Algorithm development and software implementation of a multi-point vector method for helicopter rotor balancing

Excessive vibration of the main and tail rotors at the rotation frequency is one of the main causes of reduced airframe service life and degraded crew working conditions. This paper addresses the automation of the balancing stage for a light helicopter. An algorithm is proposed that generalises the classical graphical vector method of trial-weight balancing to an arbitrary number of discrete weight-attachment points with non-uniform angular spacing, which is typical of real rotor-hub designs. From the results of two runs, the developed software tool computes the required corrective weight and its angular position and distributes it between the two nearest actual attachment points by vector decomposition. Two operating modes are implemented – the main rotor (three points) and the tail rotor (four points) – with visualisation of the result and assessment of balancing admissibility. The correctness of the computational core was confirmed by comparison with the established procedure, and the method was validated during actual rotor balancing of four helicopters.