ROTOR AIR LOADS, BLADE MOTION, AND STRESS CAUSED BY TRANSIENT INPUTS OF SHAFT TORQUE AS RELATED TO STOPPABLE ROTOR OPERATION

The transient-response calculation method is extended to yield aerodynamic loadings and elastic-blade motions in response to changes of shaft torque input. Loadings, bending moments, and modal responses are obtained for a teetering rotor experiencing both a 100- and a 50-percent power loss. Similarly, responses are computed for a hingeless rotor experiencing a 100- percent power loss and for a hingeless rotor being braked from an initial operational condition corresponding to 100-percent rpm and a nominal value of zero lift. This hingeless rotor is also started up from a stopped position. Examination of the results obtained in these computations indicates that 1 reasonable aerodynamic loadings can be predicted irrespective of the radial to tangetial velocity ratio and 2 no loading or structural response phenomena result in the examined flight condition which would indicate that power loss, braking, and rotor stopping have serious consequences with respect to the creation of unusual blade-wake interaction phenomena.