Flutter Analysis of an F-16A/B in Heavy Store Configuration

Abstract

This work compares Several analytical approaches are compared for in-flight flutter margin calculations for an F-16A/B in heavy store configuration. Nominal flutter model formulations are developed in terms of the dynamic pressure and the Macb number. These analysis models are expressed within the linear fractional transformation (LFT) framework for the determination of flutter onset conditions using the structured singular value μ analysis. The results obtained from classical analysis tools such as the P and P-K method, as well as the μ method are compared with each other and validated using actual flight-test data. The LFT model parameterization in terms of match-point Mach number is novel and permits a natural and efficient flight-test procedure for flutter envelope clearance. Structural parameter variations such as changes in wing mass, as well uncertainties in damping and/or stiffness, are also incorporated in the LFT formulation and permit the calculation of robust match-point flutter margins. The μ-analysis results obtained from such model formulations incorporating several simultaneous parameter variations reveal and explain the complex physical mechanisms that have led to limit-cycle oscillation conditions encountered during the flight tests.