Surface effect skimmer

A surface effects skimmer vehicle generates a downward air flow into a tunnel under a main hull to lift the main hull off an adjacent surface, and rearward air flows for thrust. The air flows are generated by ducted fans or jet engines, and directed to the rear and/or down by controlling the degree of opening of a Deflector Air Gate (DAG) on the bottom of the main hull. The tunnel includes tunnel edges to contain the downward air flow under the main hull for surface lubrication. The vehicle further includes a rear portion with horizontal and vertical stabilizers to provide air-craft like behavior.

BACKGROUND OF THE INVENTION

The present invention relates to a hovercraft, and most particularly to a surface effect skimming vehicle able to travel at a range of speeds and suitable for both sport and transportation.

Hovercraft are used in various roles including commercial travel, military, and sport uses. By riding on a cushion of air, a hovercraft offers speed, comfort, and avoidance to low obstructions that might prove fatal for a normal water craft. However, known hovercraft require a dedicated lift-fan to provide a cushion of air to support the hovercraft. A skirt of some type is provided, and the hovercraft must remain close to the surface to capture the supporting air within the skirt. The requirement for a skirt limits the design of known hovercraft, and limits the operation to basically remaining parallel to the water surface.

What is needed is a hovercraft capable of providing lift without typical hovercraft limitations.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by providing a surface effects skimmer vehicle which generates a downward air flow into a tunnel under a main hull to lift the main hull off an adjacent surface, and rearward air flows for thrust. The air flows are preferably generated by ducted fans and directed to the rear and/or down by controlling the extent of opening of a Deflector Air Gate (DAG) on the bottom of the main hull and a pair of thrust gates at the rear of ducted fan boxes on each side of the main hull. The tunnel is formed behind the DAG by tunnel edges to contain the downward air flow under the main hull for surface lubrication. The vehicle further includes a rear portion with horizontal and vertical stabilizers to provide air-craft like control.

In accordance with one aspect of the invention, there is provided a surface effects skimmer comprising a main hull suitable for carrying at least one human occupant. The main hull comprises a bow of the main hull, a stern of the main hull, a port side of the main hull, a starboard side of the main hull, a hull centerline running between the bow and the stern, and a hull bottom defining a tunnel open to the stern. The surface effects skimmer includes at least one air flow created by at least one ducted fan or jet engine, which air flow may be directed to provide a rearward thrust and/or a downward air flow. A Deflector Air Gate (DAG) is pivotally attached to the hull bottom proximal to the bow end of the tunnel, wherein the DAG pivots about a DAG leading edge perpendicular to the hull centerline. The downward air flow is regulated and directed into the tunnel by the DAG to reduce drag between the hull bottom and an adjacent surface. The downward air flow may be augmented by a ram-air flow ducted from the bow (e.g., from an air scoop.) A propellor may further reside proximal to the rear of the tunnel and may be driven by the same power source as the ducted fans.

In accordance with another aspect of the present invention, various motor and fan arrangements are contemplated. A single motor in the bow may drive two pairs of port and starboard fans, or a single port and a single starboard fan. A port motor may drive a single port fan or a pair of port fans, and a starboard motor may drive a single starboard fan or a pair of starboard fans. In each case, the motor(s) are preferably coupled to the fans by clutches, and more preferably by centrifugal clutches. Further, the motor and fan combination may be replaced by a turbo fan (e.g., turbo jet) engine or a jet engine.

DETAILED DESCRIPTION OF THE INVENTION

A side view of a surface effects skimmer vehicle10is shown inFIG. 1A, and a top view inFIG. 1B. The vehicle10skims over a surface12and is shown in a configuration suitable for carrying a single occupant, but may be scaled for multiple occupants, or to carry cargo. The main hull14includes a port side14a, starboard side14b, bow end14c, stern end14d, and bottom14e. The main hull14is preferably between approximately 20 feet in length for a single occupant vehicle. The main hull14extends substantially (i.e., extends sufficiently to provide balance to major vehicle10elements) the length of the vehicle10and the hull bottom14edefines a tunnel16under a center portion of the main hull14, which tunnel16includes a tunnel trailing edge18at the rear of the tunnel16, which trailing edge18defines a sharp stern pointing horizontal edge. The tunnel16is preferably between approximately one half and approximately two thirds the length of the main hull14, and preferably between approximately twenty four inches and approximately thirty six inches in width, and more preferably thirty inches in width. The hull bottom14emay be staggered or stepped to create a washboard like surface.

A Deflector Air Gate (DAG)20is attached to the hull bottom14enear a bow end17of the tunnel16, and is preferably approximately the width of the tunnel16, and is preferably approximately square. The forward edge20aof the DAG20is pivotally attached to the hull bottom14e, and is spring loaded in a closed (i.e., lying flat against the hull14) position and may be opened to approximately a twenty degree angle, preferably by setting the pressure of an air-shock. The extent of opening the DAG20both adjusts the contact of the hull14with the surface12, and produces a downward airflow behind the DAG20and into the tunnel16, which downward air flow (seeFIG. 4at 54) provides a lubricating sheet of air between the hull bottom14eand the surface12. The DAG trailing edge20bmay intersect the surface12.

Port and starboard ducted fan boxes22aand22bare attached to the sides14aand14bof the hull14. Port and starboard outriggers24aand24bextends out from the ducted fan boxes22aand22b, and port and starboard outrigger deflection tips26aand26bextend down from the outriggers24aand24b. The outriggers24aand24bmay provide both stability and lift to the vehicle10. The outrigger tips26aand26bextend downward from the outboard edges of the outriggers24aand24b, and help limit the roll of the vehicle10during turns. The outriggers24aand24bpreferably extends outward between approximately sixty percent and approximately ninety percent of the overall vehicle length, and more preferably approximately seventy five percent of the overall vehicle length. The port outrigger deflection tip26aprojects downwardly from the port most edge of the port outrigger24aand the starboard outrigger deflection tip26bprojects downwardly from the starboard most edge of the starboard outrigger24bwherein the outrigger tips are adapted to limit roll when the outrigger tips contact the surface12, wherein the outrigger deflection tips26aand26bpreferably extend downward from the outriggers24aand24bsufficiently to limit vehicle10roll to preferably between approximately ten degrees and approximately twenty degrees, and more preferably approximately fifteen degrees.

Port and starboard horizontal stabilizers34aand34bare attached to the hull stern14d. The horizontal stabilizers34aand34bmay be independently controllable for lift, dive, and split tail control, and may be used to trim the vehicle10. Port and starboard vertical stabilizers32aand32bare attached to the horizontal stabilizers34aand34band may be controlled for turning, and are tilted inward for high speed banking. Port and starboard trolling motors21aand21bare provided for low speed (i.e., docking) maneuvering. The trolling motors21aand21bare mounted behind the port and starboard ducted fan boxes22aand22b, and proximal to the hull bottom14e.

Port and starboard air inlets38aand38breside near the front of the ducted fan boxes22aand22b, and port and starboard thrust gates36aand36breside near the rear of the ducted fan boxes22aand22b. The vehicle10further includes a canopy30and a windshield28. A front view of the vehicle10is shown inFIG. 1C. Port and starboard tunnel edges40aand40bare attached to port and starboard edges of the hull bottom14eto define sides of the tunnel16. The tunnel edges40aand40bare preferably tapered and extend from approximately three inches at the bow end17of the tunnel16to approximately zero inches at the tunnel trailing edge18.

A cross-sectional view taken along line2—2ofFIG. 1Bis shown inFIG. 2. The port thrust gate36ais variable through a first arc37to actively regulate, or in passive response to, a port air flow51a(seeFIG. 3B) generated by a port forward fan42aand port rearward fan44a, resulting in a port rearward thrust52a.

A cross-sectional view of the ducted fan boxes22a,22band main hull14taken along line3—3ofFIG. 1Cis shown inFIG. 3A. The main hull14contains a motor46which drives the port and starboard forward fans42aand42b, and port and starboard rearward fans44aand44b, using port and starboard belts48aand48b. The motor46is preferably an automotive engine, but may be any motor providing sufficient power and meeting weight and size limits, for example, a gas turbine, and is connected to the belts48a,48bthrough a clutch47, which is preferably a centrifugal clutch. A propellor58is connected to the motor46by a propellor shaft60. A rudder62is positioned behind the propellor58. Water and air is ducted to the propellor58from the rear of the tunnel16.

A second cross-sectional view taken along line3—3ofFIG. 1Cis shown inFIG. 3Bdepicting air flow through the main hull14and the port and starboard ducted fan boxes22aand22b. Port and starboard inlet air flows50aand50benter the ducted fan boxes22aand22bthrough the port and starboard air inlets38aand38b(seeFIG. 1B). The air flows50aand50bare accelerated by fans42a,42b,44a, and44bto generate the port and starboard air flows51aand51b. A port rearward thrust52ais derived from the port air flow51a, and a starboard rearward thrust52bis derived from the starboard air flow51b. The amount of thrust52aand52bmay be regulated by controlling the thrust gates36aand36b(seeFIG. 2) or may be a result of the amount of air released by the DAG20(seeFIG. 4).

Continuing withFIG. 3B, a downward air flow54is derived from both air flows51aand51b, and is regulated by the DAG20, and also may be influenced by the thrust gates36aand36b(seeFIGS. 1B and 2). While the rearward thrust has been described herein as port and starboard rearward thrusts, the two rearward thrusts could be combined into a single centered rearward thrust, and a vehicle having a single centered rearward thrust is intended to come within the scope of the present invention.

A cross-sectional view taken along line3C—3C ofFIG. 3Ais shown inFIG. 3C. The propellor58resides under the main hull14and is driven by the motor46through the propellor shaft60. The rudder62is behind the propellor58, which rudder62is on a rudder shaft62a. An inward water flow59aflows into the propellor58, and an outward water flow59bis generated by the propellor58. A lower vertical stabilizer32cresides near the stern of the vehicle10and extends downwardly on a lower vertical stabilizer shaft33from the main hull14.

A side view of the vehicle10showing air flows is shown inFIG. 4. A second arc56of the DAG20is shown, and the downward air flow54is shown as directed by the DAG20. A side view is shown of the starboard inlet air flow50b, the starboard air flow51bcreated by the fans42b,44b, and the resulting starboard rearward thrust52b. If the starboard thrust gate36b(seeFIG. 2) is closed, the starboard air flow51bis substantially directed to the downward flow54.

An embodiment of a ducted fan is shown inFIG. 5A, having single port fan42aand single starboard fan42b. A second embodiment having a port motor46aand a starboard motor46bis shown inFIG. 5B. The port motor46aand starboard motor46bmy be used in cooperation with a single port fan and single starboard fan42aand42b, or with forward and rearward port fans42a,44a, and forward and rearward starboard fans42band44bas shown inFIG. 3Awith a single motor46. Each of the motors46aand46bare preferably connected to the fans42aand42b(and to fans44a, and44bshown inFIG. 3A, when present), and44bthrough clutches47. Each of the motors46aand46bmay independently provide power to both port and starboard ducted fans42a,42b(and to fans44a, and44bshown inFIG. 3A, when present) through belts48aand48b, and to the propellor58. Further, jet motors64aand64bmay be used to provide thrust as shown inFIG. 5C, which jet motors64aand64bmay be any axial flow jet engines, turbojet engines, fanjet engines, turboprop engines, or the like. Embodiments such as those including jet motors64a,64bmay include an air scoop66to generate a scoop air flow54a, as shown inFIG. 6. The downward air flow54(seeFIG. 4) may directly result from the scoop air flow54a.

Aircraft require a balance for force and torque for stable level flight. Similarly, the vehicle10requires a balance of force and torque. Further, a forward (relative to control and lift surfaces) center of gravity (CG)70is desirable for stability, and the CG70is preferably anywhere above the DAG20, and more preferably approximately below the base of the windshield68. A diagram of a preferred distribution of the CG70, vehicle weight vector comprising a first force F1, main lift vector comprising a second force F2, and balancing lift comprising a third force F3are shown inFIG. 7. The forces F1, F2, and F3must add to zero for level flight, and the torques F2*D1and F3*D2must cancel for level flight. To achieve these results, it is preferable to place the motor46near the hull bow14c, as shown inFIG. 3A.

A method for operating a surface effects vehicle according to the present invention is described inFIG. 8. The method comprises the steps of creating a port air flow using a port ducted fan at step80, creating a starboard air flow using a starboard ducted fan at step82, generating a port thrust from the port air flow at step84, generating a starboard thrust from the starboard air flow at step86, controlling a Deflector Air Gate (DAG) to regulate a downward air flow derived from the port air flow and the starboard air flow, at step88, and containing the downward air flow in a tunnel defined by a bottom surface of said vehicle, wherein the downward air flow is controlled by the DAG, a port tunnel edge and a starboard tunnel edge at step90.

While the present invention has been described in terms of a single occupant vehicle10, the invention may equally be embodied in significantly larger vehicles capable of carrying large numbers of occupants, or cargo. The vehicle may also retain or delete the canopy30(seeFIG. 1A). Any surface effect skimmer including at least one ducted fan or jet motor generating an air flow, thrust derived from the air flow, and a downward air flow directed into a tunnel by a DAG20to reduce drag, is intended to come within the scope of the present invention.