Adaptive Frahm for Variable-Speed Rotor Helicopters

The focus of this paper reports on the technology developed for an adaptive Frahm. The aim was to have a Frahm system adapt its behavior to attenuate vibrations at two specific frequencies representative of 100% rotor rpm and 90% rotor rpm. An approximate quarter scale mass system was designed to test and develop the controlling algorithm. The performance of the Frahm was tuned by moving a mass along a pendulum beam. Higher frequencies moved the mass closer to the pivot point while lower frequencies moved the mass away from the pivot point. Test