OPTIMAL-CONTROL OF HELICOPTERS FOLLOWING POWER FAILURE

Helicopter control procedures following power failure were investigate d theoretically by applying optimal control theory. The calculated hei ght-velocity boundaries showed good correlation with flight test resul ts. However, several differences were observed between the optimal sol utions and pilot's control usage, especially in the timing and amplitu de of the collective flare before touchdown. In addition, parameters s uch as pilot reaction delay, collective setting during descent, the lo cation and available field length of the landing site, and wind speed were found to have a significant effect on the success of the emergenc y landing. Some of these effects are not currently taken into account during certification flight tests.