Abstract: An iterative computation method for nonlinear forced vibration equation on helicop- ter blade aerodynamic load is given. Initial load of blade is calculated by supposing that downwash flow is determined, and then flapping-swing-torsional elastic defonnation is calcu- lated by nonlinear foreed vibration equation. Harmonic load and elastic defonnation of various orders in blades are calculated in the x-type helicopter computation example;the calculated results coincide with the test data.

Key words: rotary wings, vibration effects, loads (forces), iterative solution