Design of Higher Harmonic Control for the Abc

This paper presents the results of a design study showing the potential for successful application of higher harmonic control on the full scale hingeless coaxial ABC rotor helicopter. The results indicate that a 90% reduction in vibration from untreated levels is achievable with higher harmonic control inputs of the order of 0.5° to 2°. Effects on blade loads, control loads and aircraft systems are shown to be reasonable. A control scheme for the system is identified and a hardware feasibility study accomplished.