Abstract
Helicopter rotor instability coupled with its support structure in forward flight is investigated. The linearized equations of hub and blade motions around the rotor periodic trim conditions are obtained, and the system instability is evaluated based on the Floquet theorem. By taking account of blade pitch angle variations due to hub motions, simulation results show that instability similar to the SH-60K case occurs at high speed condition, and predicted stability boundaries show the fair agreement with the SH-60K flight test results.
