Flight Evaluation of Elastomeric Bearings in an AH-1 Helicopter Main Rotor
BELL HELICOPTER TEXTRON INC FORT WORTH TX
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Presented in this report are the results of a flight test program conducted to evaluate elastomeric bearings in the main rotor of an AH-1G helicopter. An experimental main rotor was fabricated and tested using only elastomeric bearings in both the flapping and pitch change axes. With this rotor, the flapping bearings carry the rotor drive and lift loads and allow the flapping motions. Two pitch change bearings were used in each grip to carry the blade bending and shear loads and transfer the blade centrifugal force to the rotor yoke. These bearings also accommodate the blade collective and cyclic pitch change motions. Torsional, radial, and axial load deflection curves are given for the flapping and pitch change bearings. In addition, the results from a limited endurance test program are included for the pitch change bearing. The purpose of the endurance tests was to assure that bearing metal parts would not fail prior to elastomer shredding. Thus, visual inspection of the elastomeric bearings was considered sufficient for safety-of-flight during the test program. The test results have shown the feasibility of elastomeric bearings for helicopter main rotor applications.
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