Evaluation of Limited Authority Attitude Command Architectures for Rotorcraft

Previous work has shown that an attitude-command-attitude-hold with height-hold (ACAH+HH) Response-Type provides significant workload reduction in the degraded visual environment (DVE). That work resulted in a requirement for an ACAH+HH Response-Type in the military rotorcraft flying qualities specification, ADS-33E, for low speed, low altitude flight in degraded visual environments. The supporting data for that requirement is based on tests with full authority flight control systems. The results reported herein indicate that it is possible to achieve most of the workload reduction in the DVE that accrues from a full authority ACAH system, with a limited authority flight control system. Limited authority ACAH was also found to be a significant safety enhancement for brownout encounters.