An experimental and analytical investigation of stall effects on flap-lag stability in forward flightExperiments have been performed with a 1.62 m diameter hingeless rotor in a wind tunnel to investigate flap-lag stability of isolated rotors in forward flight. The three-bladed rotor model closely approaches the simple theoretical concept of a hingeless rotor as a set of rigid, articulated flap-lag blades with offset and spring restrained flap and lag hinges. Lag regressing mode stability data was obtained for advance ratios as high as 0.55 for various combinations of collective pitch and shaft angle. The prediction includes quasi-steady stall effects on rotor trim and Floquet stability analyses. Correlation between data and prediction is presented and is compared with that of an earlier study based on a linear theory without stall effects. While the results with stall effects show marked differences from the linear theory results, the stall theory still falls short of adequate agreement with the experimental data.
Document ID
19890035934
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Nagabhushanam, J. (Indian Institute of Science Bangalore, India)
Gaonkar, Gopal H. (Florida Atlantic University Boca Raton, United States)
Mcnulty, Michael J. (U.S. Army, Aeroflightdynamics Directorate, Moffett Field CA, United States)