LOW FREQUENCY INSTABILITIES OF FREE SYSTEMS
- 1 November 1963
- report
- Published by Defense Technical Information Center (DTIC)
Abstract
Mode interaction instabilities of aircraft were investigated. Mode interaction refers to coupling between an elastic mode and a rigid body mode of the free system. Three rather general airframe configurations are analyzed in detail. It is shown that systems which tend toward steady state divergence are particularly susceptible to mode interaction. Also, that aerodynamic damping terms can have a destabilizing effect upon a free system. The analyses show that aeroelastic systems which possess no finite frequency elastic mode can be susceptible to a finite frequency in stability. Computer studies of several different airframe configurations are discussed. An appen dix contains stability charts for an aircraft having two rigid body modes and one elastic mode.Keywords
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