US3587771A - Ground-effect machines propelled by air or gas streams - Google Patents

Abstract

IN A GROUND EFFECT MACHINE HAVING A CENTRAL LIFT CHAMBER FOR ONE OR MORE PRESSURE-FLUID CUSHIONS, SUPPLIED WITH PRESSURE FLUID BY PRESSURE-FLUID GENERATOR, AND ONE OR MORE FURTHER PRESSURE-FLUID GENERATORS EACH HAVING A DELIVERY DUCT HAVING AN ADJUSTABLE CROSS SECTION EJECTION NOZZLE FOR DRIVING THE MACHINE, THE IMPROVEMENT COMPRISING ONE OR MORE ORI-

FICES CONNECTING THE LIFT CHAMBER WITH THE DELIVERY DUCT OR DUCTS, AND/OR INTERCONNECTING THE DELIVERY DUCTS, FOR MAINTAINING THE LIFT AND DRIVE OF THE MACHINE IN THE EVENT OF FAILURE OF ALL PRESSURE-FLUID GENERATORS BUT ONE.

Description

United States Patent [72] lnventor Marc Henri Jean Faure Saint-Maur des Fosses, France [2!] Appl. No. 841,291 [22] Filed July 14, 1969 [4S] Patented June 28, 1971 [73] Assignee Soclete DEtndes Et De Developpement Des Aeroglisseurs Marius Terrestres Et Amphlbles S.E.D.A.M. Paris, France [32] Priority July 23, 1968 [33] France [31 1 160,274

[54] GROUND-EFFECT MACHINES PROPELLED BY AIR 0R GAS STREAMS 9 Claims, 2 Drawing Figs.

{52] U.S.CI. 180/120, 1 80/ l 17 [51] Int. Cl. B60v 1/14 150 Field of Search ,I 180/120, 1 17, 129

[561 References Cited UNITED. STATES PATENTS 3,463,263

8/1969 Winter Primary Examiner-A. Harry Levy Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: In a ground effect machine having a central lift GROUND-EFFECT MACHINES PROPELLED BY AIR OR GAS STREAMS The invention relates to ground effect machines borne by pressure gas and driven and possibly controlled and braked by one or more streams of pressure gas. Machines of this kind are usually borne by a single fluid cushion or by a number of cushions separated from one another by partitions and communicating with a central lift chamber, the single cushion of the central chamber being supplied by one or more lift generators, as a rule in the form of an axial flow fan or compressor whose axis is substantially vertical. The or each stream is supplied with pressure gas by one or more propelling (drive) generators which usually take the form of axial flow fans or air compressors having a substantially horizontal axis.

According to this invention, the delivery duct of a drive generator has an adjustable nozzle at its end and communicates by one or more lateral orifices with the single cushion or the lift chamber and/or with the delivery duct of another drive generator also having an adjustable nozzle at its end.

The ejection cross section of the or each nozzle can be controlled either directly by the pilot or driver of the machine or automatically, so that the static pressure in the or each delivery duct remains constant at a selected value near the or each orifice. According to the invention, under automatic control the ejection cross section of the or each nozzle is so adjusted that the total pressure at the nozzle exit or exits remains constant at a selected value, eg a valve set up by the pilot. In this even, the or each intercommunicating orifice is preferably disposed in a zone of the or each delivery duct where the static pressure represents a considerable proportion, e.g. approximately at least 30 percent of the total pressure.

If there are intercommunicating orifices between the discharge ducts of two or more drive gas generators, the static pressures are therefore equal on both sides of such orifices. If there are interconnecting orifices between the cushion (or lift chamber) and one or more delivery ducts, it is possible to maintain either equal static pressures on either sides of the orifices, by appropriate choice of the static pressure, or, in the embodiment mentioned in the foregoing, the total pressure in the or each delivery duct.

Consequently, when the generators operate normally, the static pressures on each side of the or each orifice are equal and so the orifices have no effect. If one or more generators stops, e.g. because of adefect, the or each gas circuit normally supplied by the or each stopped generator is supplied via the or each orifice by the or each generator still in operation, the or each nozzle being automatically adjusted or adjusted by the pilot to balance out deliveries in the various intercommunicating gas circuits.

The invention therefore has the advantage of great mechanical simplicity. Since each pressure gas or air generator is driven by a motor and the motors are not interconnected mechanically, in the event of one or more motors failing, and providing that one of then still continues to operate, the stream-based lift and drive and, where applicable, the streambased braking and control continue to operate. The drive and lift system operates with maximum efficiency in normal conditions since each generator is tailored to suit its particular operation. In the event of one or more motors failing, efficiency drops, but the system still goes on operating without the need for any control operation since the circuits of or each failed generator are supplied with gas or air through the interconnecting orifices by the or each generator which remains in operation.

The invention is also of use, when the machine is travelling over uneven ground or sea waves, in helping to reduce overpressure in the or each cushion, and the resulting vertical acceleration.

The following description, taken together with the accompanying exemplary nonlimitative drawings, will show clearly the various features of the invention and how they may be carried into effect, any feature which is disclosed by the drawings and text forming of course part of the invention.

In the drawings:

FIG. 1 is a plan view, with a partial section on the line H of FIG. 2, of a ground effect machine comprising the system according to the invention.

FIG. 2 is a view in elevation, with a partial section on the line lI-II of FIG. 1.

The ground effect vehicle shown in the drawings is of use more particularly for travel over the sea and has a bottom lift chamber 1 forming an air cushion and supplied by a substantially vertical-axis fan 2 shown in diagrammatic form and driven by a motor 20. Diagrammatically shown substantially horizontal-axis and parallel fans 3, 4 driven by motors 3a, 4a respectively deliver air to ducts 5, 6. Each such duct has at its rearward end an adjustable nozzle 7, 8i.e. a nozzle having at least one moving wall diagrammatically shown as a flap 9, l0 pivoted around a place 9a, 10a. The airstreams issuing from the nozzles 7, 8 serve to drive the machine.

Control at high speeds of travel can be by conventional means, such as moving fins (not shown). Control at low speeds of travel and inbraking is by jet reversal facilities comprising in each delivery duct 5, 6, a number of deflecting blade systems 11, 12 and flaps 13, 14 pivoted at places 13a, respectively. In normal forwards travel the two flaps l3, 14 are in the solid-line position in which they cover the blade systems ll, 12; the nozzles therefore eject rearwardly directed streams 15, 16 which drive the machine forwards. lf flap 14 is pivoted into the chain-line position 14b, the air delivered by the fan 4 is deflected by the blade systems 12 to form a forwardly directed stream 1611 which cooperates with the stream 15 to turn the machine to the left about itself. Simultaneous and differential operations of the flaps 13, 14 can provide all combinations of forwards and reverse travel, braking and turning to both hands.

According to the invention, the delivery ducts 5, 6 intercommunicate with one another via an orifice 17 in their common wall 18, and each such duct communicates with the lift chamber 1 via an orifice 19,20 respectively in the bottom wall 21 providing a separation from chamber 1.

Each nozzle 7, 8 can be controlled either by the pilot of the machine or by an automatic device adapted to maintain at a constant preset value the total pressure P, of the airflow at the nozzle exit. Such control facilities are diagrammatically shown. The control facility for the nozzle 7 comprises a sensor 22, eg a Venturi tube, detecting total pressure P at the nozzle exit, and a servomotor 23 which operates the flap 9 to keep the total pressure at a pilot-set value; similarly, the facility for controlling the nozzle 8 acts on the flap 10 in response to the total pressure variations detected by a like Venturi tube at the exit of the nozzle 8. Control facilities of this kind are familiar and are easier to devise in proportion as the response time is longera few tenths ofa second in this particular case.

Preferably, the orifice l7 interconnecting the ducts 5, 6 is pierced in a zone of the wall 18 where the static pressure P in each duct is at least 30 percent of the total pressure P Since in normal operation the total pressures at the exits of the nozzles 7, 8 are kept at the value set up by the pilot, the static pressures are therefore substantially equal in the two ducts near the orifice 17, and the airflows through the two ducts are substantially independent of one another.

In the embodiment shown, the orifices 19, 20 are pierced substantially in the same zone of the ducts 5, 6 as is the orifice 17. The shape of the ducts 5, 6 must be such that in normal operation-i.e., when the machine is travelling forwards with its three fans operating-the static pressure P of the drive airflows in each duct near the orifices 19, 20 is equal to the cushion pressure P in the lift chamber 1; skilled addressees can determine the pattern which the drive airflow cross section must follow along the ducts to achieve this result for a given load on the machine, e.g. the average load.

Variations in the loading of the machine cause variations of air-cushion pressure P and the pilot must of course so alter the set total-pressure value P for the nozzles 7, 8 that the static pressure P,- in the ducts 5, 6 near the orifices 19, 20 remains equal to the pressure P,- in chamber 1. In practice, the

pressure variations therein may reach a maximum of 2:] (the ratio of the fully loaded weight of the machine to its tare weight). As a simple calculation will show, using conventional kinds of fan for the fans 3, 4, if the static pressure P near the orifices 19, 20 is approximately 30 percent of the total pressure P in the ducts 5, 6, as has been seen in the foregoing, it :20 percent variation of the exit cross section of the nozzles 7, 8 will provide a total static pressure variation in the ratio 2:1. The pilot can therefore act on the nozzles either directly or by altering the set total-pressure value to balance the pressure on either side of the orifices 19, 20, whatever the machine loading may be.

Clearly, therefore, when the three fans 2-4 are operating normally the orifices l7, 19, 20 have no effect and the operation proceeds as if such orifices were closed.

If the lift fan 2 fails, the static-pressure equilibrium near the orifices 19, 20 is disturbed and some of the drive airflows pass to supply the lift chamber 1 through the orifices 19, 20. The total pressure near the nozzles 7, 8 therefore drops and the automatic control facility acts on the flaps 9, to reduce the cross section of the nozzles so as to maintain the total pressure at the set value. Of course, the flow cross section of the orifices 19, must be large enough for the air flow through them to be able to maintain in chamber 1 a static pressure substantially equal to the static pressure near the orifices in the ducts 5, 6. V

Conversely, if the two drive fans 3, 4 fail, some of the lift air goes from chamber 1 into ducts 5, 6 through orifices 19, 20 at a rate of flow determined by the flow cross section of the orifices 19, 20 and by the cross section of the nozzles 7, 8, which the control facility decreases to keep the total pressure of the drive air at the set value.

If any single one of the drive fans fails, e.g. the fan 3, the drive rates of flow balance one another via the orifice 17 with a reduction in the cross section of the nozzles 7, 8. The airflow through the orifices 19, 20 is zero or very reduced.

If the lift fan 2 fails simultaneously with any drive fan, e.g. the drive fan 3, some of the delivery from fan 4 enters duct through orifice 17 and another proportion of such air enters chamber 1 through orifice 20. The nozzles 7, 8 are open only very slightly, but stream-based lift, drive, braking and control are ensured.

If one or more fans fails, air may be delivered through the inlet orifices of the failed fans, but pressure losses on reverse operation are usually so high that a'negligible amount of air is delivered in this way. However, automatic or controlled flaps can be provided too, e.g. in extension of the fan-deflecting blades.

In the event of accidental overpressure in lift chamber 1 due e.g. to the machine passing over a bump or a wave and lasting, as a rule, just for a few hundredths ofa second, some of the lift air goes from chamber 1 through orifices 19,20 into the drive ducts 5, 6 before the automatic control facility for the nozzles 7, 8 has time to respond. This feature reduces overpressure peaks and the resulting vertical accelerations.

Iclaim:

l. A machine comprising at least one pressure-fluid generator adapted to deliver fluid pressure to a confinement device bounding at least one pressure-fluid cushion for lifting the machine, at least two pressure-fluid generators each having a delivery duct having an adjustable cross section nozzle adapted to eject a fluid stream to propel the machine, an ori fice extending from the confinement device into at least one delivery duct, and at least one intercommunicating orifice between the delivery ducts.

2. A machine as set forth in claim 1 wherein the orifice extending from the confinement device to at least one delivery duct, and the said intercommunicating orifice, are disposed in a region where the static fluid pressure in each delivery duct is approximately 30 percent of the total fluid pressure in such delivery ducts.

3. A surface effect machine of the kind having a cushion system which comprises a cushion space and cushion generator means for delivering pressure flUlCl to said space to maintain cushion pressure therein, and a propulsion system which comprises a discharge duct and jet generator means for delivering motive fluid to said duct to maintain motive flow therethrough, wherein the improvement comprises:

a variable area-propelling nozzle connected endwise with said discharge duct to be fed with said motive flow,

means for regulating the area of said propelling nozzle, said regulating means being sensitive to variations in total pressure of said motive flow in said discharge duct and thereby regulating said area in response to such vibrations whereby said total pressure is maintained at a substantially constant preset value, and

substantially unobstructed fluid shunting means permanently interconnecting an intermediate portion of said discharge duct and said cushion space for equalizing static pressures obtaining respectively in said cushion space and in said discharge duct.

4. Machine as claimed in claim 3, wherein said intermediate duct portion is selected such that said static pressure thereat amounts to substantially 30 percent ofsaid total pressure.

5. A machine as claimed in claim 3, wherein said nozzleregulating means comprise total pressure sensing means positioned in said motive flow, and nozzle area varying means under the control of said sensing means.

6. A machine as claimed in claim 3, further comprising a further discharge duct, furtherjet generator means for delivering motive fluid to said further duct to maintain further motive flow therethrough, a further variable area propelling nozzle connected endwise with said further discharge duct to be fed with said further motive flow, and further nozzle-regulating means for controlling the area of said further propelling nozzle in response to variations in total pressure of said further motive flow whereby said total pressure is maintained at said substantially constant preset value.

7. A machine as claimed in claim 6, further comprising a further substantially unobstructed fluid shunting means permanently interconnecting an intermediate portion of said further discharge duct and said cushion space for equalizing static pressures obtaining respectively thereat.

8. A machine as claimed in claim 6, further comprising substantially unobstructed fluid passage means permanently interconnecting said intermediate duct portion and an intermediate portion of said further discharge duct for equalizing static pressures obtaining respectively thereat.

9. A-machine as claimed in claim 8, further comprising a further substantially unobstructed fluid-shunting means permanently interconnecting said further duct intermediate portion and said cushion space for equalizing static pressures obtaining respectively thereat.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION June 28, 1971 Patent No. 3 Dated,

Inventor(s) Marc Henri Jean FAURE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 3, line 22, the line should read:

-thereby regulating said area in response to such variations-- Signed and sealed this 28th day of December 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Acting Commissioner of Patents Attesting Officer

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