Tham khảo tài liệu 'theory design air cushion craft episode 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 186 Stability Fig. The plough-in boundary of . circular motion of water particles 11 knots and speed of tide flow was about 4 knots. It is clear that part of the fault was due to incorrect craft navigation but at least it teaches US a lesson that while it may seem safe to navigate a craft along the beach as a matter of fact it is not safe due to the high surf which could act on the craft to capsize it in heavy weather. Following this accident the UK government set up an investigation which included a major study of hovercraft stability including parametric model tests of several current large craft designs to identify possible improvements particularly to the skirt systems 48 This study produced much useful information and led to the development of the bulbous bow skirt the tapered skirt and revised cushion feed designs. Some of these items have been introduced above the remainder will be described in Chapter 7. Wave length I Fig. The overturning of in very steep beam waves. Trim and water surface deformation under the cushion Introduction Dynamic trim is determined by equilibrium of the steady forces acting on the ACV or SES at speed. The trim will affect drag forces acting on the craft and therefore its ability to accelerate through hump speed to the operational cruising speed. The main purpose of this chapter s investigation is therefore to enable estimation of craft trim at various speeds and identify the optimum values. The starting point for determination of equilibrium is the centre of pressure of the cushion for an ACV and in addition the force vector which results from the hydrodynamic force acting on the hulls of an SES or through the skirt. This may be compared with the forces acting on the hull of a planing boat or catamaran. An important difference from conventional ships regarding determination of the hydrodynamic force and moment is caused by the inner water surface under the pressurized cushion. Conventional ships have
