LOW FREQUENCY INSTABILITIES OF FREE SYSTEMS

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.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1963
Accession Number
AD0426543

Entities

People

  • Jack H. Hill
  • Robert G. Schwendler

Tags

Communities of Interest

  • Air Platforms
  • Weapons Technologies

DTIC Thesaurus Topics

  • Aerodynamic Configurations
  • Aerodynamic Forces
  • Aircrafts
  • Airframes
  • Altitude
  • Analog Computers
  • Computers
  • Dynamic Pressure
  • Dynamic Response
  • Equations Of Motion
  • Frequency
  • Fuselages
  • Measurement
  • Resonant Frequency
  • Spars
  • Steady State
  • Vehicles

Fields of Study

  • Physics

Readers

  • Control Systems Engineering.