Motor vehicles – Surface effect vehicles – Having propulsion or control means
Patent
1995-02-23
1996-06-04
Hill, Mitchell J.
Motor vehicles
Surface effect vehicles
Having propulsion or control means
114 67A, 440 37, B60V 111, B60V 114
Patent
active
055224709
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The invention relates to a trimmer for a hovercraft with two engines to provide forward motion, an air compressor to generate the air-cushion beneath the craft and a stabiliser arrangement at its stern.
BACKGROUND ART
Hovercraft are generally fitted with a compressor to generate the necessary air-cushion within a rubber skirt and at least one drive engine for taking straight and/or curve courses. When a curve course is taken, the hovercraft is usually steered by laterally deflecting the jet of air with a lateral rudder, such as is familiar from aircraft construction.
In such hovercraft, the bodywork tilts about the longitudinal axis of stability, the transverse axis of stability or both axes simultaneously, if the centre of gravity shifts due to varying or non-uniform loading with passengers or cargo, for example.
In the worst case, this inclination about one of the axes of stability, caused by a shift in the centre of gravity, can cause the rubber skirt of the hovercraft to dip into the water while travelling. In this case, the rubber skirt would be compressed to a more or less pronounced degree and the buoyancy of the air-cushion reduced in this area. The consequence of this is that the hovercraft dips even further into the water and could even flip over.
Another effect which occurs following a shift in the centre of gravity is thoroughly comparable to the effect of side-winds. This effect arises as a result of the varying gap between the rubber skirt and the ground or the surface of the water and the resultant varying release of the air from the air-cushion. The force component arising in this context pushes the hovercraft in the direction of the shift in the centre of gravity.
In principle, measures to compensate for the shift in the centre of gravity in hovercraft are possible by using additional trimming weights, for example. However, these measures lead to an additional weight load and, thus, to increased energy consumption.
SUMMARY OF THE INVENTION
A steering gear for a hovercraft is described in U.S. Pat. No. 4,249,628 with two fans arranged next to each other at the stern for forward motion. Flaps similar to ailerons are arranged in pivotable fashion about a horizontal axis within an air duct in the air jet downstream of each of the fans which can be moved between a normal position, in which their plane runs parallel to the axis of the air duct, and a fully effective position in which the flaps are positioned transversely, meaning that they almost totally block the air jet. In order to trim the hovercraft about its transverse axis, the aileron-type flaps can be moved upwards or downwards in synchrony. However, this method of trimming is difficult to realise and is only sufficiently effective when taking a straight course.
The underlying task of the invention is therefore to provide a trimmer for a hovercraft, which can be made with simple means and is capable of largely compensating for a shift in the centre of gravity.
The invention relates to a trimmer for a hovercraft with two engines arranged laterally at the stern to generate forward motion, a compressor to generate an air-cushion beneath the craft and a stabilizer arrangement located in the air jet of the engines.
The underlying task of the invention is solved in that the stabilizer arrangement comprises a negatively arranged V-plane whose downwardly directed stabiliser surfaces, which are each fitted with a rudder element, run centrally through the flow outlet apertures of the engines and that an additional force component is generated by additional deflection of the air jets of both engines, which is constantly superimposed on the directional control.
By means of the invention, it is possible to keep the hovercraft in a largely horizontal position by simple means and with a high degree of sensitivity, even in the event of a shift in the centre of gravity. The above-mentioned disadvantages can then no longer occur. The invention particularly improves the safety of the moving craft. Drift, which would
REFERENCES:
patent: 3587771 (1971-06-01), Faure
patent: 4249628 (1981-02-01), Longley
patent: 4421489 (1983-12-01), Van Veldhuizen
patent: 5097919 (1992-03-01), Cox
patent: 5370197 (1994-12-01), Goodwin et al.
Blum Albert
Stiegler Hartmut
Hill Mitchell J.
Syrowik David R.
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