Evaluation of classical flutter analysis for the prediction of limit cycle oscillations

Abstract

Classical linear flutter analyses are correlated to the flight test results of a fighter-type aircraft which exhibits nonlinear flutter characteristics. Four critical types of observed flutter behavior are described. Two types, the classical flutter response and one type of typical limit cycle oscillation (LCO) response, are noted to consistently occur in a clearly defined regime in the flight test envelope. The regimes for the other typical LCO type and the non-typical LCO responses are not as clearly defined. The flutter analysis results show consistent trends which could be used to indicate the occurrence of these critical response characteristics. In this fashion, classical linear flutter analysis techniques could be used to predict nonlinear LCO. These findings can substantially reduce the number of flutter flight test missions required for weapon system certification.