Suppression of bending-torsion flutter in accelerated flight with aero-servo-viscoelastic controls

Craig G. Merrett, Harry H. Hilton, Sahithi Kalidindi, Elliot S. Schwartz

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The Theodorsen function [1] is generalized to non simple harmonic motion and for time dependent flight velocities encountered during maneuvers, changes in altitude, landings, takeoffs, etc. A formulation and examination is undertaken of the dynamic responses of flexible linear viscoelastic lifting surfaces in potential flow and under the influences of unsteady aerodynamic forces, non-simple harmonic motion and time dependent flight velocities. Differential, integral or proportional servo-controllers are added in order to stabilize the system and extend its lifetime. Parametric studies of servo-controllers led to no general conclusions because of the highly complicated phase relations. However, computational simulations indicate that a continual increase in servo control parameters does not necessarily culminate in utter velocity increases, but actually may decrease such thresholds after a maximum control condition has been achieved. The presence of flight maneuvers introduces time de- pendent velocities and coefficients in the governing integro-differential relations. These are solved analytically by piecewise averaging of the coefficients over selected time intervals. Expanded necessary and sufficient utter conditions beyond the customary simple harmonic motion definition are also formulated.

Original languageEnglish (US)
Title of host publicationAIAA Atmospheric Flight Mechanics Conference 2011
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Print)9781624101533
StatePublished - 2011
EventAIAA Atmospheric Flight Mechanics Conference 2011 - Portland, OR, United States
Duration: Aug 8 2011Aug 11 2011

Publication series

NameAIAA Atmospheric Flight Mechanics Conference 2011


ConferenceAIAA Atmospheric Flight Mechanics Conference 2011
Country/TerritoryUnited States
CityPortland, OR

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Fuel Technology
  • Aerospace Engineering
  • Mechanical Engineering


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