Motor vehicles – Surface effect vehicles – Having propulsion or control means
Patent
1994-12-16
1996-05-28
Hurley, Kevin T.
Motor vehicles
Surface effect vehicles
Having propulsion or control means
B60V 111
Patent
active
055202608
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a steering device for a hovercraft having at least one engine to drive it and a compressor to provide an air-cushion which can be generated below the craft, and in which there is a rudder device at the stern to control the direction of travel.
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 emerging from the engine. Lateral rudders familiar from aircraft construction and arranged directly in the jet of air are generally used for this lateral deflection of the jet of air. An alternative possibility for controlling the direction of travel of the hovercraft is to laterally deflect the jet of air by swivelling the exhaust diffusor or the entire engine.
In this context, however, a more or less pronounced lateral drift in the direction of the outside of the curve occurs as a function of the speed travelled, with the result that steering becomes difficult during such manoeuvres on account of the large radii of curvature required. Furthermore, when taking a curve course, the hovercraft tilts about the transverse axis of stability in the direction of the outside of the curve due to the centrifugal force acting on the centre of gravity. Thus, a larger air gap forms between the rubber skirt and the ground or the surface of the water on the inside of the curve, with the result that additional air is expelled on this side. An additional force component is produced in this manner, on top of the centrifugal force, which causes an increase in the drift. The result is an increase in the necessary radii of curvature in all speed ranges.
The effect of the hovercraft tilting about the transverse axis of stability in the direction of the outside of the curve arises regardless of the manner in which the craft is steered in the curve course.
A similar effect is also produced by side-winds, which cause the hovercraft to tilt leewards about the transverse axis, this resulting in increased drift.
The aim of the invention is therefore to provide a steering device for a hovercraft providing a substantial improvement in taking a curve course and a considerable reduction in the radii of curvature in all speed ranges.
The invention relates to a steering device for a hovercraft having at least one engine to drive it and an engine to provide an air-cushion which can be generated below the craft, and in which there is a rudder device at the stern to control the direction of travel.
The underlying task of the invention is solved by providing the engines with a jet deflection device, with which the jet of air emerging from the engines can be deflected when a curve course is taken, in such a way as to produce a force component about the transverse axis of stability which counteracts the centrifugal force.
As a result of producing a force component which acts above the centre of gravity and counteracts the centrifugal force when taking a curve course, the hovercraft tilts towards the inside of the curve taken.
This inclination towards the inside of the curve causes a reduction in size of the air gap between the bottom edge of the rubber skirt and the ground or the surface of the water on this side, and an increase on the outside of the curve. An additional force component is thus produced in the direction of the inside of the curve, which reduces the drift of the hovercraft and, at the same time, markedly improves manoeuvrability at slow speeds. The reduction in drift simultaneously reduces the radii of curvature which can be achieved.
In an improved version of the invention, two engines are arranged next to each other at the stern of the hovercraft, each engine being provided with a downstream jet deflection device. This arrangement leads to markedly better control of the inclination of the hovercraft when taking a curve course.
The air jet is then deflected in such a way that the air
REFERENCES:
patent: 3262510 (1966-07-01), Froehler
patent: 4151893 (1979-05-01), Mantle
patent: 4249628 (1981-02-01), Longley
patent: 5096012 (1992-03-01), Chia et al.
Blum Albert
Stiegler Hartmut
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