UNCLASSIFIED/UNLIMITED Aeroelastic Limit Cycle Oscillations in High Performance Aircraft Earl Hugh Dowell Duke University Durham, North Carolina United States dowell@mail.ee.duke.edu ABSTRACT Aeroelastic Limit Cycle Oscillations in High Performance Aircraft An overview is presented of limit cycle oscillations (LCO) that occur due to the nonlinear aeroelastic response of high performance aircraft. Both theoretical/computational and experimental work including wind tunnel and flight test data are discussed. Primary emphasis is on (1) computational/experimental correlation and (2) recent developments in constructing rapid solution methods for computational models that retain state of the art high fidelity accuracy. Results for a High Altitude Long Endurance (HALE) configuration, a fighter aircraft and a morphing (folding) wing illustrate the state of the art and also demonstrate the sensitivity of flutter and LCO prediction that may occur due to modest changes in key system parameters. 1.0 ACKNOWLEDGEMENTS The author would like to acknowledge the members of the Duke team who have contributed to his education on this topic over the years including Peter Attar, Elizabeth Bloomhardt, Howard Conyers, Chad Custer, Kenneth Hall, Justin Jaworski, Robert Kielb, Tomokazu Miyakozawa, Meredith Spiker, Deman Tang and Jeffrey Thomas. He would also like to acknowledge his longtime mentor from whom he first learned about aeroelasticity and continues to learn so much, John Dugundji of MIT, and his current collaborators from other organizations including Charles Denegri Jr. of the SEEK EAGLE Office, Philip Beran and Victor Giurgiutiu of the AFRL and Moti Karpel and Daniella Raveh of the Technion. And indeed to the attendees of this symposium and our many colleagues in the aeroelastic community appreciation is given. 1.1 INTRODUCTION In this paper the fundamental physical phenomena associated with limit cycle oscillations (LCO) of aeroelastic systems are discussed. There have been a number of excellent reviews of the relevant literature [1- 13] and the reader is referred to those for a more comprehensive account of the subject. Among the subjects that have been considered by aeroelasticians and aerospace engineers are (1) flutter and LCO of fighter aircraft with various wing store combinations, (2) wing rock and abrupt wing stall (AWS) of fighter aircraft at high angles of attack, (3) flutter and LCO of High Altitude Long Endurance (HALE) configurations and (4) RTO-MP-AVT-152 KN1 - 1 UNCLASSIFIED/UNLIMITED