by Means of the Modal Envelope Function

Abstract

This paper presents flight flutter data evaluation methods used during the flight flutter tests of the high-altitude aircraft STRATO~2C. An oscillating mass excitation and control surface raps were applied during the tests. The paper focuses on the pulse excitation. The resulting free decay measurements were analyzed by means of a modified Ibrahim Time Domain method and the modal envelope function, a tool for quick damping estimation. The data evaluation methods are briefly explained, the flight flutter tests on the aircraft are elucidated, and test results derived from the different analysis methods are compared. The advantages and drawbacks of each method are pointed out.