Patent Description:
Many conventional hovercraft use a fan with a single discharge volute which provides pressurized air exclusively for the air cushion and vertical lift. Other conventional hovercraft use a fan with a double discharge volute which provides pressurized air for both the air cushion and horizontal thrust generation for craft control.

<CIT> discloses a vehicle with an air-cushion lifting system.

Both of the above-described conventional hovercraft fan arrangements which use either a single discharge volute or a double discharge volute have deficiencies. For example, the single discharge volute hovercraft provides pressurized air for cushion air only. Accordingly, the addition of a separate mechanism for horizontal thrust and craft control greatly increases hovercraft weight, cost, and complexity.

Additionally, the double discharge volute fan arrangement provides pressurized air for both air cushion and horizontal control thrust and enhanced craft control. However, the shape of the double discharge volute purposefully directs (or steers) air flow into two separate air flow passageways, i.e., a first air flow passageway for cushion air and a second air flow passageway for craft control thrust. Such channeling of air flow in the direction of the second air flow passageway lessens air flow to the first air flow passageway. As a result, the shape of the volute is not optimized for cushion air only, even though there are often times when air flow through the second air flow passageway for horizontal craft control is not needed/not used (e.g., while at cruising speed) and thus operation of the double discharge volute is sub-optimal during these times.

In contrast to the above-described conventional hovercraft which use either a single discharge volute or a double discharge volute, improved air-cushion techniques are directed to utilizing an air flow assembly having intermittent thruster capabilities. In particular, the air flow assembly is equipped with a set of guide members that enables transitioning between a full fan mode in which air flow is provided only in one direction (e.g., for vehicle cushioning purposes) and a thruster mode in which air flow is split in multiple directions (e.g., for vehicle cushioning as well as for a horizontal thruster for low speed maneuverability). To this end, the air flow assembly may utilize a volute having a shape optimized to provide air flow in just the full fan mode direction and thus operate in the full fan mode more efficiently than a conventional double discharge volute. Furthermore, the set of guide members may control opening and closing of a secondary duct thus enabling sharing of the air flow in multiple directions during thruster mode (e.g., for simultaneous cushion and thruster). In accordance with some embodiments, during thruster mode, the set of guide members is able to split the air flow by impinging into a central chamber of the volute to peel (or bleed) off air flow for thruster use.

An air flow assembly to provide pressurized air is described, e.g., for use by an air-cushion vehicle (ACV) or other craft. The air flow assembly includes a volute having a central chamber, a lift duct, and a thruster duct. The air flow assembly further includes a set of guide members disposed between the central chamber and the thruster duct, and linkage coupled to the set of guide members. The linkage is constructed and arranged to transition the set of guide members between a closed configuration in which the set of guide members closes an opening between the central chamber and the thruster duct, and an opened configuration in which the set of guide members opens the opening between the central chamber and the thruster duct.

There is provided an air-cushion vehicle according to claim <NUM>.

Such an ACV includes a vehicle frame, a fan supported by the vehicle frame, and an air flow assembly supported by the vehicle frame. The air flow assembly is constructed and arranged to control air flow provided by the fan. The air flow assembly includes:.

The volute includes a first curved periphery portion and a second curved periphery portion which define a spiral (or scroll). The set of guide members, when in the closed configuration, defines an arc that connects the first curved periphery portion and the second curved periphery portion to further define the spiral for laminar air flow from the central chamber into the cushion air lift duct. Accordingly, air flow strength may be maximized and air turbulence may be minimized.

In some arrangements, the central chamber of the volute is constructed and arranged to guide air flow from the fan to the cushion air lift duct. Additionally, the set of guide members, when in the closed configuration, blocks air flow between the central chamber and the vehicle thruster duct. Additionally, the set of guide members, when in the opened configuration, promotes air flow between the central chamber and the vehicle thruster duct.

In some arrangements, the set of guide members, when in the opened configuration, defines a louvered structure that impinges within the central chamber to deflect air flow from the central chamber into the vehicle thruster duct. Such impingement directs more air flow into the vehicle thruster duct compared to merely unblocking the opening (e.g., the louvered structure may actually divert air flow into the vehicle thruster duct).

In some arrangements, the fan is constructed and arranged to rotate about a central fan axis (e.g., the axis of impeller rotation). Additionally, each guide member of the set of guide members is constructed and arranged to pivot about a respective guide axis that is parallel to the central fan axis.

In some arrangements, the set of guide members includes a first guide member (e.g., a front vane or flap) constructed and arranged to pivot about a first guide axis, and a second guide member (e.g., a second vane or flap behind the front vane) constructed and arranged to pivot about a second guide axis which is parallel to the first guide axis. Additionally, the linkage is constructed and arranged to pivot the first guide member in a clockwise direction about the first guide axis while concurrently pivoting the second guide member in a counterclockwise direction about the second guide axis, the counterclockwise direction being opposite the clockwise direction.

In some arrangements, each guide member of the set of guide members has an arc-shaped cross section. Example arc-shaped cross sections include airfoil-shaped cross sections, scoops, curved blades, and the like.

In some arrangements, each guide member of the set of guide members has a front edge and a rear edge. Additionally, when the set of guide members is in the closed configuration, (i) the front edge of a second guide member of the set of guide members is covered by the rear edge of a first guide member of the set of guide members, (ii) the front edge of a third guide member of the set of guide members is covered by the rear edge of the second guide member of the set of guide members, (iii) the front edge of a fourth guide member of the set of guide members is covered by the rear edge of the third guide member of the set of guide members. Furthermore, the first, second, third, and fourth guide members are ordered in series.

In some arrangements, the front end of the first guide member is uncovered when the set of guide members is in the closed configuration. Such a feature enables a portion of the volute to taper towards the thruster duct for influencing air flow while the set of guide members is in the opened configuration. However, while the set of guide members is in the closed configuration, the front end of the first guide member covers the portion of the volute to taper towards the thruster duct to preserve a spiral shape of the volute for optimal air flow towards the lift duct.

In some arrangements, the ACV further includes a controller that moves the linkage from a first position in which the linkage holds the set of guide members in the closed configuration and a second position in which the linkage holds the set of guide members in the opened configuration.

In some arrangements, the vehicle thruster duct has a first end adjacent to the central chamber and a second end distal from the central chamber. Additionally, the first end of the vehicle thruster duct has a rectangular cross section. Furthermore, the second end of the vehicle thruster duct has a circular cross section. Such a geometry is well-suited for coupling with the central chamber (e.g., at the first end) and coupling with thruster-related ducting downstream (e.g., at the second end).

In some arrangements, the AVC further includes a nozzle coupled to the second end of the vehicle thruster duct to direct air flow from the vehicle thruster duct to provide horizontal thrust. The nozzle may be constructed and arranged to rotate <NUM> degrees about a vertical axis. Additionally, the nozzle may be constructed and arranged to deflect air flow from a vertical direction by at least <NUM> degrees (e.g., <NUM> degrees).

There is also provided a method of operating an air-cushion vehicle according to claim <NUM>.

The volute includes a first curved periphery portion and a second curved periphery portion which define a spiral; and wherein the set of guide members, when in the closed configuration, defines an arc that connects the first curved periphery portion and the second curved periphery portion to further define the spiral for laminar air flow from the central chamber into the vehicle lift duct.

Systems and apparatus, circuitry, computer program products, and so on are described. Various methods, electronic and/or mechanical components and the like which are involved in utilizing an air flow assembly with intermittent thruster capabilities are described.

This Summary is provided merely for purposes of summarizing some example embodiments so as to provide a basic understanding of some aspects of the disclosure. Accordingly, it will be appreciated that the above described example embodiments are merely examples and should not be construed to narrow the scope of the disclosure in any way.

The foregoing and other objects, features and advantages will be apparent from the following description of particular embodiments of the present disclosure, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the present disclosure.

An improved technique is directed to utilizing an air flow assembly having intermittent thruster capabilities. In particular, the air flow assembly is equipped with a set of guide members that enables transitioning between a full fan mode in which air flow is provided only in one direction (e.g., exclusively for vehicle cushioning purposes) and a thruster mode in which air flow is split in multiple directions (e.g., for vehicle cushioning as well as for a horizontal thruster for low speed maneuverability). To this end, the air flow assembly may be provisioned with a volute having a shape optimized to provide air flow in just the full fan mode direction only and thus operate more efficiently when providing air flow only for cushion air than a conventional double discharge volute. Furthermore, the set of guide members may control opening and closing of a secondary duct thus enabling sharing of the air flow in multiple directions (e.g., concurrently for cushion and thruster) while in thruster mode. In accordance with certain embodiments, the set of guide members is able to split the air flow by impinging into a central chamber of the volute to divert a stronger air flow for thruster use while in thruster mode.

<FIG> shows a cross sectional view of a single discharge volute <NUM> that provides pressurized cushion air flow for a conventional hovercraft. Such lift enables the hovercraft to hover over land and water with relatively low resistance.

The single discharge volute <NUM> provides pressurized air exclusively for air cushion i.e., lifting a hovercraft in the vertical direction (e.g., for illustration purposes, in the positive Y-direction in <FIG>). Along these lines, a lift fan volute enclosure <NUM> extends around a lift fan <NUM> which generates the air flow within the lift fan volute enclosure <NUM> (identified by the arrows in <FIG>).

It should be understood that the above-described single discharge volute does not have the ability to split the air flow for uses beyond cushion air. Accordingly, functions such as control over craft side force, yaw movement, etc. must be provided via other means such as by additional air propellers. Unfortunately, such other means may involve the addition of significant weight, costs, and/or complexity to the hovercraft.

<FIG> shows a cross sectional view of a double discharge volute <NUM> that provides pressurized air flow for air cushion as well as for craft control. In particular, a lift fan volute enclosure <NUM>, which defines two passageways, extends around a lift fan <NUM> which generates the air flow (identified by the arrows in <FIG>). That is, only half of the volute <NUM> (i.e., the right side) curves to a first passageway at the bottom for cushion air. The other half of the volute (i.e., the left side) curves to a second passageway at the top for use in horizontal craft control.

It should be understood that, due to the shape of the double discharge volute <NUM>, the effectiveness of the double discharge volute <NUM> is significantly diminished when air flow for horizontal craft control is not needed. In particular, while the double discharge volute <NUM> supplies pressurized air flow through only the bottom passageway (e.g., when the top passageway is blocked by a downstream valve), the top portion of the double discharge volute <NUM> does not facilitate air flow to through the bottom passageway. Rather, due to the general symmetry for the air passageways, the top portion may generate undesired turbulence, drag, dampening, uneven air flow, etc. while not in use thus decreasing the efficiency of the double discharge volute <NUM>.

Furthermore, while the double discharge volute <NUM> supplies pressurized air flow through both the bottom and top passageways, half of the air flow is provided for lift and half of the air flow is provided for horizontal craft control. Accordingly, the geometry of the double discharge volute <NUM> effectively doubles the air flow and power requirements when both the first and second passageways are open for air flow.

<FIG> shows a cross sectional view of at least a portion of an improved air flow assembly <NUM> that is capable of providing pressurized air flow through multiple ducts in accordance with certain embodiments. As shown, the air flow assembly <NUM> includes a volute <NUM>, a set of guide members <NUM>, and linkage <NUM>.

In accordance with certain embodiments, the air flow assembly <NUM> mounts to a frame <NUM> (e.g., a base or chassis). Such a frame <NUM> may belong to a larger structure and provide air flow for use by that structure. Along these lines, the larger structure may support and operate a fan <NUM> having an impeller that rotates within the volute <NUM> to generate air flow (e.g., about the Z-axis in <FIG>).

Along these lines, the air flow assembly <NUM> may form part of an air cushion vehicle (ACV) and may provide air flow for both vehicle air cushion (e.g., generation of vertical lift in the positive Y-direction) and vehicle thruster (e.g., horizontal craft control). Further details of the air flow assembly <NUM> will now be provided in the context of an ACV although it should be understood that the air flow assembly <NUM> may be used in other situations such as operating an aerial vehicle, a vehicle in the water, a vehicle that rides on land, other equipment, and so on.

As shown in <FIG>, the volute <NUM> includes a central chamber <NUM>, a first duct <NUM> (e.g., a cushion feed duct), and a second or bleed duct <NUM> (e.g., a vehicle thruster duct). The set of guide members <NUM> is disposed between the central chamber <NUM> and the second duct <NUM> within an opening <NUM>.

Each guide member <NUM> is constructed and arranged to pivot (or hinge) relative to the volute <NUM> such that the set of guide members <NUM> collectively blocks or unblocks the opening <NUM>. Accordingly, each guide member <NUM> may be further referred to as a vane, a damper, a flap, a slat, a wing, a louver element, and so on.

In accordance with some embodiments, one or more of the guide members <NUM> has a non-flat (or non-rectangular) cross section such as a cross section in the shape of an airfoil to facilitate air flow thereby. In certain arrangements, all of the guide members <NUM> have non-rectangular cross sections. Suitable non-rectangular cross sections in accordance with these embodiments include curved shapes, teardrop shapes, concave shapes, scoop shapes, and so on.

In other embodiments, one or more of the guide members <NUM> has a substantially uniform thickness, e.g., as if cut from sheet stock. Nevertheless, such guide members <NUM> may be flat or non-flat (e.g., bent or rolled to have a curve) for enhanced air flow control. It should be understood that the linkage <NUM> is constructed and arranged to operate the set of guide members <NUM>. In particular, the linkage <NUM> is able to maneuver the set of guide members <NUM> between (i) a closed configuration in which the set of guide members <NUM> closes the opening <NUM> between the central chamber <NUM> and the second duct <NUM> and (ii) an opened configuration in which the set of guide members <NUM> opens the opening <NUM> between the central chamber <NUM> and the second duct <NUM>. To this end, a portion of the linkage <NUM> couples to the set of guide members <NUM>, and another portion is in a fixed position relative to the volute <NUM> (e.g., mounted to the volute <NUM>, mounted to the frame <NUM>, etc.).

Moreover, it should be understood that the linkage <NUM> may be able to maintain (e.g., hold) the set of guide members <NUM> at are various orientations to control the degree to which the opening <NUM> is blocked (or unblocked) by the set of guide members <NUM>. One end of the range of operation is <NUM>% blocked. However, the linkage may then <NUM> move the set of guide members <NUM> across a continuous range of movement to <NUM>% blocked, <NUM>% blocked, and so on until the set of guide members <NUM> is in a fully opened configuration.

In accordance with certain embodiments, the linkage <NUM> includes a set of connections and/or actuators which is operated (e.g., mechanically, electrically, electro-mechanically, etc.) by a controller <NUM>. In particular, the controller <NUM> moves the linkage <NUM> from a first position in which the linkage <NUM> holds the set of guide members <NUM> in the closed configuration and a second position in which the linkage holds the set of guide members <NUM> in the opened position.

In some embodiments, the controller <NUM> is capable of operating the linkage <NUM> in a manner that maintains the set of guide members <NUM> at fixed orientations partially between the opened and closed configurations. Such a feature enables the controller <NUM> to richly and robustly regulate the air flow through the second duct <NUM>.

As further shown in <FIG>, the air flow assembly <NUM> further includes a nozzle <NUM> coupled to second duct <NUM> to direct air flow from the second duct <NUM>. In the context of an ACV, such air flow may provide horizontal thrust for craft control of the ACV.

In some embodiments, the nozzle <NUM> is constructed and arranged to rotate <NUM> degrees about a vertical axis <NUM> (e.g., the Y-axis in <FIG>). In some embodiments, the nozzle <NUM> is constructed and arranged to deflect air flow from a vertical direction (e.g., the vertical axis <NUM>) by at least <NUM> degrees (see the arrow <NUM> in <FIG>).

It should be understood that, in contrast to a standard single discharge volute (e.g., see <FIG>) and in accordance with certain embodiments, the air flow assembly <NUM> provides multiple separately ducted air flows. Accordingly, the air flow assembly <NUM> is capable of supplying one air flow for the air cushion and another air flow for a separate use such as horizontal craft control. In the ACV context, such a feature may alleviate the need for a separate horizontal craft control mechanism which therefore reduces weight, cost, complexity, and so on.

Additionally, in contrast to a standard double discharge volute (e.g., see <FIG>) and in accordance with certain embodiments, the volute <NUM> of the air flow assembly <NUM> has a shape that optimizes air flow through a single duct <NUM> (e.g., a cushion air lift duct). In particular, when the set of guide members <NUM> is in the closed configuration, the spiral shape of the central chamber <NUM> remains intact (i.e., the set of guide members <NUM> defines an arc that connects a first curved periphery portion and a second curved periphery portion of the central chamber <NUM>. Accordingly, the fan <NUM> is able to generate smooth air flow along the periphery with reduced velocity and pressure loss. As a result, the air flow assembly <NUM> is more efficient.

Moreover, when the set of guide members <NUM> is in the opened configuration (or in a partially opened configuration), the set of guide members <NUM> is able to peel off just enough air flow through another duct <NUM> (e.g., for thruster operation) without substantially cutting the power requirements for cushion air simply in half. Such operation enables the air flow through the duct <NUM> to be easily regulated without a significant drop in air flow through the first duct <NUM>.

Further details will now be provided with reference to <FIG>. As mentioned earlier, the details of the air flow assembly <NUM> are discussed in the context of an ACV by way of example. <FIG> is a perspective view of at least a portion of the air flow assembly <NUM> in accordance with certain embodiments. <FIG> is a similar perspective view which enables the set of guide members <NUM> to be shown in the closed configuration (e.g., for full fan mode operation by an ACV) in accordance with certain embodiments. <FIG> is a similar perspective view which enables the set of guide members <NUM> to be shown in the opened configuration (e.g., for thruster mode operation by an ACV) in accordance with certain embodiments.

As shown in <FIG>, the air flow assembly <NUM> is suitable for mounting or fastening to a support structure. Along these lines, the volute <NUM> or some other portion may attach to a fastening portion (or base section) <NUM> of the support structure in order to maintain the air flow assembly <NUM> in a fixed position relative to the support structure (e.g., the frame or chassis of a vehicle such as an ACV).

As shown in <FIG> and <FIG>, the set of guide members <NUM> are disposed within the volute <NUM> at the opening <NUM> between the central chamber <NUM> and a duct <NUM>. The linkage <NUM> (<FIG>) is omitted from <FIG> and <FIG> to facilitate viewing of the of guide members <NUM>.

To illustrate certain details and as shown in <FIG>, the set of guide members <NUM> are in the closed configuration. In particular, the set of guide members <NUM> defines an arc that connects a first curved periphery portion <NUM>(<NUM>) and a second curved periphery portion <NUM>(<NUM>) of the central chamber <NUM>. That is, the first curved periphery portion <NUM>(<NUM>) and a second curved periphery portion <NUM>(<NUM>) define a spiral (or curve), and the set of guide members <NUM> while in the closed configuration continues that spiral. As a result, the fan <NUM> (<FIG>) is able to provide laminar air flow along the periphery with little or no disruption/turbulence.

To illustrate certain other details and as shown in <FIG>, the set of guide members <NUM> are in the opened configuration. Such transitioning of the set of guide members between the closed configuration and the opened configuration is controlled by the controller <NUM> (<FIG>).

As shown in <FIG>, the set of guide members <NUM> impinges the flow of air within the central chamber <NUM>. Accordingly, a portion of the air flow along the periphery of the central chamber <NUM> is peeled away and steered into the second duct <NUM>.

As shown in <FIG>, the second duct <NUM> may have a geometry that funnels air flow from the central chamber <NUM> toward the nozzle <NUM>. It should be understood that the length (and perhaps other geometrical aspects) of the second duct <NUM> may vary depending on the particular application and requirements for air flow use.

As further shown in <FIG>, the second duct <NUM> has a first end adjacent to the central chamber <NUM> and a second end distal from the central chamber <NUM>. In accordance with certain embodiments, the first end of the second duct <NUM> has a rectangular cross section thus facilitating mating or smooth integration with the central chamber <NUM>. Additionally, the second end of the second duct <NUM> has a circular (or round) cross section thus facilitating mating to the nozzle <NUM> and assisting with the rotational operation of the nozzle <NUM>. Further details will now be provided with reference to <FIG> and <FIG>.

<FIG> and <FIG> show certain details of the air flow assembly <NUM> in accordance with certain embodiments. <FIG> shows the set of guide members <NUM> disposed in the opened configuration in accordance with certain embodiments. <FIG> shows the set of guide members <NUM> disposed in the closed configuration in accordance with certain embodiments.

With reference to <FIG>, the linkage <NUM> (e.g., operated by a controller <NUM>, also see <FIG>) positions the set of guide members <NUM> in the opened configuration to allow air flow through the opening <NUM>. As shown in <FIG> and in accordance with certain embodiments, each guide member <NUM> has an aerodynamic shape (e.g., an arc-shaped cross section) to facilitate air flow (e.g., see the arrow <NUM>) from the central chamber <NUM> into the second duct <NUM>. In particular, each guide member <NUM> has a leading (or front) edge <NUM>(L) that faces (or moves into) the air flow <NUM> and a trailing (or rear/back) edge <NUM>(T) that faces away from the air flow <NUM>. Although flat surfaces and/or sharp corners are suitable for use for the guide members <NUM>, an aerodynamic shape and/or rounded corners reduce undesired turbulence, etc. that would otherwise lower power, efficiency, and so on.

With reference to <FIG>, the linkage <NUM> positions the set of guide members <NUM> in the closed configuration to block air flow through the opening <NUM>. As shown in <FIG> and in accordance with certain embodiments, the set of guide members <NUM> forms an arc that continues the curvature of the central chamber <NUM> to maintain efficient air flow that is directed out through the first duct <NUM> (e.g., see <FIG>). Accordingly, the set of guide members <NUM> minimizes turbulence thus improving power, efficiency, etc. of the air flow through the first duct <NUM>.

It should be understood that the linkage <NUM> is able to transition the set of guide members <NUM> between the opened configuration (e.g., see <FIG>) and the closed configuration (e.g., see <FIG>). In particular, the linkage <NUM> rotates each guide member <NUM> about a respective guide axis that is parallel to the central fan axis, e.g., the Z-axis in <FIG> and <FIG> (also see the Z-axis in <FIG>). In accordance with certain embodiments, the linkage <NUM> is able to maintain the set of guide members <NUM> at different intermediate angles therebetween to enable air flow regulation.

Additionally, in accordance with certain embodiments, when transitioning the set of guide members from the closed configuration to the opened configuration, the linkage <NUM> rotates at least one guide member <NUM> in a direction that is opposite one or more other guide members <NUM>. As best seen in <FIG>, the first (or leftmost) guide member <NUM> rotates in the counterclockwise direction about the Z-axis (see the arrow <NUM>) when the set of guide members <NUM> from the closed configuration to the opened configuration. However, the other guide members <NUM> rotate in the clockwise direction about the Z-axis (see the arrow <NUM>) when the set of guide members <NUM> from the closed configuration to the opened configuration.

Although the leading edge <NUM>(L) of the first guide member <NUM> is uncovered when the set of guide members <NUM> is in the closed configuration, such a feature enables the leading edge <NUM>(L) of the first guide member <NUM> to sit flush against the volute <NUM> while the set of guide members <NUM> are in the closed configuration for a tighter seal to inhibit air leakage through the opening <NUM> (e.g., see <FIG>). Additionally, such a feature further enables the trailing edge <NUM>(T) of each guide member <NUM> to block the leading edge <NUM>(L) of the following adjacent guide member <NUM> (or the edge of the volute <NUM> at the opening <NUM>) to minimize turbulence while the set of guide members <NUM> is in the closed configuration (e.g., see <FIG>).

It should be understood that the set of guide members <NUM> of the air flow assembly <NUM> is illustrated in <FIG> and <FIG> as having exactly four guide members <NUM> arranged in series by way of example. Such an arrangement serves as an effective louvered structure that prevents air flow into the second duct <NUM> when the set of guide members <NUM> is in the closed configuration, and impinges within the central chamber <NUM> to deflect air flow from the central chamber <NUM> into the second duct <NUM> when the set of guide members <NUM> is in the opened configuration. It should be understood that other arrangements and/or numbers of guide members <NUM> are suitable for use as well (e.g., one, two, three, five, six, and so on). Further detail will now be provided with reference to <FIG>.

<FIG> shows, by way of example, a suitable use case environment for the air flow assembly <NUM>. In particular, <FIG> shows multiple ACVs <NUM>. Each ACV <NUM> includes a vehicle frame, one or more fans supported by the vehicle frame, and one or more air flow assemblies <NUM> supported by the vehicle frame.

As shown and by way of example only, the ACVs <NUM> may have form factors of relatively large military grade amphibious ships such as the LACV-<NUM> (Lighter Air Cushion Vehicle, <NUM> tons). Other types and scales of ACVs include small single-seating hovercraft, racing or cruising style hovercraft, large passenger-carrying and/or vehicle-carrying class ships, and so on. Additionally, it should be understood that vehicles of other sizes and shapes are suitable for use as well. Moreover, other applications are suitable for use as well (e.g., hoverbarges, hovertrains, non-transportation applications, etc.).

In accordance with certain embodiments, there are multiple air flow assemblies <NUM> installed within each ACV <NUM>. For example, in connection with the ACV <NUM> in the forefront, a front starboard side air flow assembly <NUM> provides air flow for cushion air (i.e., generating lift in the positive Y-direction) as well as for horizontal control (i.e., Z-axis control). Likewise, a front port side air flow assembly <NUM> provides air flow for cushion air (i.e., generating lift in the positive Y-direction) as well as for horizontal control (i.e., Z-axis control). In particular, as shown in <FIG>, the forefront ACV <NUM> is equipped with ports <NUM> that utilize air flow from the air flow assemblies <NUM> for horizontal craft control. Further details will now be provided with referenced to <FIG>.

<FIG> shows a procedure <NUM> for operating an ACV in accordance with certain embodiments. Such a procedure <NUM> may be effectuated by a controller <NUM>, e.g., manual controls, computerized circuitry, combinations thereof, etc. (also see <FIG>).

At <NUM>, the controller activates a fan coupled to an air flow assembly of the ACV. Recall that the air flow assembly may include:.

At <NUM>, the controller moves the linkage from a first position to a second position which holds the set of guide members in the closed configuration, the ACV obtaining cushion air flow from the fan through the cushion air lift duct while the linkage is in the second position.

At <NUM>, the controller moves the linkage from the second position to the first position which holds the set of guide members in the opened configuration, the ACV obtaining cushion air flow from the fan through the cushion air lift duct and horizontal thrust from the fan through the vehicle thruster duct while the linkage is in the first position.

As indicated at <NUM>, particular aspects of the procedure <NUM> (or the entire procedure <NUM>) are suitable for other crafts and/or objects. Such structures benefit from efficiencies and capabilities provided by the air flow assembly <NUM>.

As described above, improved air-cushion techniques are directed to utilizing an air flow assembly <NUM> having intermittent thruster capabilities. In particular, the air flow assembly <NUM> is equipped with a set of guide members <NUM> that enables transitioning between a full fan mode in which air flow is provided only in one direction (e.g., for vehicle cushioning purposes) and a thruster mode in which air flow is split in multiple directions (e.g., for vehicle cushioning as well as for a horizontal thruster for low speed maneuverability). To this end, the air flow assembly may utilize a volute <NUM> having a shape optimized to provide air flow in just the full fan mode direction and thus operate in the full fan mode more efficiently than a conventional double discharge volute. Furthermore, the set of guide members <NUM> may control opening and closing of a secondary duct <NUM> thus enabling sharing of the air flow in multiple directions during thruster mode (e.g., for simultaneous cushion and thruster). In accordance with some embodiments, during thruster mode, the set of guide members <NUM> is able to split the air flow by impinging into a central chamber <NUM> of the volute <NUM> to peel (or bleed) off air flow for thruster use.

While various embodiments of the present disclosure have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the present disclosure as defined by the appended claims.

It should be understood that some ACVs use lift fans to provide pressurized air flow to the skirt system and air cushion to achieve the on-cushion condition or hover. When on cushion such an ACV can move over land and water with relatively low resistance. Propulsion is typically provided by air propellers. Directional control is typically provided by rudders behind the propeller, or differential propeller thrust when more than one propeller is installed.

To enhance control, some conventional ACVs also use fans to provide pressurized air directed into nozzles creating a thruster, which can be rotated to provide craft side force and yaw moments. Some conventional ACVs use lift fans with double discharge volutes, simultaneously providing cushion air for lift and air to thrusters for control (about half the fan flow to thrusters, half to the cushion). This arrangement effectively doubles the lift fan air flow and lift power requirements. Thrusters do augment forward thrust; however, air thrusters are less than half as efficient as air propellers in thrust output for a given power input.

It should be further understood that, at cruise speeds, the rudders and differential thrust controls can effectively control the craft, maintaining track, and executing maneuvers such as turning or stopping the craft without the need for thrusters.

However, ACVs may be mainly operated at craft speed most of the time transiting between destinations at cruise condition and a fraction of its time in low speed maneuvering condition. Thus, installing continuous fan driven air thrusters, while enhancing control and specifically low speed control, are not necessary during cruise and increases the overall power required, with subsequent increases in required fuel, craft lightship weight, initial cost and lift cycle cost.

In contrast and in accordance with certain embodiments, an improved air flow assembly addresses the above issue by providing an ACV's lift and thrusters with two modes of operation:.

In accordance with certain embodiments, an intermittent thruster may utilize a typical centrifugal fan with single discharge (e.g., see <FIG>), with addition of thruster vanes and a transition duct with a directional nozzle. Such an implementation may utilize thruster vanes with linkages (e.g., see <FIG> and <FIG>). The vanes may be curved asymmetrical air foils. The vanes may be arranged with their axis of rotation parallel to the lift fan impeller shaft. The vanes may be articulated through a series of linkages with an actuator.

In accordance with certain embodiments, with thruster vanes closed (e.g., see <FIG>), the vanes complete the volute scroll inner surface typical of a fan without a thruster. Thus, when closed, the fan performance approaches that of a single discharge, fully dedicated fan. When the thruster vanes are open (<FIG>), the volute resembles a double discharge volute, with a portion of the fan flow directed into the transition duct, then to the nozzle. The nozzle may turn the air about <NUM> degree from vertical towards the horizontal, creating primarily horizontal thrust opposite the direction of discharge. The nozzle may be rotated, generating thrust a full <NUM> degrees in the horizontal plane (e.g., see <FIG>).

In accordance with certain embodiments, the air flow assembly uses thruster vanes shaped to conform the internal surface of the volute, so full single discharge fan performance is achieved when closed (<FIG> and <FIG>). The same curved shape, when rotated along the vane span axis, creates turning vanes, persuading the fan air to flow into the discharge duct, reducing flow losses for improved efficiency. The transition duct located above the thruster vanes, encloses the pressurize thruster air and transitions for the rectangular lift fan opening at the thruster vanes, to the round thruster nozzle bearing surface. The nozzle turns the air from vertical about <NUM> degree towards the horizontal. The nozzle is then rotated on top of the transition duct for directional thrust.

It should be understood that the techniques disclosed herein are suitable for use on various vehicles. Such vehicles include those for general cargo, palletized cargo and wheel vehicle transport ACVs which would benefit from the intermittent thruster invention. Such vehicles may be used in unmanned applications when require enhanced control would partially benefit from the application of intermittent thrusters. Other ACVs that use fans could use the intermittent thruster concept to enhance low speed control.

An air flow assembly is described to provide pressurized air for use by an air-cushion vehicle (ACV). The air flow assembly includes a volute having a central chamber, a vehicle lift duct, and a vehicle thruster duct, a set of guide members disposed between the central chamber and the vehicle thruster duct, and linkage coupled to the set of guide members, the linkage being constructed and arranged to transition the set of guide members between a closed configuration in which the set of guide members closes an opening between the central chamber and the vehicle thruster duct and an opened configuration in which the set of guide members opens the opening between the central chamber and the vehicle thruster duct.

The central chamber of the volute may be constructed and arranged to guide air flow from a fan to the vehicle lift duct. Additionally, the set of guide members, when in the closed configuration, blocks air flow between the central chamber and the vehicle thruster duct. Furthermore, the set of guide members, when in the opened configuration, promotes air flow between the central chamber and the vehicle thruster duct.

The volute is described to include a first curved periphery portion and a second curved periphery portion which define a spiral. Additionally, the set of guide members, when in the closed configuration, defines an arc that connects the first curved periphery portion and the second curved periphery portion to further define the spiral for laminar air flow from the central chamber into the vehicle lift duct.

The set of guide members, when in the opened configuration, may define a louvered structure that impinges within the central chamber to deflect air flow from the central chamber into the vehicle thruster duct.

The fan may be constructed and arranged to rotate about a central fan axis. Additionally, each guide member of the set of guide members is constructed and arranged to pivot about a respective guide axis that is parallel to the central fan axis.

The set of guide members may include a first guide member constructed and arranged to pivot about a first guide axis, and a second guide member constructed and arranged to pivot about a second guide axis which is parallel to the first guide axis. Additionally, the linkage is constructed and arranged to pivot the first guide member in a clockwise direction about the first guide axis while concurrently pivoting the second guide member in a counterclockwise direction about the second guide axis, the counterclockwise direction being opposite the clockwise direction.

Each guide member of the set of guide members my have an arc-shaped cross section.

Each guide member of the set of guide members may have a front edge and a rear edge. Additionally, when the set of guide members is in the closed configuration, (i) the front edge of a second guide member of the set of guide members may be covered by the rear edge of a first guide member of the set of guide members, (ii) the front edge of a third guide member of the set of guide members may be covered by the rear edge of the second guide member of the set of guide members, (iii) the front edge of a fourth guide member of the set of guide members may be covered by the rear edge of the third guide member of the set of guide members. Furthermore, the first, second, third, and fourth guide members may be ordered in series.

The front end of the first guide member may be uncovered when the set of guide members is in the closed configuration.

A controller may move the linkage from a first position in which the linkage holds the set of guide members in the closed configuration and a second position in which the linkage holds the set of guide members in the opened configuration.

The vehicle thruster duct may have a first end adjacent to the central chamber and a second end distal from the central chamber. Additionally, the first end of the vehicle thruster duct may have a rectangular cross section. Furthermore, the second end of the vehicle thruster duct may have a circular cross section.

A nozzle may be coupled to the second end of the vehicle thruster duct to direct air flow from the vehicle thruster duct to provide horizontal thrust.

The nozzle may be constructed and arranged to rotate <NUM> degrees about a vertical axis.

The nozzle may be constructed and arranged to deflect air flow from a vertical direction by at least <NUM> degrees.

An air cushion vehicle (ACV) is described having a vehicle frame, a fan supported by the vehicle frame, and the described air flow assembly and any described modifications.

A method of operating an air-cushion vehicle (ACV) is described, the ACV being as described.

A method of operating an air flow assembly is described. The air flow assembly is as described.

Another method of operating an ACV is described. The method includes activating a fan coupled to an air flow assembly of the ACV, the air flow assembly including:.

Claim 1:
An air-cushion vehicle, ACV, (<NUM>) comprising:
a vehicle frame (<NUM>);
a fan (<NUM>) supported by the vehicle frame; and
an air flow assembly (<NUM>) supported by the vehicle frame, the air flow assembly being constructed and arranged to control air flow provided by the fan, the air flow assembly including:
a volute (<NUM>) having a central chamber (<NUM>), a vehicle lift duct (<NUM>), and a vehicle thruster duct (<NUM>),
a set of guide members (<NUM>) disposed between the central chamber and the vehicle thruster duct, and
linkage (<NUM>) coupled to the set of guide members, the linkage being constructed and arranged to transition the set of guide members between a closed configuration in which the set of guide members closes an opening between the central chamber and the vehicle thruster duct and an opened configuration in which the set of guide members opens the opening between the central chamber and the vehicle thruster duct;
wherein the volute includes a first curved periphery portion (<NUM>(<NUM>)) and a second curved periphery portion (<NUM>(<NUM>)) which define a spiral; and
wherein the set of guide members, when in the closed configuration, defines an arc that connects the first curved periphery portion and the second curved periphery portion to further define the spiral for laminar air flow from the central chamber into the vehicle lift duct.