A PRELIMINARY FLIGHT INVESTIGATION OF CROSS-COUPLING AND LATERAL DAMPING FOR NAP-OF-THE EARTH HELICOPTER OPERATIONS

A helicopter in-flight simulation was conducted to look at the effects of variations in roll damping, roll sensitivity, and pitch and roll rate cross-coupling on helicopter flying qualities for NOE operations. The experiment utilized the Ames UH-1H helicopter in-flight simulator, which is equipped with the V/STOLAND avionics system. The response envelope of this vehicle allowed for the simulation of configurations in the low-to-moderate damping and sensitivity range. A visual, low-level slalom course was set up, using the 1000-ft markers of an 8000-ft runway to evaluate the various configurations. Test results are shown in terms of Cooper-Harper pilot ratings. These results show good consistency with previous ground simulator results and with some elements of flying qualities criteria, such as those of MIL-F-83300 and MIL-H-8501A.