Boundary layer control system and device

A boundary layer control (BLC) system for embedment in a flight surface having a top surface, a bottom surface, a leading edge, and a trailing edge. The BLC system may comprises an actuator having a crossflow fan and an electric motor to drive the crossflow fan about an axis of rotation. The actuator may be embedded within the flight surface and adjacent the leading edge. In operation, the actuator is configured to output local airflow via an outlet channel through an outlet aperture adjacent the top surface to energize a boundary layer of air adjacent the top surface of the flight surface.

TECHNICAL FIELD

The present disclosure relates to systems and methods to provide boundary layer control; more particularly, to boundary layer control devices for aircraft and marine craft.

BACKGROUND

Aircraft sometimes employ devices to increase lift during flight. Lift is a component of force exerted on an object by a flowing fluid (e.g., air or water) that is perpendicular to the flow direction. Lift is often discussed with respect to a foil, such as an airfoil (e.g., an aircraft wing airfoil) or hydrofoil (e.g., a watercraft hydroplane), or a complete foil-bearing body. Lift is proportional to the density of the fluid, the velocity of the object, and certain properties of the foil, such as its surface area. Lift is also proportional to a lift coefficient (CL), which is a numerical representation of dynamic lift characteristics of the foil. To achieve forward flight, for example, a fixed wing aircraft must generate a certain amount of lift.

Generating lift can be a challenge at slower speeds. All things being equal, the slower an object travels, the less lift that is generated; therefore, a direct relationship existing between speed and lift. This can be an issue when an aircraft is traveling at reduced speeds, such as during take-off and landing. This issue may be compounded in situations where the length or distance of a take-off or landing is reduced, such as on an aircraft carrier or short runway. While it is possible in some situations to increase lift by increasing the surface area of the foil, there are also disadvantageous tradeoffs, such as increased weight and increased drag. Thus, designers have studied ways to increase the lift coefficient to generate more lift at slower speeds while keeping the wing size relatively small. For example, certain boundary layer control (BLC) schemes have been employed to delay boundary layer separation, thereby allowing a higher angle-of-attack and maximizing lift potential (and lift coefficient). Existing BLC schemes are not practical, nor are they economical.

In view of the foregoing, a need exists for an improved systems and methods for providing boundary layer control. For example, a need exist for practical and economical boundary layer control devices for embedment in the airfoil of air and marine craft.

SUMMARY

The present disclosure is directed to systems and methods to provide boundary layer control; more particularly, to boundary layer control devices for embedment in the airfoil of aircraft and marine craft.

According to a first aspect, a boundary layer control (BLC) system for a flight surface (the flight surface having a top surface, a bottom surface, a leading edge, and a trailing edge) comprises: an actuator having a crossflow fan and a motor to drive the crossflow fan about an axis of rotation, wherein the actuator is embedded within the flight surface and adjacent the leading edge, wherein the actuator is configured to output local airflow via an outlet channel through an outlet aperture adjacent the top surface to energize a boundary layer of air adjacent the top surface of the flight surface.

In certain aspects, the actuator is configured to ingest the local airflow via an inlet channel through an inlet aperture on the bottom surface.

In certain aspects, the inlet aperture is positioned on the bottom surface to coincide with a stagnation point.

In certain aspects, the flight surface includes at least one movable door configured to close the inlet aperture and the outlet aperture.

In certain aspects, the flight surface includes a slat that is movable between an extended position and a retracted position, wherein the slat defines a leading edge slot in the extended position.

In certain aspects, the outlet aperture is positioned on the leading edge and within the leading edge slot.

In certain aspects, the slat is configured to block the outlet aperture when in the retracted position.

In certain aspects, the actuator is positioned forward of a front spar of the flight surface.

In certain aspects, the axis of rotation is parallel to a portion of the leading edge adjacent the actuator.

In certain aspects, the actuator is battery powered.

In certain aspects, the actuator is generator powered.

In certain aspects, wherein part of the energy expended to drive the actuator is recovered as vectored thrust in the exhaust.

In certain aspects, the BLC system further comprises a second actuator having a second crossflow fan and a second electric motor to drive the second crossflow fan about a second axis of rotation, wherein the second actuator is embedded within the flight surface and adjacent the trailing edge to output local airflow over a knee of a flap coupled at the trailing edge to energize a boundary layer of air adjacent a surface of the flap.

In certain aspects, the second actuator is positioned aft of a rear spar of the flight surface.

In certain aspects, the second axis of rotation is parallel to a portion of the trailing edge adjacent the second actuator.

In certain aspects, the BLC system further comprises a second actuator having a second crossflow fan and a second electric motor to drive the second crossflow fan about a second axis of rotation, wherein the second actuator is configured for embedment within the flight surface and adjacent the trailing edge to output local airflow over a surface of an elevator or a rudder coupled to the trailing edge to energize a boundary layer of air adjacent the surface of the elevator of the rudder.

According to a second aspect, an aircraft having boundary layer control, the aircraft comprises: a fuselage; a wing operatively coupled to the fuselage, wherein the wing includes a top surface, a bottom surface, a leading edge, and a trailing edge; and an actuator having a crossflow fan and a motor to drive the crossflow fan about an axis of rotation, wherein the actuator is embedded within the fixed wing and adjacent the leading edge, wherein the actuator is configured to output local airflow via an outlet channel through an outlet aperture adjacent the top surface to energize a boundary layer of air adjacent the top surface of the fixed wing.

In certain aspects, the actuator is configured to ingest the local airflow via an inlet channel through an inlet aperture on the bottom surface.

In certain aspects, the inlet aperture is positioned on the bottom surface to coincide with a stagnation point.

In certain aspects, the fixed wing includes at least one movable door configured to close the inlet aperture and the outlet aperture.

In certain aspects, the fixed wing includes a slat that is movable between an extended position and a retracted position, wherein the slat defines a leading edge slot in the extended position.

In certain aspects, the outlet aperture is positioned on the leading edge and within the leading edge slot.

In certain aspects, the slat is configured to block the outlet aperture when in the retracted position.

In certain aspects, the actuator is positioned forward of a front spar of the fixed wing.

In certain aspects, the axis of rotation is parallel to a portion of the leading edge adjacent the actuator.

In certain aspects, the actuator is battery powered.

In certain aspects, the actuator is generator powered.

In certain aspects, part of the energy expended to drive the actuator is recovered as vectored thrust in the exhaust.

In certain aspects, the aircraft further comprises a second actuator having a second crossflow fan and a second electric motor to drive the second crossflow fan about a second axis of rotation, wherein the second actuator is embedded within the fixed wing and adjacent the trailing edge to output local airflow over a knee of a flap coupled at the trailing edge to energize a boundary layer of air adjacent a surface of the flap.

In certain aspects, the second actuator is positioned aft of a rear spar of the fixed wing.

In certain aspects, the second axis of rotation is parallel to a portion of the trailing edge adjacent the second actuator.

In certain aspects, the aircraft further comprises a second actuator having a second crossflow fan and a second electric motor to drive the second crossflow fan about a second axis of rotation, wherein the second actuator is embedded within the fixed wing and adjacent the trailing edge to output local airflow over a surface of an elevator or a rudder coupled to the trailing edge to energize a boundary layer of air adjacent the surface of the elevator of the rudder.

According to a third aspect, an aircraft wing comprises: an upper wing surface and a lower wing surface, wherein the upper wing surface and lower wing surface merge into a leading edge and a trailing edge; an actuator having a crossflow fan and a motor to drive the crossflow fan about an axis of rotation, wherein the actuator is embedded between the upper wing surface and the lower wing surface and adjacent the leading edge, wherein the actuator is configured to blow local airflow through an outlet aperture of the leading edge to energize a boundary layer air adjacent the aircraft wing.

In certain aspects, the actuator is configured to ingest the local airflow via an inlet channel through an inlet aperture on the bottom surface.

In certain aspects, the inlet aperture is positioned on the bottom surface to coincide with a stagnation point.

In certain aspects, the fixed wing includes at least one movable door configured to close the inlet aperture and the outlet aperture.

In certain aspects, the fixed wing includes a slat that is movable between an extended position and a retracted position, wherein the slat defines a leading edge slot in the extended position.

In certain aspects, the crossflow fan is operated as a function of sensor data from at least one sensor that reflects one or more flow conditions about the aircraft wing.

In certain aspects, the outlet aperture is positioned on the leading edge and within the leading edge slot.

In certain aspects, the slat is configured to block the outlet aperture when in the retracted position.

In certain aspects, the actuator is positioned forward of a front spar of the fixed wing.

In certain aspects, the axis of rotation is parallel to a portion of the leading edge adjacent the actuator.

In certain aspects, the actuator is battery powered.

In certain aspects, the actuator is generator powered.

In certain aspects, part of the energy expended to drive the actuator is recovered as vectored thrust in the exhaust.

In certain aspects, the aircraft wing further comprises a second actuator having a second crossflow fan and a second electric motor to drive the second crossflow fan about a second axis of rotation, wherein the second actuator is embedded between the upper wing surface and the lower wing surface and adjacent the trailing edge to output local airflow over a knee of a flap coupled at the trailing edge to energize a boundary layer of air adjacent a surface of the flap.

In certain aspects, the second actuator is positioned aft of a rear spar of the fixed wing.

In certain aspects, the second axis of rotation is parallel to a portion of the trailing edge adjacent the second actuator.

In certain aspects, the aircraft wing further comprises a second actuator having a second crossflow fan and a second electric motor to drive the second crossflow fan about a second axis of rotation, wherein the second actuator is embedded between the upper wing surface and the lower wing surface and adjacent the trailing edge to output local airflow over a surface of a control surface coupled to the trailing edge to energize a boundary layer of air adjacent the surface of the elevator of the rudder.

According to a fourth aspect, a boundary layer control (BLC) system for a fixed wing aircraft comprises: a first plurality of fans mounted within a wing, forward of a front spar of the wing, wherein an axis of each of the first plurality of fans is aligned in a span-wise direction, and wherein the first plurality of fans are configured to output local airflow through at least one leading edge slot of the wing to energize a boundary layer air adjacent the surface of the wing; and a second plurality of fans mounted within the wing, aft of a rear spar of the wing, wherein an axis of each of the second plurality of fans is aligned in a span-wise direction, and wherein the second plurality of fans are configured to output local airflow over at least one knee of at least one flap of the wing to energize a boundary layer air adjacent the surface of the wing.

According to a fifth aspect, an aircraft comprises: a fuselage; a wing operatively coupled to the fuselage, wherein the wing includes an upper surface and a lower surface, wherein the upper surface and lower surface merge into a leading edge and a trailing edge, and wherein the leading edge includes a slot; and a fan embedded in the wing, wherein the fan is configured to output local airflow through the slot of the wing to energize a boundary layer of air adjacent the surface of the wing.

DETAILED DESCRIPTION

Preferred embodiments of the present disclosure and other objects, features, and advantages of the devices, systems, and methods described herein will be apparent from the following description of particular embodiments thereof, as illustrated in the accompanying figures, where like reference numbers refer to like or similar structures. The figures are not necessarily to scale, emphasis instead is being placed upon illustrating the principles of the devices, systems, and methods described herein. In the following description, well-known functions or constructions are not described in detail because they may obscure the disclosure in unnecessary detail. For this disclosure, the following terms and definitions shall apply.

The term “aircraft” refers to a machine capable of flight, including, but not limited to, traditional aircraft, unmanned aerial vehicles (UAVs), drones, and vertical take-off and landing (VTOL) aircraft.

The term “composite material” refers to a material comprising an additive material and a matrix material. For example, a composite material may comprise a fibrous additive material (e.g., fiberglass, glass fiber (“GF”), carbon fiber (“CF”), aramid/para-aramid synthetic fibers, FML, etc.) and a matrix material (e.g., epoxies, polyimides, aluminum, titanium, and alumina, including, without limitation, plastic resin, polyester resin, polycarbonate resin, casting resin, polymer resin, thermoplastic, acrylic resin, chemical resin, and dry resin). Further, composite materials may comprise specific fibers embedded in the matrix material, while hybrid composite materials may be achieved via the addition of some complementary materials (e.g., two or more fiber materials) to the basic fiber/epoxy matrix.

The term “exemplary” means serving as a non-limiting example, instance, or illustration. As utilized herein, the terms “e.g.,” and “for example” set off lists of one or more non-limiting examples, instances, or illustrations.

The term “fluid,” when used as a noun, refers to a free-flowing deformable substance with no fixed shape, including, inter alia, gas (e.g., air, atmosphere, etc.), liquid (e.g., water), and plasma.

The term “memory device” means computer hardware or circuitry to store information for use by a processor. The memory device can be any suitable type of computer memory or any other type of electronic storage medium, such as, for example, read-only memory (ROM), random access memory (RAM), cache memory, compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), a computer-readable medium, or the like.

The term “marine craft” refers to a machine capable of operation in water, including, inter alia, vessels capable of operation on top of the water (e.g., boats) and under water (e.g., submarines).

The term “processor” means processing devices, apparatuses, programs, circuits, components, systems, and subsystems, whether implemented in hardware, tangibly embodied software, or both, and whether or not it is programmable. The term “processor” includes, but is not limited to, one or more computing devices, hardwired circuits, signal-modifying devices and systems, devices and machines for controlling systems, central processing units, programmable devices and systems, field-programmable gate arrays, application-specific integrated circuits, systems on a chip, systems comprising discrete elements and/or circuits, state machines, virtual machines, data processors, processing facilities, and combinations of any of the foregoing. The processor may be, for example, any type of general purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, an application-specific integrated circuit (ASIC). The processor may be coupled to, or integrated with, a memory device.

Disclosed herein is a boundary layer control (BLC) system and device to introduce accelerated local and/or ambient fluid from one side of a foil to a boundary layer of a foil (e.g., an airfoil or hydrofoil). The BLC system thus accelerates, energizes, and/or otherwise modifies boundary layer fluid up to and/or past the speed of the free stream in order to delay separation of the boundary layer over the surface of the airfoil or hydrofoil. This delayed separation makes it possible to extend the usable range of angle-of-attack and consequently raises the maximum lift coefficient, thereby allowing for steeper alterations of altitude at reduced speeds without stalling. This increased lift may be especially useful during low speed flight and short take-off and landing (STOL) situations.

In terms of aircraft, a maximum lift coefficient is produced at a critical angle-of-attack. The angle-of-attack is the angle between a reference line of the moving object (e.g., a line defined by the longitudinal length of the fuselage) and a vector representing the relative motion of gas or fluid surrounding the aircraft. As the angle-of-attack increases, the coefficient of lift increases, until the point at which the critical angle-of-attack is reached. As the angle-of-attack increases past the critical angle-of-attack, the flow of air begins to flow less smoothly over the upper surface of the airfoil, and then begins to separate from the upper surface of the airfoil. At the critical angle-of-attack, separated flow can become so dominant that additional increases in the angle-of-attack produce less lift and more drag. Above the critical angle-of-attack, the aircraft is said to be in a stall condition. A stalled aircraft can be dangerous and difficult to control.

The flow of air adjacent the upper surface of an airfoil that separates during stall is called the boundary layer.FIG. 1aillustrates a boundary layer102flowing over an airfoil100. Boundary layer air is sometimes characterized as viscous because it tends to stick to the airfoil100, thus making it slower than the free stream air104outside the boundary layer. Boundary layer separation occurs when the speed of the boundary layer102relative to the airfoil100falls to almost zero.FIG. 1billustrates boundary layer separation. At the point of boundary layer separation, the fluid flow becomes detached from the surface of the airfoil100and creates a turbulent wake106. It can be difficult to maintain lift after boundary layer separation occurs, and the risk of stalling may also increase.

Boundary layer control (BLC) systems, which may be either passive or active, can be employed to delay boundary layer separation; thereby allowing a higher angle-of-attack and maximizing lift potential (and lift coefficient). Leading edge devices (e.g., slats) and trailing edge devices (e.g., flaps) are an example form of passive BLC systems. Active BLC systems generally provide superior lift compared to passive methods by delaying separation of the boundary layer over the top surface of an airfoil using powered systems. Active BLC schemes can involve, inter alia, suction or tapping compressor air from a gas turbine engine to supply bleed air to blow the flaps. Both suction and tapping methods, however, incur significant weight penalties and practical hurdles. For example, boundary layer suction requires thousands of micro-sized holes drilled on the surface of the airfoil. These micro-sized holes are prone to icing and clogging under normal operational conditions. Likewise, boundary layer blowing via bleed air involves ducting high-pressure air from the engine to other parts of the aircraft. Traditional blowing may require substantial heavy ducting because of the extremely elevated bleed air temperatures, as well as the amount of aircraft surface area involved. The ducting may also interfere with the structural layout of the aircraft and limit the mass flow that is available. Additionally, it may deprive the engine of thrust and is dependent upon the engine for thrust. Further, significant pressure losses are associated with the many bends in the ducts required to bring the air from the engines to the BLC nozzles.

Rather than piping air from a distant engine, one or more BLC actuators (e.g., fans driven by electric motors) may be embedded, or otherwise located in, the wing itself to drive air from the local airflow through a leading edge slot (or over the knee of a flap) and to the boundary layer. The size and shape of the BLC actuators may be selected to avoid interference with the wing structure and systems. Because the BLC actuators are separate from the aircraft engine, the revolutions per minute (RPM) of the BLC actuators would not be tied to engine throttle and, therefore, may be separately and independently controlled.

FIG. 2illustrates an example aircraft200according to an aspect of the present disclosure. As illustrated, the aircraft200may generally comprise a fuselage202, a pair of wings204(illustrated as fixed-wings) operatively coupled to the fuselage202, and a tail (or empennage)248operatively coupled to the fuselage202at its aft end. The fuselage202, as illustrated, includes a nose (or forward) portion206and a rear (or aft)208portion. The internal components of the aircraft200are generally covered, concealed, and/or shielded by an external aircraft skin (and/or shell)210, which may be fabricated from a substantially solid aerodynamic material. For example, the aircraft skin210may comprise a metal material, such as, but not limited to, aluminum, titanium, steel, or alloys thereof. Alternatively, or additionally, the aircraft skin210may be constructed using composite material such as, but not limited to, fiberglass. As a further alternative, the aircraft skin210may be a blend of multiple materials.

The wings204serve to produce lift and act as an airfoil during flight. As illustrated inFIG. 3a, the wings204may have internal structural supports. In the example embodiment illustrated in the figures, the wings204include a forward spar220, a central spar222(e.g., a main spar), and a rear (aft) spar224. Each wing204is covered with aircraft skin210to define an upper (top) surface226and a bottom (lower) surface228. The upper surface226and bottom surface228connect and/or merge at (or near—depending on the airfoil shape) a leading edge230and a trailing edge232of the wing204. The internal structural supports of the wing204may be fabricated using a metal, metal alloy, a composite material (or laminate thereof), or combination thereof. For example, a wing204may be fabricated using composite materials through co-curing or composite components connected using metal fittings (e.g., aluminum, titanium, lightweight alloys, etc.).

As illustrated inFIGS. 3band 3c, one or more slats234may be slideably mounted along the leading edge230of the wing204to allow the aircraft200to operate at a higher angle-of-attack and produce a larger lift coefficient during flight. The slats234may be positioned forward from the leading edge230of the wing204and configured to slide along the x-axis away from and relative to the leading edge230(as indicated by the arrow), thereby defining a leading edge (or space)236between the slat234and the leading edge230through which fluid may flow. Alternatively, or additionally, the slat234may be positioned at an elevated and/or raised position such that the top portion of the slat234is raised above the upper surface226of the wing204, or at a drooping and/or lowered position where the bottom surface of the slat234is beneath the bottom surface228of the wing. Alternatively, or additionally, the slat234may be positioned both forward and upward, both forward and downward, or a movable therebetween.

At least one slat support mechanism238is provided to connect the slat234to the wing's204frame (e.g., a rib or spar) to allow the slat234to extend forward and/or to retract backward. In certain aspects, the slat234may be substantially fixed in place and permanently extended away from the leading edge230of the wing204. Alternatively, the slat234may be movable between an extended position where the slat234extends away from the wing204, and a retracted position where the slat234is flush with the wing204, thereby creating a continuous surface with the rest of the wing204and effectively closing and/or shutting the leading edge slot236. When movable, the position and movement of the slat234via the slat support mechanism(s)238may be controlled by a pilot (or another operator) through an electronic or a hydraulic system of the aircraft200, and/or may be configured to automatically respond to aerodynamic forces during flight (e.g., under the control of a flight control system or autopilot).

The aircraft200may further include one or several flaps240along the trailing edge232of the wing204to assist in producing a larger lift coefficient during flight. As illustrated inFIGS. 3aand 3b, the flaps240may be rotatably and/or hingedly connected to the wing204such that the flaps240may pivot up or down relative to the wing204during flight. The flaps240may be configured to rotate about a knee, hinge portion, or joint242. The flaps240may additionally be configured with a mechanism to allow for other, non-rotatable movement, such as, for example, sliding laterally or horizontally. For example, the flaps240may configured as slotted flaps to extend laterally away from the wing204before rotating, thereby creating a trailing edge slot244between the flap240and the wing204. When extended away from the wing204, the flaps240may be supported by at least one flap support mechanism246. The flaps240may be any suitable type known to those of ordinary skill in the art, including, inter alia, normal or plain single element flaps, split flaps, slotted flaps, Fowler flaps, double slotted flaps, triple slotted flaps, Junkers flaps, Gouge flaps, Fairey-Youngman flaps, Zap flaps, and/or Gurney flaps. In some embodiments, the flaps240may be combined with, or replaced by, ailerons or flaperons. The position and movement of the flaps240may be controllable by a pilot or operator and/or automated by an electronic, computer, and/or hydraulic system of the aircraft200, and/or may be configured to automatically respond to aerodynamic forces during flight. Persons of ordinary skill in the art will recognize that alternative and/or additional structural arrangements may be implemented to accommodate the design and/or operational requirements of the aircraft200.

The aircraft200may further include a tail248to, inter alia, produce lift and act as an airfoil during flight. As illustrated inFIG. 2, the tail248may comprise a set of vertical stabilizers216(e.g., dorsal fins) extending vertically from the fuselage202, a rudder218operatively coupled to the vertical stabilizer216, a horizontal stabilizer212supported by the set of vertical stabilizers216to extend laterally from either side of the fuselage202, and elevators214operatively coupled to the horizontal stabilizer212. Depending on the desired tail configuration, the horizontal stabilizer212and vertical stabilizers216may be operatively coupled to one another as well as the fuselage202, or operatively coupled only to the fuselage202. A rudder218may be rotatably and/or hingedly coupled to each vertical stabilizer216to enable the rudder218to move about an axis defined by the vertical stabilizer216at its trailing edge. The rudder218may additionally be configured with a mechanism to allow for other, non-rotatable movement, such as, for example, sliding and/or lateral movement. In alternative embodiments, the rudder218may be coupled to the vertical stabilizer216in such a way as to be substantially fixed in place. In a further alternative, the rudder218may be omitted entirely.

As illustrated inFIG. 4a, the elevators214may be rotatably and/or hingedly coupled to the horizontal stabilizer212to enable movement about an axis defined by the horizontal stabilizer212at its trailing edge. The elevators214may additionally be configured with a mechanism to allow for other, non-rotatable movement, such as, for example, sliding and/or lateral movement. In alternative embodiments, the elevators214may be coupled to the horizontal stabilizer212in such a way as to be substantially fixed in place. In a further alternative, the elevators214may be omitted entirely. In those embodiments where the rudder218and elevators214exist and are movable, the position and movement of the rudder218and elevators214may be controllable by a pilot or operator, automated by an electronic, computer, and/or hydraulic system of the aircraft200, and/or may be configured to automatically respond to aerodynamic forces during flight.

The tail248may be configured in one of multiple tail configurations, including, for example, fuselage mounted, a cruciform, T-tail, a flying tailplane, or, as illustrated inFIGS. 2 and 5, a pi-tail (i.e., π-tail). Therefore, persons of ordinary skill in the art will recognize that alternative and/or additional structural arrangements may be implemented to accommodate the design and/or operational requirements of the tail248. For example, the tail248may instead employ only one vertical stabilizer216and one horizontal stabilizer212, or several vertical stabilizers216and several horizontal stabilizers212, and/or slanted or offset stabilizers that have both horizontal and vertical dimensions. Additionally, or alternatively, the tail248may include multiple rudders218and/or a plurality of elevators214on each horizontal stabilizer212.

FIG. 5illustrates a top plan view of the aircraft ofFIG. 2implementing a plurality of BLC actuators502positioned along the leading and/or trailing edges of the flight surfaces (e.g., the wings204, horizontal stabilizer212, and vertical stabilizers216. More specifically, the aircraft200may be configured with one or more fluid moving BLC actuators502mounted within the wings204and/or tail248. In the exemplary embodiments shown inFIGS. 5 through 7, the BLC actuators502may employ motor-driven blowers, which generally employ a motor and a fan, such as crossflow or tangential fans. The BLC actuators502are configured to blow, push, thrust, propel, and/or otherwise accelerate local or ambient fluid from a first surface of the airfoil to a second surface or skin510of the wings204and/or tail248, which in turn energize, accelerate, and/or otherwise modify the boundary layer condition adjacent to the surfaces of the wings204and/or tail248to mitigate the risk of boundary layer separation. As noted above, mitigating boundary layer separation can extend the usable range of angle-of-attack and, consequently, increase the maximum lift coefficient (CLmax).

In certain aspects, a plurality of BLC actuators502may be mounted in each wing204to provide redundancy and complete coverage. This may be advantageous in a situation where a single BLC actuator502has failed, as there would still be several other BLC actuators502remaining operational. That is, by installing n number of BLC actuators502span-wise in the wing204, the failure of a single BLC actuator502would only rob the wing204of roughly (1/nth) of the total lift derived from the overall BLC system. The BLC actuators502may also be spaced apart span-wise (lengthwise) along the wing204to accommodate wing flexing. Each BLC actuators502may be mounted in the wings204(e.g., beneath the aircraft skin210) with its axis of rotation806substantially aligned in a span-wise direction. The axis of rotation806of each BLC actuator502may further be aligned substantially parallel to the portion of the leading edges230and/or trailing edges532of the wings204that is adjacent the width BLC actuator502(e.g., along the Z-axis). The BLC actuators502may be mounted in close proximity to and/or substantially adjacent to the leading edge230(e.g., adjacent the slats234) and trailing edge232(e.g., adjacent the flaps240) of the wings204. In certain aspects, each slat234may be matched with its own BLC actuators502and/or each flap240may be matched with its own BLC actuators502. For example, each slat234and/or flap240may have a dedicated BLC actuator502, which may be sized to be substantially the same width as the slat234and/or flap240. Alternatively, multiple BLC actuators502may be placed adjacent each slat234and/or flap240, or a single BLC actuator502may be used with multiple slats234and/or flaps240. Alternatively, some slats234and/or flaps240may be matched with a single BLC actuator502, while others are matched with multiple BLC actuators502, while still others share a single BLC actuator502. In some embodiments, some slats234and/or flaps240may not be matched with any BLC actuators502.

Embedded BLC actuators502can achieve reductions in cost, weight, and/or improved performance. Taking a Boeing737for example, the rather extensive high-lift system comprising Krueger flaps and slats on the leading edge, double-slotted Fowler flaps on the trailing edge could be replaced with either plain or single-slotted Fowler flaps and the equivalent of slats, thereby resulting in a system that could delete many moving parts, and most of the flap track fairings which cause several percent points of the total drag in cruise. As a result, the Boeing737's hydraulic system could also be made smaller, or entirely deleted in favor or electric actuators.

FIGS. 6athrough 6dillustrate a cross section of a wing204airfoil taken along line5-5inFIG. 5, further depicting the operation of the BLC actuators502. As illustrated, the wing204airfoil may define a set of chambers to house two BLC actuators502a(leading) and502b(trailing) (collectively, also referred to as502). Leading BLC actuator502amay be positioned aft of the leading edge230and forward (or ahead) of the forward spar220. In one embodiment, as illustrated inFIG. 6d, the leading BLC actuator502amay be positioned substantially adjacent to the leading edge slot236between the leading edge230of the wing204and the slat234. The trailing BLC actuator502bmay be positioned aft of the rear spar224and forward of the trailing edge232; substantially adjacent the flap240at the trailing edge232of the wing204. One or more leading edge and trailing edge apertures504(e.g., strips, slits, slots, or holes) may be positioned on and/or near each of the upper surface226and/or bottom surface228of the wing204.

Each aperture504may be in fluid communication with one or more fluid channels506, which, in turn, may be in fluid communication with a BLC actuator502. The apertures504at the bottom surface228of the wing204can serve as inlets to the BLC actuators502, thereby allowing ambient or local fluid to enter the fluid channel506from the underside of the wing's204airfoil and to be acted upon (e.g., accelerated) by the BLC actuators502. The apertures504at the upper surface226may serve as outlets from the BLC actuators502, which allow the ambient or local fluid that entered through the inlets to be outputted from the BLC actuators502after being acted upon by BLC actuators502. The aperture504at the bottom surface228, the inlet aperture, of leading edge230of the wing502airfoil may be positioned to coincide with a stagnation point of the wing204, thus taking advantage of the higher static pressure.

The fluid channels506may be curved, or otherwise shaped, along their length to better accommodate entry and exit of fluid flow between the BLC actuators502and the upper surface226and/or bottom surface228. Alternatively, the fluid channels506may be straight, corkscrewed, looped, or otherwise shaped according to the desires and designs of the system or airfoil. The apertures504may remain substantially open during forward flight. Alternatively, one or more of the apertures504may be selectively opened and/or closed through movement of the slats234and/or flaps240(as shown in, for example,FIGS. 6cand 6d), through the use of doors or gates, and/or through alternative means. Specifically,FIG. 6cillustrates the wing204having the slat234and flap240in a retracted position (e.g., non-extended), whileFIG. 6dillustrates the slat234and flap240in an extended position. As illustrated, each of the apertures504(top and bottom) on the leading edge230may be blocked (e.g., closed off and/or sealed) by the slat234when the slat234is retracted. Similarly, one aperture504(top) on the trailing edge232may be blocked by the flap240, while the other aperture504(bottom) at the trailing edge232remain open/unobstructed. Further, one or more of the fluid channels506may be provided with a movable door1000to selective block/shut off (e.g., seal) the fluid channels506when not in use to improve airflow over the airfoil and to ensure that the airflow is directed from and to the correct apertures504. The movable door1000may be provided in the channel506adjacent the upper or lower surface of the airfoil, adjacent the BLC actuator502, or a movable door1000may be provided adjacent each of the BLC actuator502and the surface of the vertical stabilizer216.

FIG. 7aillustrates a cross section of an example horizontal stabilizer212airfoil cross section along line6-6inFIG. 5. Each horizontal stabilizer212may have a BLC actuator502positioned within the horizontal stabilizer212and positioned substantially adjacent the elevator214. In alternative embodiments, a plurality of actuators may be positioned within the horizontal stabilizer212, at least one of which may be substantially adjacent to the elevator214. For example, like the wing204, the horizontal stabilizer212may employ both leading and trailing BLC actuators502. Each BLC actuator502may have an axis of rotation806that is aligned substantially parallel to a leading edge230and/or trailing edge232of the horizontal stabilizer212. One or more apertures504may be positioned on and/or near the upper surface226of the horizontal stabilizer212. The aperture504may be in fluid communication with a channel506, which, in turn, may be in fluid communication with BLC actuator502. Similarly, one or more apertures504may be positioned on and/or near the lower surface228of the horizontal stabilizer212, which may be in fluid communication with a channel506, which, in turn, may be in fluid communication with BLC actuator502. The aperture504on and/or near the upper surface226may serve as an inlet to the BLC actuator502, allowing ambient or local fluid to enter the channel506and be acted upon by the BLC actuator502. The aperture504on and/or near the lower surface528may serve as an outlet to the BLC actuator502, allowing the ambient or local fluid that entered through the inlet to be outputted after being acted upon by BLC actuator502. As discussed above with the wing204, the fluid channels506may be curved or otherwise shaped to better accommodate entry and exit of fluid flow. Alternatively, the fluid channels506may be straight, corkscrewed, looped, or otherwise shaped according to the desires and design of the system. The apertures504may remain substantially open most or all of the time during normal operation. Alternatively, some or all of the apertures504may be opened and/or closed through movement of the elevators214(e.g., the aperture may be blocked by the elevator when retracted), through the use of doors or gates, and/or through alternative means.

FIGS. 7band 7cillustrates a cross section of an example vertical stabilizer216along the line7-7inFIG. 5. The vertical stabilizer216may have at least one BLC actuator502positioned within the stabilizer216, in close proximity and/or substantially adjacent to the rudder218. In an alternative embodiment, the vertical stabilizer216may have a plurality of BLC actuators502in close proximity and/or substantially adjacent to the rudder218. The BLC actuators502may have an axis of rotation806aligned substantially parallel to a trailing edge232of the vertical stabilizer216. At least one aperture504may be located on either side surface250a(port),250b(starboard) of the vertical stabilizer216. The apertures504may be in fluid communication with channels506, which, in turn, may be in fluid communication with BLC actuator502.

As illustrated, each side surface250a,250bmay have multiple apertures504in fluid communication with channels506and BLC actuator502. In some embodiments, the BLC actuator502may be configured to use different channels506and/or apertures504depending on the desired direction of the aircraft200and the desired position, movement, and/or angle of the rudder218. Alternatively, or additionally, the BLC actuator502may be configured to change its mode of operation (e.g., reverse its direction of fluid flow) depending on the desired direction of the aircraft200and the desired position, movement, and/or angle of the rudder218. For example, the BLC actuator502may be embodied as a fan and be configured to change its direction and/or rate of spin or rotation depending on the direction of rudder218rotation, the desired direction of the aircraft200, and/or the desired position, movement, and/or angle of the rudder218.

Specifically,FIG. 7billustrates an embodiment where a single BLC actuator502is coupled to four apertures504via four different channels506. In operation, the BLC actuator502may changes it mode of operation to direct airflow from the starboard side surface250bto the port side surface250a(the airflow being show in solid arrows), or vice versa (the airflow being show in dotted arrows). To ensure that the airflow is directed from and to the correct apertures504, each of the fluid channels506may be provided with a movable door1000to selective shut off (e.g., seal) the unused channels. The movable door1000may be provided in the channel506adjacent the surface of the vertical stabilizer216, adjacent the actuator502(e.g., where the chamber housing the BLC actuator502couples to the channel506), or a movable door1000may be provided adjacent each of the actuator502and the surface of the vertical stabilizer216.

Alternatively, a plurality of BLC actuators502may be mounted in the vertical stabilizer216, with some BLC actuators502configured to operate normally, while other BLC actuators502are configured to cease or change operation depending on the direction angle of rudder218rotation, the desired direction of the aircraft200, and/or the desired position, movement, and/or angle of the rudder218. Specifically,FIG. 7cillustrates an embodiment where two BLC actuators502are each separately coupled to two apertures504via two different channels506. In operation, the two BLC actuators502may be independently and separately controlled to direct airflow from the starboard side surface250bto the port side surface250a(the airflow being show in solid arrows), or vice versa (the airflow being show in dotted arrows). As discussed with regard toFIG. 7b, one or more of the fluid channels506may be provided with a movable door1000to selective shut off (e.g., seal) the unused channels to ensure that the airflow is directed from and to the correct apertures504.

As explained above, the fluid channels506may again be curved or rounded to better accommodate entry and exit of fluid flow (e.g., to prevent swirl of air flow). Alternatively, the fluid channels506may be straight, corkscrewed, looped, or otherwise shaped according to the desires and design of the system. The apertures504may remain substantially open most or all of the time during normal operation. Alternatively, the apertures504may be opened and/or closed through movement of the rudder218, through the use of doors or gates, and/or through alternative means. As a further alternative, some of the apertures504may remain substantially open most or all of the time during normal operation while others may be opened and/or closed through movement of the rudder218, and/or through alternative means.

The BLC actuators502may employ, inter alia, motors808(e.g., electric motor) and crossflow/tangential type fans or blower wheels.FIG. 8illustrates an isometric assembly view of a BLC actuator having a crossflow fan. As illustrated, a BLC actuator502may generally comprise a fan wheel800rotatably mounted to a housing assembly801. The fan wheel800generally comprises a plurality of vanes or blades802and one or more circular support disks804. For example, the plurality of blades802may be positioned between a set of outer circular support disks804, where the plurality of blades802are positioned along the circumference of the circular support disks804. Additional circular support disks804may be positioned between the outer circular support disks804to provide additional support and rigidity to the plurality of blades802, thereby preventing the plurality of blades802from bending or warping when a mechanical force (torque) is applied. The blades802of the fan wheel800may be coupled to circular support disks804that revolve around an axis of rotation806. The blades802may be curved to assist in capturing, displacing, accelerating, thrusting, propelling, directing and/or otherwise modifying fluid. The fan wheel800may include a sleeve810at one end and a link812at the other end, whereby the link812is configured to receive a rotational force from a mechanical device (e.g., the motor808) and the sleeve810receives a shaft818.

Crossflow/tangential or blower fan wheels800may be particularly suitable for BLC applications within an aircraft flight surface because of their form factor. Crossflow fans, such as the crossflow fan wheel800illustrated inFIG. 8, have elongated tubular and/or cylindrical profiles. That is, they occupy only a nominal foot print in the X-Y plane to permit embedment in a flight surface, but offer have a significant width (along the Z-Axis), which allows them to cover (whether alone or together with other crossflow fan wheel800) the desired span-wise length of the flight surface.

The housing assembly801generally comprises a set of flanks814(e.g., left and right flanks) separated by a guiding plate816. The width of guiding plate816is sized such that the distance between the set of flanks814accommodates the width of fan wheel800. The shape of the guiding plate816is selected to guide air from one channel506(i.e., the channel506operating as the inlet) to another channel506(i.e., the channel506operating as the outlet). As illustrated, the right side of the fan wheel800is rotatably mounted to the right flank814via a shaft818and bearing assembly820. The bearing assembly820serves to reduce friction between the shaft818and the sleeve810of the fan wheel800. The left side of the fan wheel800is rotatably mounted to the left flank814via the electric motor808(e.g., via its motor shaft) and a motor mount822that secures the electric motor808to the left flank814(e.g., via one or more bolts).

Persons of ordinary skill in the art will understand that alternative embodiments may implement the invention using any suitable fluid moving actuator. For example, alternative embodiments may use a centrifugal fan, a radial fan, an axial fan, a backward curved fan or plug fan, a duplex fan, an impeller, a propeller, a turbine, and/or an electrostatic fluid accelerator. A funnel or other suitable fluid shaping device may be used to channel and shape the fluid flow to the extent necessary to conform the inlets and/or outputs of the BLC actuators502to the aircraft200inlets and/or outlets.

Each BLC actuator502may be driven by one or more electric motors808. Alternatively, multiple BLC actuators502may be mechanically linked to share a single electric motor808. The motor808may be powered by an electrical power supply, including, without limitation, batteries and/or an electrical generator. As a further alternative, the BLC actuators502may be driven by some other suitable mechanism, or may be powered by some other suitable source, as known by those of ordinary skill in the art. The amount of power or energy delivered to the BLC actuators502may be independently controlled and regulated, rather than being tied to the propulsion system of the aircraft200(or other vehicle). For example, the BLC actuators502may be independently controlled and regulated based on sensor data (e.g., representing flow conditions) from one or more sensors. The one or more sensors may include, for example, a Pitot tube, orifice plate, pressure probe, and the like. The sensor data may be analyzed (e.g., by an onboard system) to detect pressure differentials or flow separation. The rotational speed of the BLC actuator502, such as when the actuator employs a fan, for example, can be affected by adjusting the amount of power delivered to the electric motor808, which in turn can affect the amount of fluid that is affected by the BLC actuator502and/or the energy imparted to the fluid. As illustrated inFIG. 9a, power delivery from an electrical power supply902to a BLC actuator may be separately regulated and controlled, such that power for each individual BLC actuator502a-502nmay be raised, lowered, or otherwise altered independently of power level regulation for any other BLC actuator502. Alternatively, as illustrated inFIG. 9b, power level may be more coarsely regulated, such that sets/groups of BLC actuators502a-502n+1 are tied together with respect to raising, lowering, or otherwise altering power delivery. Electrical power from the electrical power supply902may be routed or delivered to the BLC actuators502through electrical wiring and/or other methods as known to those of ordinary skill in the art. Power delivery and/or BLC actuator502operations may be controllable through an actuator controller900.

The actuator controller900may employ, for example, motor drive circuitry and a processor coupled with a memory device. In operation, the processor controls operation of the BLC actuator(s)502via the motor drive circuitry in accordance with instructions from another aircraft system, an operator (e.g., a pilot), and/or instructions (e.g., software) stored to the memory device. The actuator controller900may further be coupled with one or more sensors to provide feedback in real-time (or near real-time) regarding one or more operating parameters of the BLC actuator(s)502(e.g., motor speed, fan speed, airflow speed, temperature, pressure, etc.). For example, a pressure sensor system may be provided to collect a plurality of differential pressure measurements along the span of a wing's leading edge. An example distributed pressure sensor system is described in greater details by commonly owned U.S. Patent Application No. 62/454,188 to Riley Griffin et al., which was filed on Feb. 3, 2017 and is titled “System and Method for Distributed Airflow Sensing.”

Actuator controller900may be controlled by a pilot or operator, automated by an electric and/or computer system of the aircraft200, configured to automatically respond to aerodynamic forces during flight, and/or otherwise controllable through methods known to those of ordinary skill in the art. Therefore the actuator controller900may be communicatively coupled with other aircraft systems, such as the autopilot, aircraft control systems, flight controllers in the cockpit, etc.

A portion of the energy expended to drive the BLC actuators502may recovered as vectored thrust in the exhaust. For example, in operation, fluid may be ingested through the inlet apertures504during flight and channeled to the BLC actuators502. The BLC actuators502, implemented as crossflow fans, for example, may energize or accelerate the fluid to an elevated velocity and output the energized and/or accelerated fluid through the outlet apertures504on the upper surface226of the wings204. The BLC actuators502at the trailing edge232of the wings204may additionally or alternatively output the fluid out over the flap240knees or joints242, and/or across the upper surface226of the wings204and/or flaps240. The output fluid may in turn energize, accelerate, or otherwise modify the boundary layer adjacent the upper surface226of the wings204and/or flaps240. The boundary layer may be accelerated up to and/or past the speed of the free stream in order to delay separation of the boundary layer over the upper surface226of the wing204. This delayed separation can raise the maximum lift coefficient and allow for steeper alterations of altitude using reduced speeds that may have otherwise resulted in the aircraft200stalling.

During flight, fluid may also be ingested through the inlet apertures504in the tail248horizontal stabilizers512and channeled to the BLC actuators502. The BLC actuators502may energize or accelerate the fluid to an elevated velocity and output the energized and/or accelerated fluid through the outlet apertures504on the lower surface528of the horizontal stabilizers512. The BLC actuators502may additionally or alternatively output the fluid out over the elevator214knees or joints242, and/or across the surface528of the horizontal stabilizers512and/or elevators214. The output fluid may in turn energize, accelerate, or otherwise modify the boundary layer adjacent the surface528of the horizontal stabilizers512and/or elevators214. The boundary layer may be accelerated up to and/or past the speed of the free stream in order to delay separation of the boundary layer over the surface528of the horizontal stabilizers512and/or elevators214. This delayed separation can raise the maximum lift coefficient and allow for steeper alterations of altitude using reduced speeds that may have otherwise resulted in the aircraft200stalling.

During flight, fluid may additionally be ingested through the inlet apertures504in the tail248vertical stabilizer216and channeled to the BLC actuator502. The BLC actuator502may energize or accelerate the fluid to an elevated velocity and output the energized and/or accelerated fluid through the outlet aperture504of the vertical stabilizer216. The BLC actuator502may additionally or alternatively blow the fluid out over the rudder218knee or joint242, and/or across the surfaces250a,250bof the rudder218and/or vertical stabilizer216. The output fluid may in turn energize, accelerate, or otherwise modify the boundary layer adjacent the surface250a,250bof the horizontal stabilizers512and/or elevators214. The boundary layer may be accelerated up to and/or past the speed of the free stream in order to delay separation of the boundary layer over the surface250a,250bof the horizontal stabilizers512and/or elevators214. This delayed separation may raise the maximum lift coefficient and allow for steeper alterations of altitude using reduced speeds that may have otherwise resulted in the aircraft200stalling.

During flight, the rudder218may need to provide lift in two different and/or opposite directions. To achieve lift in a first direction, the rudder218may rotate, creating an angle between the rudder and the horizontal stabilizer212defining its axis of rotation. To create lift in an opposite, second direction, the rudder218may rotate in the opposite direction, creating an angle in between the rudder and the horizontal stabilizer212in the opposite direction. Thus, the BLC actuator502may be configured to change its direction of operation, to output fluid on either side of the horizontal stabilizer212, depending on the rotation of the rudder218and the intended resulting lift direction. When implemented as a fan, for example, the BLC actuator502may be configured to change its direction of rotation when the rudder218changes its lift direction. By changing its direction the BLC actuator502may act on local and/or ambient fluid in the opposite direction and output the fluid on the opposite side of the horizontal stabilizer212. When changing its direction of operation, the BLC actuator502may also change the channel506it uses and/or the apertures504it uses as its inlet and/or outlet aperture. In some embodiments, the fluid channels506and/or apertures504that are not in use may be closed and/or sealed using a movable door, and/or by operation of the rudder218itself.

In some embodiments, multiple BLC actuators502may be used, with the BLC actuators502operating primarily in opposite directions. In such an embodiment, a first actuator may output primarily to one side of the horizontal stabilizer212when appropriate for the intended lift direction of the rudder218, while the second BLC actuator502may cease or substantially reduce its operation. If and when lift is desired in the opposite direction, and the rudder218rotates in the opposite direction, the operations of the BLC actuators502may reverse, with the first BLC actuator502ceasing or substantially reducing its operation, while the second BLC actuator502begins or substantially increases its operation in order to output to the other side of the horizontal stabilizer212. In some embodiments, the fluid channels506and/or apertures504that are not in use may be closed and/or sealed using a movable door, and/or by operation of the rudder218itself.

As noted above, during high speed flight and/or during periods of non-use or reduced usage, the apertures504and/or channels506leading to and/from the BLC actuators502may be closed in order to reduce drag. In some embodiments, the apertures504and/or channels may be closed and/or sealed using a movable door1000, as illustrated, for example, inFIGS. 10aand 10b. In some embodiments, such as those described in relation toFIGS. 6cand 6d, the apertures504and/or channels may be closed and/or sealed by operation of the movable flight surfaces near the apertures504and/or channels506. For instance, the apertures504and channels506associated with the wing204leading edge230BLC actuators502may be closed and/or sealed by the adjacent slats234when the slats234are retracted to their position flush with the rest of the wing204. As a further example, the apertures504and channels506associated with the wing204trailing edge232BLC actuators502may be closed and/or sealed by the adjacent flaps240(and/or ailerons and/or flaperons) when the flaps240are retracted and/or rotated to their position flush and substantially in line with the rest of the wing204, where there is little or substantially no angle formed between the flap240and the wing204. As yet another example, the apertures504and channels506associated with horizontal stabilizer212elevator214BLC actuators502may be closed and/or sealed by the adjacent elevators214when the elevators214are rotated to a position substantially in line with the rest of the horizontal stabilizer212, where there is little or substantially no angle formed between the elevator214and the horizontal stabilizer212.

FIGS. 10aand 10billustrate a gate or slot door1000(e.g., small strip doors) that may be used to close or seal a channel506and/or aperture504leading to a BLC actuator502. Each channel506may be selectively sealed/blocked using a slot door1000.FIGS. 10aand 10beach illustrate the slot doors410transitioning from an open position (i.e., allowing airflow through the channel506) to a closed position (i.e., blocking airflow through the channel506). The slot doors410inFIG. 10b, for example, may be lightly sprung to ensure that they open or close properly. As illustrated in the figures, the door or gate1000may be recessed when the channel506and/or aperture504is open, and may slide, shift, and/or otherwise move into a sealing and/or closing position to close and/or seal the aperture504and/or channel506. Alternatively, or additionally, the door or gate1000may rotate and/or swing into a closing position from a recessed and/or open position. Alternatively, or additionally, the fluid channels506and/or apertures504may be opened and/or closed by any other means known to those of ordinary skill in the art. Opening and closing of the apertures504and/or channels may be controllable by a pilot or operator, automated by an electric and/or computer system, configured to automatically respond to hydrodynamic and/or aerodynamic forces during, and/or otherwise controllable through methods known to those of ordinary skill in the art.

While the BLC actuator502and various BLC schemes have been described primarily in relation to aircraft, the principles are applicable to other devices having an airfoil to pass through a fluid, including marine craft.FIG. 11, for example, illustrates one such alternative embodiment where BLC actuators502are implemented in a marine craft, particularly a submarine1100. The submarine1100may include a sail1112and a main body1102having a forward or bow portion1106and an aft, rear, tail, or stern1108portion. The submarine1100may include one or more vertical tail planes1116near the tail portion1108of the ship. The vertical tail planes1116may include one or more rudders1110rotatably and/or hingedly coupled to the vertical tail planes at a knee or joint, such that the rudders1110may swing about an axis defined by the connection to the vertical tail planes1116. The rudder1110may additionally and/or alternatively be configured with a mechanism to allow for other, non-rotatable movement, such as, for example, sliding movement. In alternative embodiments, the rudder1110may be coupled to the vertical tail planes1116in such a way as to be substantially fixed in place. In a further alternative, the rudder1110may be omitted entirely. The submarine1100may also include hydroplanes or diving planes1104, each having a hydrofoil cross section. A hydrofoil, which shares an overall appearance and purpose with the airfoils of the aircraft200, is a lifting surface, or foil, that operates in water instead of air.

The submarine1100may include diving planes on its sail1112, as well as bow1106diving planes1104and stern1108diving planes. In some embodiments, there may be more or fewer diving planes, depending on the design and desired operation of the ship. The diving planes1104may be rotatably and/or hingedly coupled to the body1102of the ship to allow the ship to pitch its bow1106and/or stern1108up and/or down when it is underwater. In such a case, rotating or tilting the diving planes1104upwards or downwards may affect the lift and/or depth of the submarine1100, and/or may assist in changing the depth of the boat when submerging or surfacing, for example. The position and movement of the diving planes1104and rudders1110may be controllable by a pilot or operator, automated by an electronic and/computer system of the submarine1100, and/or may be configured to automatically respond to hydrodynamic forces during operation.

In operation, the diving planes1104of the submarine1100act as hydrofoils when underwater, similar to the airfoils of an aircraft during flight. Accordingly, one or more BLC actuators502may be similarly mounted in, on, and/or substantially adjacent each diving plane1104of the submarine1100, akin to the BLC actuators502mounted with respect to the wings204and/or horizontal stabilizer212of the previously disclosed aircraft200. In some embodiments, some diving planes1104may have one or more actuators mounted thereon and/or therein, while other diving planes1104have no actuators are mounted thereon and/or therein. For example, the arrangements illustrated and described in connection withFIGS. 6athrough 6dand 7amay be applied to the diving planes1104of the submarine1100. Similarly, the arrangements illustrated and described in connection withFIGS. 7band 7cmay be applied to the rudders1110of the submarine1100.

As can be appreciated, however, water proofing measures may be implemented with the various components of the BLC actuators502. For example, to counter the effects of salt water, the components of the BLC actuators502may be fabricated from non-corrosive material. Moreover, because water has a density that is higher than air, the various components may be scaled up and/or, because weight is of a lesser concern, manufactured using heavier and stronger materials. For example, the BLC actuator502may be embodied as an impeller and be configured to change its direction and/or rate of spin or rotation depending on the direction of rudder1110rotation, the desired direction of the submarine1100, and/or the desired position, movement, and/or angle of the rudder1110.

The above-cited patents and patent publications are hereby incorporated by reference in their entirety. Although various embodiments have been described with reference to a particular arrangement of parts, features, and like, these are not intended to exhaust all possible arrangements or features, and indeed many other embodiments, modifications, and variations may be ascertainable to those of skill in the art. Thus, it is to be understood that the invention may therefore be practiced otherwise than as specifically described above.