INVESTIGATION OF ELASTIC COUPLING PHENOMENA OF HIGH SPEED RIGID ROTOR SYSTEMS
Rept. for Apr 1962-Jun 1963
LOCKHEED-CALIFORNIA CO BURBANK
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The report describes an investigation of the effects of variations in design parameters on the dynamic characteristics of cantilever blade or rigid rotors. Some fundamental concepts of rigid rotor dynamics including decoupling are presented, as well as a 10-degree-of-freedom rotor stability analysis in hovering and a brief study of the static stability of the model. A dynamic helicopter wind tunnel model having a 10-foot rotor diameter was constructed with three sets of blades and a hub which allowed many variations in geometry and stiffness. Seven rotor configurations were tested. The model and rotors and the testing technique are described, and all the data collected are included. A principal focus of the program was the decoupled, or matched blade, type of rigid rotor. It was demonstrated to simulated air speeds on the order of 240 miles per hour that this type of rotor is stable with extremely small values of control gyro inertia. In addition, it was found that blade matching has a major influence on chordwise oscillating blade loads.