Cushioning characteristic and parameter design of a soft landing airbag

A normal soft landing process with a gas-filled bag can be decomposed into two physical stages; the first one is an adiabatic compression of airbag, then the second one is a release of landing shock energy. Based on thermal dynamic and rigid dynamic equations, the analytical model of a soft landing airbag was developed, thus a simple and quick numerical solving method for cushioning response was presented. As an example, the parameter determination method for a vertical cylinder soft landing airbag of an unmanned aircraft was proposed, and the parameters included the height of the airbag, the bottom area of the airbag and the area of the vent orifices. The cushioning time histories of the soft landing air-bags with different types of vent orifices including no gas bleed, constant-area orifices and controllable orifices were calculated by a Matlab program. Compraring these simulation results, the advantages and disadvantages of different soft landing airbags were concluded, and some improvement advice on design of a soft landing airbag was proposed.