Effects of Flight Deck Motion in High Seas on the Hovering Maritime Helicopter

Flight test data are examined with a focus on the effects of ship motions on the hovering helicopter. These data include ship motions, pilot collective control input, and helicopter engine torque. Fourier analysis shows collective is closely associated with ship pitch and flight deck vertical acceleration (FDVA), but not with ship roll and flight deck lateral acceleration (FDLA). Correlation between FDVA and collective is very high; correlation between pitch and collective shows similar trends, but at lower levels; and, correlation of collective with roll and FDLA is very low. Correlation between collective and torque is extremely high, and so torque can be directly related to FDVA. Example FDVA and torque data are examined for day and night operations, and for low and high hover. The normal distribution provides the best fits for FDVA; however, the Chi-Square distribution provides better fits for torque in the most severe motion environments.