Shape-form of Air Cushion Vehicle’s Flexible Skirt under Partial-cushion Blown State

Abstract Sometimes, Air Cushion Vehicle (ACV) needs to operate in the off-cushion (afloat) state with lowly rotating lift fans. In above case, the flexible skirt is at bubble state, which is partially blown into inflating shape to reduce resistanc and water draft. Research on bubble skirt shape-form is still a blank. Through observation of full-scale ACV’s bubble skirt shape-form, based on structure of typical skirt sect, an analytical method was firstly presented to calculate the bubble skirt shape-form of the afloat ACV under the partially inflated state. A program was developed in MATLAB based on this analytical method, and its results agree well with those obtained by FEM method in Abaqus, also with phenomenon of the afloat full-scale ship’s skirt shape in the bubble state. Based on the branch and boundary cutting method, program for bubble skirt shape-form using Visual LISP in AutoCAD. Compared with the FEM method in Abaqus, the presented analytical method can significantly reduce the time required for 3D modeling, FEM analysis, and calculations. On the other hand, the analytical program developed in Visual LISP can be translate into VBA to be embedded into the CATIA framework for ACV intact/damaged stability analysis with the bubble skirt. The program can deal with alomots all typical skirt sect, such as bag-finer type, double-lobe-finger type, bag-cone tupe, double-bag-cone type.