Feathering propeller clutch mechanisms

Aerial vehicles are equipped with propellers having clutch mechanisms that contract around a shaft when the propellers are not rotating, or are rotating at low angular velocities, and expand around the shaft when the propellers are rotating at sufficiently high angular velocities. The clutch mechanisms surround one or more fixed posts within an opening or window defined therein. When the clutch mechanisms contract into a closed position, components of the clutch mechanisms come into contact with the posts, and the propellers are forced to remain in an alignment defined by the posts. When the clutch mechanisms expand into an open position, such components may rotate freely without contacting the posts. The clutch mechanisms cause propellers to remain aligned in desired orientations when the propellers are not required for operation, thereby reducing drag or adverse acoustic effects.

BACKGROUND

The use of unmanned aerial vehicles such as helicopters having two or more propellers is increasingly common. Such vehicles, which may include quad-copters (e.g., a helicopter having four rotatable propellers), octo-copters (e.g., a helicopter having eight rotatable propellers), or other vertical take-off and landing (or VTOL) aircraft having two or more propellers, are frequently utilized in numerous personal, commercial or industrial applications.

The availability of excess lift is most essential during take-off and landing evolutions of an unmanned aerial vehicle. Precision control of altitude is critical when an unmanned aerial vehicle attempts to take off from or land at a given location, in order to enable the unmanned aerial vehicle to avoid any surrounding objects, structures, animals (e.g., humans) or other unmanned aerial vehicles that may be located nearby. Accordingly, multi-rotor unmanned aerial vehicles are commonly equipped with greater lift capacity than is commonly utilized or required during most transiting operations, in order to ensure that sufficient lift is available when needed, primarily in take-offs or landings.

In order to conserve onboard electrical power when excess lift is not desired, the powered rotation of one or more propellers of a unmanned aerial vehicle may be shut down when the unmanned aerial vehicle is transiting, or in a thrust mode, such as after the unmanned aerial vehicle has successfully taken off, and recommenced when the unmanned aerial vehicle prepares to land at a given location. For example, an unmanned aerial vehicle may feature sets of thrust propellers and lift propellers. When a maximum amount of lift is desired, both the thrust propellers and the lift propellers may be operated. When the maximum amount of lift is no longer desired, however, the operation of the lift propellers may be stopped, thereby reducing the amount of electrical power consumed during operations. A propeller that is provided on an operating unmanned aerial vehicle and is at rest may create undesirable drag, however, and restrict the stability of the unmanned aerial vehicle during transiting operations.

DETAILED DESCRIPTION

As is set forth in greater detail below, the present disclosure is directed to propeller clutch mechanisms. More specifically, the systems and methods disclosed herein are directed to spring-biased mechanisms that are mounted in association with propeller blades, e.g., to an attachment plate provided on an underside of a propeller blade. In some embodiments, an aerial vehicle, e.g., an unmanned aerial vehicle, includes a motor having a shaft for rotating a propeller. The shaft extends through a base having one or more posts (or shoulders) that define an axis along which the propeller is to be substantially aligned when the rotation of the propeller is no longer desired. A spring-biased clutch mechanism having a pair of feathering arms (or locking arms) that are rotatably mounted to the propeller and linked by tension springs or other biasing elements is mounted to a planar surface of the propeller, and surrounds a point at which the propeller is joined to the shaft.

When the propeller is not rotating, the feathering arms contract around the shaft, and form a narrow channel within which the posts of the base are received. Thus, when the posts of the base are received within the narrow channel, and the motor is off, the propeller remains substantially aligned along the axis defined by the posts. When the motor is started, and the propeller begins to rotate, the feathering arms are forced open by contact between such arms and the posts until the propeller reaches a sufficiently high angular velocity, e.g., when the angular velocity of the propeller exceeds a predetermined threshold. When the propeller is spinning under power at an angular velocity consistent with normal operations, the biasing force provided by the biasing element is fully overcome by centrifugal forces acting on the feathering arms, and the feathering arms eventually remain open, free of contact with the posts. When the motor is stopped, and the angular velocity of the propeller falls below a predetermined threshold, the feathering arms will begin to contract again before coming into contact with the posts, and the propeller will eventually come to a stop, aligned along the axis defined by the posts.

Therefore, in accordance with the present disclosure, a spring-biased clutch mechanism may have a closed position in which feathering arms narrowly surround one or more posts mounted to a base, and cause the propeller to remain in an axial orientation defined by the posts, and an open position in which the feathering arms extend beyond the posts, enabling the propeller to rotate freely about a shaft at a sufficiently high rotational velocity. The spring-biased clutch mechanisms may therefore cause a propeller to be aligned in a predefined orientation (e.g., along a predefined axis) when a motor to which the propeller is joined is not operating, without the use of any further electrical or mechanical devices or components. The predefined orientation may be selected on any basis, including but not limited to drag, acoustic or other operational considerations.

Referring toFIGS. 1A through 1D, portions of an aerial vehicle100are shown. The aerial vehicle100includes a propeller105, a clutch mechanism110, a base150, a motor160and a motor mount170. The propeller105is rigidly joined to the motor160by a shaft165that causes the propeller105to rotate in response to a motive force provided by the motor160. The clutch mechanism110is mounted to an attachment plate140, which is itself mounted to one side (e.g., an underside) of the propeller105. The propeller105and the attachment plate140are shown in broken lines.

As is shown inFIGS. 1A through 1D, the clutch mechanism110includes a pair of tension springs120and a pair of feathering arms130. Each of the feathering arms130shown inFIGS. 1A through 1Dhas an angled or tapered shape, e.g., similar to that of a traditional hockey stick, defining an obtuse angle of approximately one hundred thirty-five degrees (135°). As is shown inFIG. 1B, each of the feathering arms130includes a tapered end132and a weighted end134. The feathering arms130are rotatably or pivotably mounted to the attachment plate140using a fastener142of any kind, e.g., threaded screws, nuts, bolts, brads, or any other suitable component by which the feathering arms130may be rotatably joined to the attachment plate140.

The feathering arms130may be formed from any suitable materials. In some embodiments, the feathering arms130may be formed of lightweight metals such as aluminum, metals of heavier weights including alloys of steel, composites, or any other combinations of materials. In some other embodiments, the feathering arms130may be formed from one or more plastics (e.g., thermosetting plastics such as epoxy or phenolic resins, polyurethanes or polyesters, as well as polyethylenes, polypropylenes or polyvinyl chlorides) or woods (e.g., woods with sufficient strength properties such as ash). In still other embodiments, the feathering arms130may be formed from other materials including but not limited to carbon fiber, graphite, machined aluminum, titanium, or fiberglass.

Moreover, portions of the feathering arms130, including but not limited to the tapered end132or the weighted end134, may have any suitable dimensions. For example, as is shown inFIGS. 1A through 1D, the weighted ends134of the feathering arms130may have lengths, widths and/or cross-sectional areas that are larger than the tapered ends132of the feathering arms130. The weighted ends134may be subjected to greater centrifugal forces than the tapered ends132when the feathering arms130are rotated at a sufficiently high angular velocity. In some embodiments, the weighted ends134may include further components such as screws or other fasteners that increase the masses at the corresponding ends of the feathering arms130. Alternatively, in some other embodiments, the weighted ends134may be formed from a material having a greater density than a material from which the tapered ends132are formed, and the weighted ends134may have the same lengths, widths and/or cross-sectional areas as the tapered ends132, thereby also causing the weighted ends134to be subjected to greater centrifugal forces when the feathering arms130rotate at a significantly high angular velocity. The material composition and/or dimensions of the feathering arms130may be manipulated in any manner in order to cause one or more of the operations or effects described herein when the propeller105is rotating or stationary.

Each of the tension springs120may be any type or form of spring or other biasing element to provide a biasing force for urging one of the respective tensioning arms130into a contracted position about the shaft165. As is shown inFIG. 1B, each of the tensioning springs120is joined at a first end to the fastener142rotatably mounting one of the feathering arms130to the attachment plate140and at a second end to the weighted end134of the other of the feathering arms130. In some implementations, the tension springs120may comprise wires having a cross-sectional area of any size or shape (e.g., round, rectangular or square) that is tightly coiled between the fasteners142or other portions of one of the feathering arms130and the weighted ends134of another of the feathering arms130. The tension spring120may thus expand in length, and contract in coil diameter, in response to tensile stresses created by the rotation of the feathering arms130about the fasteners142.

Although the clutch mechanism110ofFIGS. 1A through 1Dincludes a pair of tensioning springs120for biasing the respective feathering arms130, those of ordinary skill in the pertinent arts will recognize that any number of biasing elements, and any biasing elements other than tensioning springs, may be utilized to provide a biasing force to the respective feathering arms130in accordance with the present disclosure, including but not limited to compression springs, extension springs, torsion springs, leaf springs, constant force springs or like elements. For example, in some embodiments, the feathering arms130may be leaf springs that are self-biased into closed positions about a shaft, and may be urged into an open position due to centrifugal forces acting thereon that exceed the biasing forces provided by the leaf springs.

The attachment plate140is mounted beneath the propeller105, and is provided to rigidly join the clutch mechanism110to the propeller105, thereby ensuring that the propeller105and the clutch mechanism110rotate in tandem. As is shown inFIGS. 1B through 1D, the attachment plate140further includes a pair of mechanical stops144, each of which is aligned to come into contact with one of the tapered ends132when one of the feathering arms130has rotated about an axis defined by the fastener142to a maximum extent, thereby resisting further rotation of the feathering arms130. The mechanical stops144may include or comprise one or more posts, screws, nuts, bolts, brads or any other suitable components that may extend from the attachment plate140and/or the propeller105and be aligned to resist rotation of the feathering arms130.

The attachment plate140may be joined to the propeller105via one or more of the fasteners142and/or the mechanical stops144, which may extend through the respective feathering arms130and the attachment plate140, and into the propeller105. Alternatively, the attachment plate140may be joined to the propeller105by any other component or substance, including but not limited to one or more additional fasteners (not shown) or glues or other adhesives. In some embodiments, the clutch mechanism110may be joined to the propeller105directly, and the attachment plate140need not be included as a separate, discrete component.

The base150includes a pair of raised posts (or shoulders)152extending radially outward from a cylindrical platform154provided about an opening155. The base150is mounted to the motor mount170by a plurality of stanchions or other supports, and extends over the motor160. As is shown inFIGS. 1A through 1D, the posts152are formed on the base150and commonly aligned with respect to the opening155in order to define an axis that is substantially parallel to the motor mount170. The shaft165extends between the motor160and the propeller105through the opening155, thereby enabling the posts152to remain fixed in position along the axis with respect to the propeller105.

The motor160is mounted to the motor mount170and includes a shaft165that extends through the opening155and is rigidly joined to the propeller105. In some embodiments, the motor160may be a brushless direct current (DC) motor. In other embodiments, the motor160may be any other type or form of motor, including but not limited to one or more other electric motors, e.g., alternating current (AC) or DC powered motors, as well as any gasoline-powered motors, or motors operating based on any other power or fuel source. In some embodiments, the motor mount170may include all or a portion of a frame of the aerial vehicle100, e.g., a fuselage, one or more wings, or any other component thereof, to which the base150and/or the motor160are mounted. In some embodiments, the base150and/or one or more of the posts152may be mounted directly to a non-rotating portion of the motor160, or in any other location.

The operation of the clutch mechanism110is shown with regard toFIGS. 1B, 1C, and1D. Referring toFIG. 1B, the motor160is stopped, and the propeller105is stationary. As is shown inFIG. 1B, the tension springs120of the clutch mechanism110urge the feathering arms130into a closed position, e.g., with the feathering arms130spaced narrowly apart from one another and defining a window therein, which encompasses the posts152. Thus, when the aerial vehicle100is in flight, but the motor160is stopped, the tension springs120will prevent the propeller105from rotating in response to varying wind flows over and around the aerial vehicle, by maintaining the feathering arms130in the closed position shown inFIG. 1B, and the propeller105will remain aligned in the axis defined by the posts152.

Referring toFIG. 1C, the propeller105is shown as the motor160is started, and the propeller105begins to rotate. Because the clutch mechanism110is joined to the propeller105via the attachment plate140, the clutch mechanism110begins to rotate with the propeller105, causing the posts152to come into contact with inner faces of each of the feathering arms130with each half-cycle rotation of the propeller105. The contact between the posts152and the inner faces of the feathering arms130, and centrifugal force acting on the feathering arms130, e.g., the weighted ends134, forces the feathering arms130to begin to open from the closed position ofFIG. 1Bas the angular velocity of the propeller105begins to increase.

Referring toFIG. 1D, the motor160is shown as causing the propeller105to rotate at an angular velocity above a predetermined threshold. The centrifugal force acting on the weighted ends134causes the feathering arms130to remain in a fully open position, such that the feathering arms130do not come into contact with either of the posts152as the propeller105is rotating. Conversely, when the motor160is brought to a stop, and the angular velocity of the propeller105begins to decrease, the feathering arms130are drawn inward from the fully open position ofFIG. 1Ddue to the biasing force provided by the tension springs120, until the feathering arms130begin to contact the posts152, such as is shown inFIG. 1C. Once the propeller105comes to a complete stop, the feathering arms130are biased into the closed position shown inFIG. 1Bby the tension springs120, with the posts152received therein, and the propeller105will remain aligned along the axis defined by the posts152.

The movement of the feathering arms of one embodiment of a clutch mechanism in accordance with the present disclosure is shown inFIGS. 2A and 2B. Referring toFIGS. 2A and 2B, views of aspects of a propeller clutch mechanism210in accordance with embodiments of the present disclosure are shown. Except where otherwise noted, reference numerals preceded by the number “2” shown inFIG. 2AorFIG. 2Bindicate components or features that are similar to components or features having reference numerals preceded by the number “1” shown inFIGS. 1A through 1D.

As is shown inFIGS. 2A and 2B, the clutch mechanism210includes a pair of tension springs220and a pair of feathering arms230rotatably or pivotably mounted to an attachment plate240by fasteners242. Each of the feathering arms230includes a tapered end232and a weighted end234. The attachment plate240further includes a pair of mechanical stops244, each of which is aligned to stop the rotation of the feathering arms230, and an opening245adapted to receive a shaft (not shown) therein. Each of the tension springs220is connected at a first end to the fastener242that mounts one of the feathering arms230to the attachment plate240and at a second end to the weighted end234of another of the feathering arms230.

As is shown inFIG. 2A, the feathering arms230are in a closed position, e.g., wherein a propeller (not shown) to which the attachment plate240is mounted is stationary, and the tension springs220bias the feathering arms230toward one another, and around a shaft of the propeller. When the feathering arms230are in the closed position ofFIG. 2A, a window for encompassing one or more posts (not shown) that are aligned along a predefined axis is defined between the feathering arms230, such that the propeller remains aligned along the predefined axis until a motor causes the propeller to rotate when the one or more posts are received therein.

As is shown inFIG. 2B, the feathering arms230are in a fully open position, e.g., wherein a propeller (not shown) to which the attachment plate240is mounted rotates at a sufficient angular velocity, such that centrifugal forces acting on the weighted ends234of the feathering arms230exceed the biasing forces applied to the feathering arms230by the tensioning springs220. When the feathering arms230are in the fully open position ofFIG. 2B, the feathering arms230are sufficiently separated, such that the feathering arms230rotate freely of the one or more posts (not shown) between the feathering arms230, and the tapered ends232of the feathering arms230come into contact with the corresponding mechanical stops244.

Those of ordinary skill in the pertinent arts will recognize that the components of the clutch mechanisms of the present disclosure may take any shape or form, and are not limited to the orientations or shapes of the components of the clutch mechanism210shown inFIGS. 2A and 2B. For example, springs or other elements for providing biasing forces to feathering arms and mechanical stops for inhibiting rotation of the feathering arms may be provided as separate or discrete components of the feathering arms or, alternatively, integral to or within such feathering arms. Referring toFIGS. 3A and 3B, views of aspects of a propeller clutch mechanism310in accordance with embodiments of the present disclosure are shown. Except where otherwise noted, reference numerals preceded by the number “3” shown inFIG. 3AorFIG. 3Bindicate components or features that are similar to components or features having reference numerals preceded by the number “2” shown inFIGS. 2A and 2Bor by the number “1” shown inFIGS. 1A through 1D.

As is shown inFIGS. 3A and 3B, the clutch mechanism310includes a pair of feathering arms330rotatably or pivotably mounted to an attachment plate340via fasteners342. Each of the feathering arms330includes a torsion spring320embedded within a rotatable canister-type housing336mounted about one of the fasteners342. Each of the feathering arms330further includes a slot332provided within and extending through the housing336and a weighted end334. The attachment plate340further includes a pair of mechanical stops344in the form of pegs or posts. As is shown inFIGS. 3A and 3B, one of the mechanical stops344is extended into each of the slots332. As is also shown inFIGS. 3A and 3B, each of the weighted ends334of the feathering arms330has a rounded (e.g., concave) surface that conforms to a rounded (e.g., convex) surface of the housing336of another of the feathering arms330.

As is shown inFIG. 3A, the feathering arms330are in a closed position, e.g., wherein a propeller (not shown) to which the attachment plate340is mounted is stationary, and the torsion springs320bias the feathering arms330toward one another, and around a shaft of the propeller. When the feathering arms330are in the closed position ofFIG. 3A, one or more posts (not shown) that are aligned along a predefined axis may be received between the feathering arms330, such that the propeller remains aligned along the predefined axis until a motor causes the propeller to rotate. When the feathering arms330are in the closed position ofFIG. 3A, a window for encompassing one or more posts (not shown) that are aligned along a predefined axis is defined between the feathering arms330, and the rounded surfaces of the weighted ends334and the housings336of opposing arms smoothly mate with one another.

As is shown inFIG. 3B, the feathering arms330are in a fully open position, e.g., wherein a propeller (not shown) to which the attachment plate340is mounted rotates at a sufficient angular velocity, such that centrifugal forces acting on the weighted ends334of the feathering arms330exceed the biasing forces applied to the feathering arms330by the tensioning springs320. When the feathering arms330are in the fully open position ofFIG. 3B, the feathering arms330are sufficiently separated, such that the feathering arms330rotate freely of the one or more posts (not shown) between the feathering arms330.

As is shown inFIGS. 3A and 3B, the rotation of the feathering arms330of the clutch mechanism310is limited by the extent to which the mechanical stops344may rotate within the slots332, which have arcuate shapes corresponding to the shapes of the housings336. For example, each of the feathering arms330may rotate between the closed position ofFIG. 3Aand the open position ofFIG. 3B, each of which is defined by the extent and length of the corresponding slots332within the respective feathering arms330. Rotation of the feathering arms330beyond the open position ofFIG. 3Aor the closed position ofFIG. 3Bis inhibited by contact between the mechanical stops344and internal surfaces of the slots332.

As is discussed above, the clutch mechanisms of the present disclosure may include any type or form of feathering arm (or locking arm) provided in a rotatable or pivotable manner that may defining a window or opening for accommodating posts or shoulders that are aligned along a predefined axis when the feathering arms are in a closed position, and for permitting a propeller to rotate free of contact with such posts when the feathering arms are in a closed position. Those of ordinary skill in the pertinent arts will recognize that the clutch mechanisms of the present disclosure are not limited to the feathering arms230ofFIG. 2A or 2B, or the feathering arms330ofFIGS. 3A and 3B, or any particular arrangement or orientation thereof.

As is discussed above, one or more posts may be provided in a predetermined alignment such that when the posts are received between feathering arms of a clutch mechanism of the present disclosure, and a propeller to which the clutch mechanism is joined falls below a predetermined threshold angular velocity, the feathering arms are biased to positions surrounding the posts, and the propeller comes to a stop in an orientation consistent with the predetermined alignment of the posts. Referring toFIG. 4, a view of aspects of a propeller clutch mechanism in accordance with embodiments of the present disclosure is shown. Except where otherwise noted, reference numerals preceded by the number “4” shown inFIG. 4indicate components or features that are similar to components or features having reference numerals preceded by the number “3” shown inFIGS. 3A and 3B, by the number “2” shown inFIGS. 2A and 2Bor by the number “1” shown inFIGS. 1A through 1D.

As is shown inFIG. 4, a base450includes a pair of raised posts452extending radially outward from a cylindrical platform454provided about an opening455. The base450is mounted to the motor mount470by a plurality of stanchions456or other supports. As is discussed above, the base450is formed in a substantially trapezoidal shape, and may be mounted above a motor (not shown) in a manner that enables a shaft (not shown) of the motor to extend between the motor and a propeller (not shown) through the opening455, thereby enabling the posts452to remain fixed in position with respect to the propeller.

As is also shown inFIG. 4, the posts452are formed on the base450and commonly aligned with the opening455to define an axis. Thus, in some embodiments, when the base450ofFIG. 4is provided in an aerial vehicle (not shown) having a propeller mounted to a shaft (or other propeller mounting structure) extending through the opening455, and the propeller is stationary, the posts452may be received within or between feathering arms of a clutch mechanism (not shown) joined to the propeller that are in a closed position, such that the propeller remains in an orientation consistent with the axis defined by the posts452.

The clutch mechanisms of the present disclosure may be configured to cause a stationary propeller to remain aligned in any orientation or along any axis, and such orientations or axes may be selected on any basis. For example, referring again toFIG. 4, the posts452of the base450may be aligned in a selected axis that is consistent with or parallel to a direction of travel of an aerial vehicle, such that a stationary propeller having a clutch mechanism of the present disclosure is biased into an alignment along the axis. In this regard, the clutch mechanisms of the present disclosure may be used to reduce the drag of an aerial vehicle operating in a thrust mode, e.g., where fewer than all of the propellers provided on the aerial vehicle are required for lift, by aligning propellers that are not required in order to operate in the thrust mode in a direction of travel, thereby reducing drag associated with allowing such propellers to rotate freely. The clutch mechanisms of the present disclosure operate based on biasing forces provided by springs or other biasing elements, and centrifugal forces generated by a rotating propeller, thereby enabling a propeller to be placed in a predetermined alignment without any electrical or powered mechanical components.

As is discussed above, the clutch mechanisms of the present disclosure are rotatable components mounted to or otherwise associated with propellers and are configured to receive one or more stationary components, e.g., posts or shoulders provided on a base or other structural feature, therein. Spatial relationships of the various components of an aerial vehicle including one of the clutch mechanisms of the present disclosure are shown inFIG. e5. Referring toFIG. 5, an exploded view of aspects of an aerial vehicle500including a propeller clutch mechanism510in accordance with embodiments of the present disclosure is shown. Except where otherwise noted, reference numerals preceded by the number “5” shown inFIG. 5indicate components or features that are similar to components or features having reference numerals preceded by the number “4” shown inFIG. 4, by the number “3” shown inFIGS. 3A and 3B, by the number “2” shown inFIGS. 2A and 2Bor by the number “1” shown inFIGS. 1A through 1D.

As is shown inFIG. 5, the aerial vehicle500includes a propeller505, a clutch mechanism510, a base550, and a motor560. The propeller505is rigidly joined to the motor560by a shaft565, which may cause the propeller505to rotate in response to a rotating motive force provided by the motor560. The clutch mechanism510is mounted to an underside of the propeller505by an attachment plate540, and includes a pair of tension springs520and a pair of feathering arms530. The base550is mounted to a motor mount570above the motor560, e.g., by one or more stanchions, and includes a pair of raised posts552extending upwardly above the base550and into an opening defined by the pair of feathering arms530. As is shown inFIG. 5, the posts552are formed on the base550and define an axis that is substantially parallel to the motor mount570. The shaft570extends between the motor560and the propeller505through the opening555, thereby enabling the posts552to remain fixed in position with respect to the propeller505.

Therefore, as is shown inFIG. 5, the aerial vehicle500includes a plurality of rotatable components, including but not limited to the propeller505and the clutch mechanism510, which may be caused to rotate by the motor560, and a plurality of stationary components, including but not limited to the base550, the motor560and the motor mount570, which remain fixed in position without regard to the rotation or position of the propeller505or the clutch mechanism510. One or more of the stationary components, e.g., the posts552provided on the base550, may extend into a window or other opening defined by the feathering arms530of the clutch mechanism510, which are biased into a closed position by the tension springs520. When the motor560is stopped, an angle of orientation of the rotatable components may be defined by the stationary components, e.g., the posts552, extending into the window or opening of the rotatable clutch mechanism510. When the motor560is started, however, the propeller505and the clutch mechanism510begin to rotate, and centrifugal forces cause the feathering arms530to open around the posts552.

As is discussed above, the systems and methods of the present disclosure may be utilized to place a propeller in a preferred alignment when rotation of the propeller is neither desired nor required. The alignment of the propeller may be selected on any basis, including but not limited to drag, acoustic or other operational considerations. For example, a clutch mechanism may be used to cause a propeller to align in a direction of travel of an aerial vehicle when the propeller is not operating. Referring toFIGS. 6A and 6B, views of aspects of an aerial vehicle600including a plurality of propeller clutch mechanisms610A,610B,610C,610D in accordance with embodiments of the present disclosure are shown. Except where otherwise noted, reference numerals preceded by the number “6” shown inFIG. 6AorFIG. 6Bindicate components or features that are similar to components or features having reference numerals preceded by the number “5” shown inFIG. 5, by the number “4” shown inFIG. 4, by the number “3” shown inFIGS. 3A and 3B, by the number “2” shown inFIGS. 2A and 2Bor by the number “1” shown inFIGS. 1A through 1D.

As is shown inFIGS. 6A and 6B, the aerial vehicle600includes a fuselage602, four propellers605A,605B,605C,605D, four clutch mechanisms610A,610B,610C,610D and four motors660A,660B,660C,660D. The propellers605A,605B,605C,605D, the clutch mechanisms610A,610B,610C,610D and the motors610A,610B,610C,610D are joined to the fuselage602by mounts670A,670B,670C,670D.

Referring toFIG. 6A, the aerial vehicle600is shown during lift operations, e.g., where each of the propellers605A,605B,605C,605D and the clutch mechanisms610A,610B,610C,610D are rotated by the motors660A,660B,660C,660D. When the motors660A,660B,660C,660D cause the propellers605A,605B,605C,605D to rotate at a sufficiently high angular velocity, the clutch mechanisms610A,610B,610C,610D are in a fully open position, and the rotation of the propellers605A,605B,605C,605D occurs in an unimpeded fashion during the lift operations shown inFIG. 6A.

Referring toFIG. 6B, the aerial vehicle600is shown during thrust operations, e.g., where only the propellers605A,605B and the clutch mechanisms610A,610B are rotated by the motors660A,660B, and where the motors660C,660D are stopped. Thus, while the rotation of the propellers605A,605B occurs in an unimpeded fashion, without contact between the clutch mechanisms610A,610B and the bases650A,650B, the propellers605C,605D are aligned along axes defined by the bases650C,650D, e.g., by one or more posts or shoulders extending upwardly and into windows or openings defined by the clutch mechanisms610A,610B. More specifically, as is shown with regard to the clutch mechanism610D ofFIG. 6B, feathering arms630D-1,630-D-2are biased into a closed position around the base650D by the tension springs620D-1,620D-2. Thus, because the bases650C,650D define axes that are parallel to or consistent with the direction of travel, the propellers605C,605D aligned along such axes, thereby reducing or minimizing drag or other adverse acoustic conditions that may result if the propellers605C,605D were permitted to drift or freely rotate during thrust operations of the aerial vehicle600.

An axis along which a propeller may be aligned when the rotation of the propeller is no longer desired may be defined or selected on any basis using one or more of the clutch mechanisms of the present disclosure. Additionally, the clutch mechanisms of the present disclosure are not limited for use in helicopter-type aerial vehicles, or unmanned aerial vehicles. Referring toFIGS. 7A and 7B, views of aspects of an aerial vehicle700including a propeller clutch mechanism710in accordance with embodiments of the present disclosure are shown. Except where otherwise noted, reference numerals preceded by the number “7” shown inFIG. 7AorFIG. 7Bindicate components or features that are similar to components or features having reference numerals preceded by the number “6” shown inFIG. 6AorFIG. 6B, by the number “5” shown inFIG. 5, by the number “4” shown inFIG. 4, by the number “3” shown inFIGS. 3A and 3B, by the number “2” shown inFIGS. 2A and 2Bor by the number “1” shown inFIGS. 1A through 1D.

As is shown inFIGS. 7A and 7B, the aerial vehicle700is a fixed-wing aircraft having a fuselage702, a pair of wings770-1,770-2and four propellers705A,705B,705C,705D that may be caused to rotate about shafts driven by one or more motors (not shown) mounted to the wings770-1,770-2. Each of the propellers705A,705B,705C,705D may have a clutch mechanism710A,710B,710C,710D configured to rotate about bases750A,750B,750C,750D that are aligned along predefined axes corresponding to the wings770-1,770-2. Thus, when each of the propellers705A,705B,705C,705D are required for operation of the aerial vehicle700, e.g., in a high-speed or maximum-power evolution, such as is shown inFIG. 7A, each of the clutch mechanisms710A,710B,710C,710D are in a fully open position, and the propellers705A,705B,705C,705D may rotate about the bases750A,750B,750C,750D in an unimpeded fashion.

When the operation of one or more of the propellers705A,705B,705C,705D is neither desired nor required, however, the motors coupled to such propellers705A,705B,705C,705D may be stopped, and the rotation of the corresponding propellers705A,705B,705C,705D is permitted to slow to below a threshold angular velocity. When an angular velocity of one or more of the propellers705A,705B,705C,705D falls below the threshold, the clutch mechanisms710A,710B,710C,710D of such propellers705A,705B,705C,705D contract around their respective shafts and cause such propellers705A,705B,705C,705D to be aligned along axes defined by their respective bases750A,750B,750C,750D. For example, referring toFIG. 7B, motors corresponding to propellers705A,705D are stopped, and the clutch mechanisms710A,710B mounted to propellers705A,705B cause the propellers705A,705D to remain fixed in alignment along axes defined by the bases750A,750D, e.g., corresponding to the angles of orientation of the respective wings770-1,770-2.

Those of ordinary skill in the pertinent arts will recognize that the clutch mechanisms of the present disclosure may be utilized to align propellers along a predefined axis in any manner, on any basis, and for any purpose. For example, referring again toFIG. 7B, the bases750A,750D may be aligned in an axis substantially perpendicular to the respective wings770-1,770-2, so as to minimize any reductions in lift caused by drag due to the non-rotating propellers705A,705D, to enable easier access to motors (not shown) to which such propellers705A,705D are mounted during maintenance evolutions, or for any other purpose.

Although the disclosure has been described herein using exemplary techniques, components, and/or processes for implementing the systems and methods of the present disclosure, it should be understood by those skilled in the art that other techniques, components, and/or processes or other combinations and sequences of the techniques, components, and/or processes described herein may be used or performed that achieve the same function(s) and/or result(s) described herein and which are included within the scope of the present disclosure.

For example, those of ordinary skill in the pertinent arts will recognize that the clutch mechanisms of the present disclosure are not limited to combinations of two feathering arms (or locking arms) and two tension members. Some embodiments of clutch mechanisms provided in association with propellers may include a single feathering arm, e.g., a crescent-shaped feathering arm, having a single tensioning member that enables the single feathering arm to rotate or pivot away from one or more stationary posts or shoulders provided on a base at sufficiently high angular velocities yet causes the single feathering arm to contract around such posts or shoulders at sufficiently low angular velocities, or when a propeller is no longer rotating. Other embodiments of clutch mechanisms of the present disclosure may include three or more feathering arms, each of which may be configured to rotate or pivot away from posts or shoulders, or contract around such posts or shoulders, depending on an angular velocity of a propeller with which such clutch mechanisms are associated. For example, the three or more feathering arms may define a polygonal or continuous shape (e.g., an equilateral triangle or a circle) when such arms are in a closed position, and may contract around one or more stationary posts or shoulders that are arranged in a similar or corresponding shape. Furthermore, tensioning members for biasing such arms may be mounted to any portion of a propeller, an attachment plate, or other rotating component in accordance with the present disclosure.

Furthermore, those of ordinary skill in the pertinent arts will also recognize that the clutch mechanisms disclosed herein may be utilized in connection with propellers having any number of blades, and are not limited to two-bladed propellers. Such propellers may be caused to align along a predefined axis selected on any basis. Additionally, the clutch mechanisms of the present disclosure are also not limited for use on aerial vehicles. For example, a clutch mechanism may be mounted in association with a propeller on a seagoing vessel, and may cause the propeller to align in a preferred orientation, e.g., co-aligned with a rudder or other appurtenance, when rotation of the propeller is no longer desired, thereby reducing not only drag or other adverse flow effects but also a risk of damage to the propeller during slow or abnormal operations, e.g., departing from port, returning to port, or entering a dry-dock. Moreover, the clutch mechanisms may be utilized in connection with one or more other systems for managing flow conditions or reducing drag or acoustic effects caused thereby.

Furthermore, although some of the embodiments disclosed herein reference the use of unmanned aerial vehicles, those of ordinary skill in the pertinent arts will recognize that uses of one or more of the clutch mechanisms disclosed herein are not so limited, and may be utilized in connection with any type or form of aerial vehicle (e.g., manned or unmanned) for which the rotation of a propeller may be desired on a temporary basis, or for less than an entire duration of flight or related operations.

It should be understood that, unless otherwise explicitly or implicitly indicated herein, any of the features, characteristics, alternatives or modifications described regarding a particular embodiment herein may also be applied, used, or incorporated with any other embodiment described herein, and that the drawings and detailed description of the present disclosure are intended to cover all modifications, equivalents and alternatives to the various embodiments as defined by the appended claims. Moreover, with respect to the one or more methods or processes of the present disclosure described herein, orders in which such methods or processes are presented are not intended to be construed as any limitation on the claimed inventions, and any number of the method or process steps or boxes described herein can be combined in any order and/or in parallel to implement the methods or processes described herein. Further, the drawings herein are not drawn to scale.

Although the invention has been described and illustrated with respect to illustrative embodiments thereof, the foregoing and various other additions and omissions may be made therein and thereto without departing from the spirit and scope of the present disclosure.