The Use of Limited Authority Response Types to Improve Helicopter Handling Qualities during Flight in Degraded Visual Environments

The concept and rationale behind developing a Limited Authority Response 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 authority attitude response type. Selected results from a piloted handling qualities experiment, conducted on the NRC Bell 205 Airborne Simulator, addressing this concept are presented. This experiment examined the handling qualities of a “UH-60 - like” helicopter with various LART systems while conducting operations in poor night vision goggle conditions. The results indicate an improvement in handling qualities for systems with attitude authority as low as 2.5 degrees and a general dislike of systems using parallel servos to increase the overall attitude authority. Provision of a pilot selectable height hold system during flight in DVE provided the greatest handling qualities improvement. Pilot comments and some inconsistent results suggest more detailed research is required to confirm the results prior to practical applications of the concept.