THE USE OF LIMITED AUTHORITY RESPONSE TYPES TO IMPROVE HELICOPTER HANDLING QUALITIES DURING FLIGHT IN DEGRADED VISUAL ENVIRONMENTS

The concept and rationale involved in developing a Limited Authority R esponse Type (LART) to improve handling qualities of a helicopter for operations in degraded visual environments (DVE) is explained. A LART may be achieved by reprogramming existing, limited authority stability augmentation system actuators to produce a moderate bandwidth, low au thority attitude response. A summary of the results from a piloted han dling qualities experiment, conducted on the NRC Bell 205 Airborne Sim ulator, addressing this concept are presented. This experiment examine d the handling qualities of a ''UH-60-like'' helicopter with various L ART systems while conducting operations in degraded night vision goggl e conditions. The results indicate an improvement in handling qualitie s for systems with attitude authority as low as 25 degrees and a gener al dislike of systems using parallel servos to increase the overall at titude authority. Provision of a pilot selectable height hold system d uring flight in DVE provided the greatest handling qualities improveme nt. Some inconsistancy in pilot ratings and comments suggest more deta iled research is required to confirm the results prior to practical ap plications of the concept.