Simulation of Natural Oscillations of the Air Assault Rappelling System “Kanat-1”

Abstract

The main purpose of the article is to consider the simulation of the natural oscillations of the air assault rappelling system “Kanat-1”.
 The object of consideration is a set of removable onboard equipment for rappelling air assault "Kanat-1" for landing from the cargo hatch of Mi-8 helicopters.
 Air assault rappelling system is an oscillating system that has certain natural frequencies of oscillation of the item, which depend on the number of paratroopers on the rope and their placement on it. The airframe of the Mi-8 helicopter has its own frequencies within the ranges of 3.1 - 3.3; 8 - 9; 15 - 17 Hz with which, and their divisibles the natural frequencies of the item should not coincide. In real operating conditions, determining the natural frequencies of the elements of the item under load is problematic.
 A system of dynamic models is built which allows determining the natural frequencies of air assault rappelling system oscillations at arbitrary placement of up to three paratroopers weighing up to 140 kg each, which can be hung simultaneously on one of the ropes in constant motion while moving the points of contact with the rope. In general, at the maximum load on the rope (three paratroopers), the mathematical model represents a system of three second-order differential equations. Eight variants for loading the rope with paratroopers are considered. The obtained oscillation frequencies of the air assault rappelling system do not coincide with the oscillation frequencies of the helicopter airframe which proves the effectivity of the air assault rappelling system.
 Recommendations for regulation of frequency characteristics of air assault rappelling system by replacement of a fastening element of a rope to a traverse are developed.