A Time-Domain Method for Establishing Modal Parameters and Flutter Margins From Space Shuttle Flight Data

Accelerometer data from Space Shuttle flights are used to identify the modal components of decaying response. This is done using a modified version of the Ibrahim time domain (ITD) method. Identified modal response coherences and the data from which they are extracted are maximized by manipulating sample sizes and start times and by filtering. This leads to a more consistent set of damping rates and thus provides greater confidence in projected flutter margins. Applying this procedure to response data that are less noisy than flight test data should produce satisfactory results with less filtering.