Improving the US Army Rotor Smoothing Algorithm and Coefficient Development Process

Aircraft Rotor Smoothing (aka rotor track and balance) is a complicated process that can be very challenging for even the most experienced maintainers. Rotor smoothing is required to reduce a helicopter's 1/revolution vibration levels. This improves crew comfort and reduces crew fatigue. Maintainers make mechanical adjustments to a rotor system that experiences various dynamic and aerodynamic forces. The typical rotor smoothing event involves balance weight adjustments, pitch link adjustments for changes in blade angle of attack, and blade trailing edge tab adjustments that affect a blade's pitching moment and thus its lift. The rotor smoothing equipment used to determine these adjustments incorporate imbedded empirically developed algorithms and coefficients. It is imperative that these algorithms and coefficients are properly developed. Open lines of communication with aircraft manufacturers are essential due to the differences in aircraft and rotor systems design. The differences in aircraft design may require rotor smoothing methods that are unique to its airframe in order to guarantee successful rotor smoothing events.