To calculation of frequency parachute system chracteristics

Considered forced oscillations in vertical plane of two most widespread parachute systems (PS) models - a rigid model and a non-rigid parachute and payload model. In the equations of PS the coefficient of the normal aerodynamic force of the canopy is taken as the nonlinear dependence on the angle-of-attack of the canopy. The analysis of forced oscillations is carried out the method of harmonic linearization. The received expressions allow as to compute the frequency characteristics of PS in the frequency range of main and subharmonic resonances (of order 1/2 and 1/3).