VIBRATION REDUCTION IN ROTORCRAFT USING ACTIVE CONTROL - A COMPARISONOF VARIOUS APPROACHES

This paper presents a concise review of the state of the art for vibra tion reduction in rotorcraft using active controls, The principal appr oaches to vibration reduction in helicopters described in the paper ar e 1) higher harmonic control, 2) individual blade control, 3) vibratio n reduction using an actively controlled flap located on the blade, an d 4) active control of structural response, The special attributes of the coupled rotor/flexible fuselage vibration reduction problem are al so briefly discussed to emphasize that vibration reduction at the hub is not equivalent to acceleration reduction at specific fuselage locat ions, Based on the comparison of the various approaches, it appears th at the actively controlled flap has remarkable potential for vibration reduction.