ENVELOPE FUNCTION - A TOOL FOR ANALYZING FLUTTER DATA

In this article a new tool for flutter clearance is presented and a pr eliminary assessment of its capabilities undertaken. It is intended to be complementary to other approaches. The method is based on quantify ing the change in the shape of the decay envelope associated with cont rol pulse responses or impulse response functions. An indication of ov erall stability is obtained without curve fitting by way of a shape pa rameter which quickly shows whether there has been any significant cha nge since the last test point. In addition, the envelope functions can be overlayed from different speeds. The method is illustrated with da ta from a simulated aeroelastic model of a multiengined transport airc raft, and the effects of turbulence are considered. Finally, the metho d is successfully applied to real flight test data.