Propeller assembly for unmanned aerial vehicles

Abstract

A propeller assembly for unmanned aerial vehicles (UAVs) is disclosed. In one example, a propeller assembly includes a shaft, a first blade coupled to the shaft in a fixed orientation relative to the shaft, and a second blade coupled to slide along the shaft and movable between a first configuration and a second configuration. A pin may couple the second blade to the shaft, the pin engaging a track to move the second blade between configurations with movement of the second blade along the shaft. A spring may bias the pin to a position of the track corresponding to a forward flight orientation of the blades. Movement of the pin along the track may rotate the second blade relative to the first blade to define a hover flight orientation of the blades. Features may be included to reduce slop and / or rattle and transfer impact energy to desired components.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 565,185, filed March 14,2024, entitled “PROPELLER ASSEMBLY FOR UNMANNED AERIAL VEHICLES,” which is incorporated by reference herein in its entirety and for all purposes. FIELD

[0002] The described embodiments relate generally to aerial vehicles, such as unmanned aerial vehicles (UAVs) that may be used to deliver payloads (e.g., packages). BACKGROUND

[0003] Aerial vehicles, such as manned and unmanned vehicles (e.g. airplanes, helicopters, drones, UAVs, etc.), have many uses. Recently, aerial vehicles are becoming a viable option for package delivery vehicles. Such aerial vehicles can take many forms, such as, but not limited to, rotorcraft (e.g., helicopters, quadrotors, and so on) as well as fixed-wing aircraft. Some aerial vehicles can transition between two different flight modes or configurations, such as between a hover flight mode / configuration and a forward flight mode / configuration.

[0004] As aerial vehicles are used more frequently for package deliveries, there is a need for improved overall systems that allow reliable delivery of a package to a delivery location, such as to carry a diverse array of goods in a wide range of environments that create a smooth and pleasant delivery experience for a recipient. In addition, there is a need for the package delivery experience to be quiet, such as to provide a reduction in acoustic emissions. Further, there is a need for a system that provides an ability to transition between flight modes or configurations, such as to improve efficiency and acoustics. SUMMARY

[0005] An example propeller assembly may include a shaft, a first blade coupled to the shaft in a fixed orientation relative to the shaft, a second blade coupled to move along the shaft and movable between a first configuration and a second configuration, and a pin coupling the second blade to the shaft. The pin may engage the shaft to move the second blade between the first configuration and the second configuration with movement of the second blade along the shaft.

[0006] In examples, the propeller assembly may include a track defined in the shaft, the pin moving within the track to move the second blade between the first configuration and the second configuration. The pin may include a first position and a second position relative to a length of the track. The second blade may be in the first configuration based on the first position of the pin. The second blade may be in the second configuration based on the second position of the pin. The propeller assembly may include a spring to bias the pin to either the first position or the second position. The shaft may define an axis of rotation. A first portion of the track may extend parallel to the axis of rotation, the first portion associated with the first position of the pin. A second portion of the track may extend at an angle from the axis of rotation along the shaft, the second portion associated with the second position of the pin. The angle may be 40 degrees. The first configuration may include a first orientation of the second blade relative to the first blade. The second configuration may include a second orientation of the second blade relative to the first blade. The first orientation may be parallel to the first blade. The second orientation may be 60-degrees offset relative to the first blade. The second blade may move between the first configuration and the second configuration based on a lift force generated with a rotation of the second blade.

[0007] An example hub for a propeller assembly movable between a cruise configuration and a hover configuration may include a track having a first portion and a second portion, and a pin engaged with the track to slide along the track between the first portion and the second portion. The pin may be positioned in the first portion to position the propeller assembly in the cruise configuration. The pin may be positioned in the second portion to position the propeller assembly in the hover configuration.

[0008] In examples, the hub may include a spring biasing the pin to the first portion. The hub may include a shaft, wherein the spring is positioned within the shaft to engage the pin. The hub may include a stop limiting a movement of the pin along the track. A gap may be defined between the pin and the track at each of the first portion and the second portion. A propeller assembly may include the hub. The propeller assembly may include a shaft and a first blade coupled to the shaft via the pin, wherein movement of the pin along the track moves the propeller assembly between the cruise configuration and the hover configuration. The propeller assembly may include a second blade coupled to the shaft via a second pin, wherein the second blade is fixed on the shaft, and wherein the first blade moves relative to the second blade via the track. Movement of the pin along the track may both rotate and adjust the axial spacing of the first blade relative to the second blade. A UAV may include the hub.

[0009] An example multi-blade propeller may include a shaft having an axial length, a first blade in a fixed orientation relative to the shaft, a second blade movable between a first orientation relative to the first blade, and a second orientation relative to the first blade, a track defined in the shaft, a first pin coupling the first blade to the shaft, and a second pin coupling the second blade to the shaft. The second pin may engage the track to move the second blade between the first orientation and the second orientation with movement of the second blade along the axial length.

[0010] In examples, the multi-blade propeller may include a nut threaded to the shaft and engaging the first blade. The first blade may be pressed against the nut to limit an impact energy transferred between the first pin and the shaft. The multi-blade propeller may include a first bushing positioned between the first blade and the shaft. The multi-blade propeller may include a second bushing positioned between the second blade and the shaft. The multi-blade propeller may include a flange defined on the shaft, wherein the second bushing presses against the flange when the second blade is in the second orientation. A gap may be defined between the second pm and the track when the second bushing is pressed against the flange. The multi-blade propeller may include a spring biasing the second pin to the first orientation. The shaft may include an internal cavity defined at least partially by an internal taper, and wherein the spring is positioned within the internal cavity to engage the internal taper and the second pin. The first orientation may define a cruise configuration of the multi-blade propeller. The second orientation may define a hover configuration of the multi-blade propeller. A UAV may include the multi-blade propeller.

[0011] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:

[0013] FIG. 1 illustrates an example UAV.

[0014] FIG. 2 illustrates an example UAV including a first aerial vehicle and a second aerial vehicle deployed from the first aerial vehicle.

[0015] FIG. 3 illustrates an example docking assembly for a UAV.

[0016] FIG. 4 illustrates an example UAV in a hover configuration.

[0017] FIG. 5 illustrates an example UAV in a forward flight configuration.

[0018] FIG. 6A illustrates an example propeller assembly in a first configuration.

[0019] FIG. 6B illustrates a partial cross-sectional view of the propeller assembly in the first configuration and taken along line 6B-6B of FIG. 6A.

[0020] FIG. 7A illustrates an example propeller assembly in a second configuration.

[0021] FIG. 7B illustrates a partial cross-sectional view of the propeller assembly in the second configuration and taken along line 7B-7B of FIG. 7A.

[0022] FIG. 8 illustrates an example installation strategy for a fixed blade of a multi-blade propeller.

[0023] FIG. 9 illustrates an example installation strategy' for a folding blade of a multiblade propeller. DETAILED DESCRIPTION

[0024] The descnption that follows includes sample systems, methods, and apparatuses that embody various elements of the present disclosure. However, it should be understood that the described disclosure may be practiced in a variety of forms in addition to those described herein.

[0025] The examples described herein are generally directed to a propeller assembly for a UAV. The examples disclosed herein allow the UAV to transition between multiple flight modes or configurations, such as between a hover mode / configuration and a forward flight or cruise mode / configuration. The UAV may include one or more multi-blade propellers, with multiple blades movable to different positions to accommodate the different flight modes or configurations. For example, the multiple blades may move between an aligned or parallel orientation for forward cruise flight, and an offset orientation for hover flight. The movement of the blades may be facilitated by mechanical means, such as a hub having a track or helix that both translates and rotates a movable blade along a motor shaft relative to a fixed blade. The track or helix may be designed to complement motor specifications, such as to allow the movable blade to open quickly at low speeds for improved efficiency and acoustics, among other benefits. The movable blade may be biased to the aligned / parallel orientation for forward cruise flight, such that the blades snap or otherwise revert to such an orientation automatically for increased performance, efficiency, and / or acoustics in forward flight. The propeller assembly or hub may include other features to reduce slop and / or rattle and transfer impact energy to desired components, such as in both the forward flight configuration and the hover flight configuration.

[0026] The propeller assemblies described herein may be implemented within UAVs or systems utilizing UAVs (e.g., an aerial system). Although described with reference to UAVs, the propeller assemblies may be implemented within manned aerial vehicles and systems. Thus, the propeller assemblies described herein may be implemented with crewed and uncrewed aerial systems. The UAVs may be utilized in a delivery system configured to pick up a payload or a package at a shipping location and deliver a payload or package to a delivery location. It should be noted that while various features and components are discussed with respect to UAVs or UAV systems, the features and components can be used separately from the UAV and / or in various combinations with each other. As such the discussion of any particular implementation is meant as illustrative only.

[0027] An example aerial system is disclosed that may include a first aerial vehicle (e.g., a main or carrier aerial vehicle) and a second aerial vehicle (e.g., a dependent aerial vehicle). In these instances, the first aerial vehicle may act to support and / or transport the second aerial vehicle to a location and the second aerial vehicle can be deployed from the first aerial vehicle, e.g., the second aerial vehicle can be deployed from a first height and descend to a second height or location, such as to deliver a package. In some embodiments, the first aerial vehicle may be able to remain at a high location, such as by hovering, and may reduce the noise, disruption, and safety risks experienced by humans and animals on the ground or delivery location as the second vehicle may be quieter than the first aerial vehicle. In some examples, the first aerial vehicle can be optimized for longer flight paths and the second aerial vehicle can be optimized for an enhanced delivery experience to a human on the ground or delivery location. The payload may be a good or package including consumer goods, food, medical supplies, or other items. Additional variations of the first aerial vehicle and / or the second aerial vehicle may include types of rotorcraft (e.g., helicopters, quadrotors, and so on) or similar vehicles that generate thrust for movement through air, as well as fixed-wing aerial vehicles.

[0028] The locations may include a retail, wholesale, industrial, mail carrier, or other site in which payloads and packages are processed for delivery to a customer. The delivery location may include a package location designated as a specific portion of a building or area, such as a door, a window, a deck, a roof, a parking area, or other locations accessible by a delivery recipient.

[0029] The first aerial vehicle may include flight assemblies enabling different types of flight. For example, the first aerial vehicle may include fixed wings and a cruise propeller configured to forward or cruise flight motion and may also include one or more propeller assemblies configured for hover or similar motion. The cruise propeller may be articulable (e.g. rotatable) between a cruise flight and hover flight position.

[0030] In many embodiments, the second aerial vehicle may be coupled to the first aerial vehicle, e.g., by a tether, cable, or the like. In some embodiments, the second aerial vehicle may be stowed within a portion of the first aerial vehicle, such as a cavity or bay, for a first portion of the mission and deployed and retracted for a second portion of the mission.

[0031] The second aerial vehicle may have separate drive abilities, allowing the second aerial vehicle to steer itself without or to supplement steering by the first aerial vehicle. For example, the second aerial vehicle may include a propulsion assembly allowing the second aerial vehicle to move relative to the first aerial vehicle. The propulsion assembly may include thrusters to provide active control or enable generation of thrust irrespective of the position of the second aerial vehicle.

[0032] The body of the second aerial vehicle may include a volume or feature to house the payload, e.g., a payload bay. In some examples, the payload bay may be accessible through one or more apertures by one or more selectively openable assemblies, such as a lid or doors, to place a payload in the bay or to remove the payload from the bay at the delivery location.

[0033] The aerial vehicles may include one or more sensors that collect data to assist in the operation of the aerial vehicle. For example, the aerial vehicles may include a plurality of sensor assemblies such as audio or sound sensors, visual sensors such as cameras, or the like. The various sensors may be used in combination with processing elements or other systems to navigate. For example, the aerial vehicle may be operated remotely or completely autonomously. The sensors may detect information regarding the environment, such as obstacles, weather information, and the like, and may include a computer and / or be in communication with a processor, to allow the aerial vehicles to make decisions regarding flight, docking, and landing.

[0034] The various computers or processors in communication with the sensors may be associated with machine learned models, databases, or the like to assist in categorizing or understanding sensed information. For example, a machine learned model may be trained to identify objects in images captured by the sensors and the various computing elements may identify flight paths or maneuvers based on the identified objects, or positions of the objects relative to the aerial vehicles. The first aerial vehicle and second aerial vehicle may be in operative communication with each other, such as through wireless networks, cell networks, radio frequencies, wired, or other communication methods.

[0035] Reference will now be made to the accompanying drawings, which assist in illustrating various features of the present disclosure. The following description is presented for purposes of illustration and description. Furthermore, the description is not intended to limit the inventive aspects to the forms disclosed herein. Consequently, variations and modifications commensurate with the following teachings, and skill and knowledge of the relevant art, are within the scope of the present inventive aspects.

[0036] FIGS. 1-2 illustrate an example UAV 100 or aerial vehicle delivery system. The UAV 100 includes various components and systems enabling aerial delivery of a payload, such as packages, food, or other items, to a delivery location. For example, the UAV 100 may be configured for flights over a distance, such as from a pickup location to the delivery location, while carrying or retaining a payload for delivery. At a desired location, such as at the delivery location, the UAV 100 may deliver the pay load, such as through deployment of a portion of the UAV 100, as described herein.

[0037] The UAV 100 may include a first or primary aerial vehicle 102 (hereinafter “first aerial vehicle”). The first aerial vehicle 102 may include a fuselage 106 that defines a housing or body for the first aerial vehicle 102. The fuselage 106 may include a nose 110 portion forming a front end of the first aerial vehicle 102 and a tail 112 portion forming a rear end of the first aerial vehicle 102. The fuselage 106 may generally taper as it extends towards both the tail 112 and the nose 110, although in other configurations, the fuselage 106 may be differently configured. The fuselage 106 may be configured to store various components of the first aerial vehicle 102, such as a payload and / or a second or secondary aerial vehicle 120 (hereinafter “second aerial vehicle”). For example, a vehicle compartment 124 may be defined as a cavity within the fuselage 106, such as on a bottom surface of the fuselage 106, to receive the second aerial vehicle 120 therein. The fuselage 106 (and / or other components of the first aerial vehicle 102) may be configured to include aesthetically pleasing features and elements.

[0038] The first aerial vehicle 102 may include one or more sensors that collect data to assist in the operation of the first aerial vehicle 102. For example, the first aerial vehicle 102 may be operated remotely or completely autonomously by detecting information regarding the environment, such as obstacles, weather information, and the like, and may include a computer and / or be in communication with a processor, to allow the first aerial vehicle 102 to make decisions regarding flight, docking, and landing. With respect to docking, the first aerial vehicle 102 may include a docking assembly 130. The docking assembly 130 may include various structure (e.g., a fin 134 or other structure) to be received or partially inserted within a dock for the first aerial vehicle 102, as described below.

[0039] The first aerial vehicle 102 may include a wing assembly 140 and a tail wing assembly 142. The wing assembly 140 may include multiple wings coupled to the fuselage 106 (e.g., a pair of wings extending from opposite sides of the fuselage 106). The wings may be fixed in position relative to the fuselage 106 and configured to enable a cruise or forward flight motion of the first aerial vehicle 102. The tail wing assembly 142 may extend from or be otherwise coupled to the tail 112. The tail wing assembly 142 may function as a stabilizer for the first aerial vehicle 102 to help stabilize the first aerial vehicle 102 during flight. In one example, the tail wing assembly 142 may be arranged in a V-structure to provide both horizontal and vertical stabilization, but in other embodiments may be differently configured.

[0040] The first aerial vehicle 102 may include one or more propulsion systems (e.g., propeller assemblies) to both propel the first aerial vehicle 102 in a first flight motion (e.g., forw ard flight) as well as a second flight motion, such as a hover position and / or multidimensional flight. In one example, the first aerial vehicle 102 may include one or more propeller assemblies 150 (e.g., multiple propeller assemblies). The propeller assemblies 150 may be coupled to booms (e.g., respective booms extending from wing assemblies 140) or otherwise configured to be positioned spaced apart from the fuselage 106. A rear or tail propeller assembly 152 may be coupled to the fuselage 106, such as to the tail 112. The tail propeller assembly 152 may propel the first aerial vehicle 102 in forward flight and / or hover or multidimensional flight. For example, the tail propeller assembly 152 may be articulable or movable based on the desired flight for the first aerial vehicle 102.

[0041] Other examples of the first aerial vehicle 102 may be found in International Patent Application No. PCT / US2024 / 014632, filed on February 28, 2024, and titled “Aerial Vehicle and Aerial Vehicle Systems,” the disclosure of which is hereby incorporated by reference in its entirety.

[0042] The second aerial vehicle 120 may be selectively attached to and / or stored within the first aerial vehicle 102 during flight to or from the delivery location. In such examples, the first aerial vehicle 102 provides propulsion for flights over a distance, such as from a pickup location to the delivery location. During such flight, the second aerial vehicle 120 may be attached to, partially inside, nested, or otherwise stored within the first aerial vehicle 102 in a retracted or stowed position. At a desired location, such as at the delivery location, the second aerial vehicle 120 may be deployed from the first aerial vehicle 102 to deliver a payload.

[0043] At the delivery location, the propulsion system of the first aerial vehicle 102 may enable hovering flight over the delivery' location at a first altitude or height above the delivery location (e.g., may include cruise and hover propellers). The second aerial vehicle 120 may be deployed from the first aerial vehicle 102 at the first altitude to the delivery' location. For example, the second aerial vehicle 120 may be released and allowed (e.g., using gravitational force) to descend downw ards from the first aerial vehicle 102. After delivery, the second aerial vehicle 120 may be retracted back into the first aerial vehicle 102. Both the descent and the ascent may be controlled by a retraction assembly (e.g., a tether 160) or another mechanism.

[0044] The second aerial vehicle 120 may nest in the vehicle compartment 124. The nesting may result in a more secure stowing of the second aerial vehicle 120. When the second aerial vehicle 120 is stowed in the first aerial vehicle 102, the bottom surface of the second aerial vehicle 120 may align with the bottom surface of the first aerial vehicle 102 to define a single bottom surface. When stowed, the second aerial vehicle 120 may provide additional stability or assist in balancing the first aerial vehicle 102 during forward flight. For example, the vehicle compartment 124 may be defined around a center of gravity of the first aerial vehicle 102. When stowed, a center of gravity of the second aerial vehicle 120 may be positioned to correspond with the center of gravity of the first aerial vehicle 102.

[0045] The second aerial vehicle 120 may include one or more propulsion assemblies 170 to maneuver the second aenal vehicle 120 relative to the first aerial vehicle 102. In one example, the propulsion assemblies 170 are arranged to provide forward and / or side-to-side movement of the second aerial vehicle 120, or rotation of the second aerial vehicle 120 about the tether 160.

[0046] Either or both of the first aerial vehicle 102 or the second aerial vehicle 120 may include one or more processing elements and / or sensors to load / deliver a package and / or to traverse a flight path from the pickup location to the delivery' location, to the pickup location or a service station, or to a designated or predetermined site. The first aerial vehicle 102 or the second aerial vehicle 120 may be autonomous, partially autonomous, or navigated by a user from a controlling location. The UAV 100 may operate in rural or urban locations. Accordingly, the first aerial vehicle 102 may deploy the second aerial vehicle 120 in a variety of locations and environmental conditions.

[0047] Either or both of the pickup location or the delivery location may be a warehouse, restaurant, retail store, service center, residential building or a similar location where delivery services may be utilized. A delivery recipient may designate the delivery location as a specific portion of a building or area, such as a door, a window, a deck, a roof, a parking area, or other locations accessible by a delivery recipient.

[0048] Other examples of the second aerial vehicle 120 may be found in International Patent Application No. PCT / US2024 / 018347, filed on March 4,2024, and titled “Autonomous Delivery Vehicle and System,” the disclosure of which is hereby incorporated by reference in its entirety.

[0049] FIG. 3 illustrates an example docking system 300 for one or more aerial vehicles (e.g., the UAV 100). The docking system 300 may include at least one dock 302, but may include more than one dock, such as docks 302 and 304 that mechanically retain UAVs 306 and 308, respectively (e.g., secure the UAVs in a docked configuration). In examples, the docks 302 and 304 may provide electrical connections (e.g., power and / or data) to the UAVs 306 and 308 to, for example, charge batteries of the UAVs 306 and 308 and / or provide mission information or other useful data to the UAVs 306 and 308. Each of UAV 306 and UAV 308 may be similar to the UAV 100, described above. To secure each UAV 306 or 308 to a dock 302 or 304, the docking assembly 130 of the first aerial vehicle 102 may be latched to the dock 302 or 304.

[0050] The docks 302 and 304 may be mounted on or otherwise held in place by a support 310. The support 310 may include a vertical tower 312 and arms 314 and 316. When held in place by the support 310, the docks 302 and 304 are generally positioned to receive UAVs 306 and 308. Although FIG. 3 is discussed with respect to two docks, in other instances, fewer (e.g., a single dock) or more than two docks may be coupled to the tower 312 or other support structure that supports the docks relative to the ground or other support surface and / or building.

[0051] In various examples, each dock 302 and 304 may be configured to charge a UAV and / or may be configured to allow a UAV to unload and / or receive pay load via a loading assembly 318. For example, dock 302 may be a charging dock, such that UAV 306 may receive electrical power (e.g., to charge batteries) via the dock 302. Dock 304 may be a loading dock, which may or may not provide charging capabilities to UAV 308. However, the dock 304 is generally placed relative to the loading assembly 318 such that the UAV 308 may utilize the loading assembly 318 to receive and / or deliver payload. For example, the second aerial vehicle 120 may descend from the first aerial vehicle 102 and pass through a chute 320 (or passage, tube, ramp, or guide rails) of the loading assembly 318 to deliver payload to, and / or receive payload from a loading station. The loading station may be located where convenient for user access, such as, without limitation, within the building adjacent to the docking system 300, outside the building (e.g., below a net or other barrier), etc. In examples, the docking system 300 may include a barrier 324. The barrier 324 may be a platform or net placed around an opening to the chute 320.

[0052] In various examples, docking assemblies may include different numbers of charging and / or loading docks, multiple towers, and the like. Other examples of the docking system 300 may be found in International Patent Application No. PCT / US2024 / 016087, filed on February 16, 2024, and titled “Docking Configurations for Aerial Vehicles,” the disclosure of which is hereby incorporated by reference in its entirety.

[0053] FIG. 4 illustrates the UAV 100 in a hover configuration. The propeller assemblies 150 may be configured for hover flight or multidimensional flight. For example, the propeller assemblies 150 may be oriented (e.g., angled generally downwards) to generate vertical lift or thrust, such as to allow the UAV 100 to hover in place. FIG. 4 illustrates the propeller assemblies 150 all in a same orientation / configuration (e.g., a clockwise configuration). In other examples, the propeller assemblies 150 may include other configurations. For example, the UAV 100 may include one or more propeller assemblies 150 in a first onentation / configuration (e.g., a clockwise configuration) and one or more propeller assemblies 150 in a second orientation / configuration (e.g., a counterclockwise configuration).

[0054] In examples, each propeller assembly 150 includes multiple blades 404 (e.g., a first blade 404A and a second blade 404B, more than two blades 404, etc., such that the propeller assembly 150 is a multi-blade propeller). The multiple blades 404 may provide the required lift for the UAV 100. In examples, the multiple blades 404 may be offset by an angle 410. For instance, the first blade 404A and second blade 404B may be offset by 60-degrees or approximately 60-degrees in the hover configuration. 60-degrees is one example, and the blades 404 may be offset by a different angle 410, including between about 30-degrees and about 90-degrees, between about 45-degrees and about 75-degrees, greater than 90-degrees, less than 30-degrees, etc. Each propeller assembly 150 may be configured similarly or include a different configuration. For example, a first pair of propeller assemblies 150 (e.g., a front pair) may be configured similarly, and a second pair of propeller assemblies 150 (e.g., a rear pair) may be configured similarly but different than the first pair of propeller assemblies.

[0055] FIG. 5 illustrates the UAV 100 in a forward flight or cruise configuration. In examples, the propeller assemblies 150 may move or orient to a position that facilitates forw ard flight. For instance, the multiple blades 404 of each propeller assembly 150 may fold or align during forward flight (e.g., along the direction of travel), such as to reduce drag and improve efficiency of the UAV 100. In such examples, the angle 410 between the first blade -11- 404A and the second blade 404B may be reduced or eliminated to align the blades 404 together. As detailed more fully below, the blades 404 may align automatically when the UAV 100 transitions to forward flight. For example, reducing the torque applied by the propeller assemblies 150 may cause the blades 404 to align. Conversely, the blades 404 may open to the hover position when spinning (e.g., as torque is applied to the blades 404). In examples, the blades 404 may open and close based on a combination of torque and thrust, such as a reduction of thrust (e.g., resulting from a reduction of applied motor torque) causing the blades 404 to align, and an increase of thrust (e.g., resulting from an increase of applied motor torque) causing the blades 404 to open. In examples, the blades 404 may be biased to their folded, cruise position, with the blades 404 moving to their unfolded, hover position when the propeller assemblies 150 are actuated.

[0056] FIGS. 6A-7B illustrate an example hub 602 for a propeller assembly 150 movable between a cruise configuration and a hover configuration. Referring to FIGS. 6A-6B, FIG. 6A illustrates the hub 602 or propeller assembly 150 in a first configuration, and FIG. 6B illustrates a partial cross-sectional view of the hub 602 or propeller assembly 150 in the first configuration and taken along line 6B-6B of FIG. 6A. The first configuration may include a first orientation of the second blade 404B relative to the first blade 404A. For example, the first configuration may be the folded, closed, or cruise configuration of the propeller assembly 150, such as with the first blade 404A and the second blade 404B aligned (e.g., the first orientation is parallel to the first blade 404A). The propeller assembly 150 or hub 602 may include a shaft 608. Referring to FIG. 6B, the shaft 608 may include a proximal portion 610 and a distal portion 612. A flange 614 may be defined on the exterior surface of the shaft 608 between the proximal portion 610 and the distal portion 612. In examples, the shaft 608 may be at least partially hollow, such as including an internal cavity 616 along a length of the shaft 608 to the distal end. In some examples, a spring 620 or other biasing element may be positioned within the internal cavity 616, such as to bias the blades 404 between configurations, as detailed below. One or more spring seats 622 may capture ends of the spring 620, such as to engage the spring 620 with the shaft 608, a blade, etc. The internal diameter of the shaft 608 may include an internal taper 630, such as to hold the spring 620 in position. For instance, a reduction in internal diameter of the shaft 608 may hold a top of the spring 620 in place, such as to provide a point or area against which the spring 620 may compress. In such examples, the spring 620 may be positioned within the internal cavity 616 to engage the internal taper 630 and the second blade 404B (e.g., a pin coupling the second blade 404B to the shaft 608).

[0057] The shaft 608 may be a motor shaft that rotates during operation of the propeller assembly 150, such as to rotate the first blade 404A and the second blade 404B. For example, a motor may rotate the proximal portion 610 to rotate the first blade 404A and the second blade 404B at the distal end. Along these lines, the first blade 404A may be coupled to the shaft 608 in a fixed orientation relative to the shaft 608. For example, the first blade 404A may be fixed to the distal end, such as at the terminal end of the shaft 608. As shown, the first blade 404A may be positioned around the distal end, and a primary retention used to secure the first blade 404A to the shaft 608, such as to prevent separation of the first blade 404A from the shaft 608. For instance, a first pin 636 may be inserted (e.g., press fit) through the first blade 404A and the shaft 608. A secondary retention, such as a first cotter pin 638, may be secured to the first pm 636 to limit pin removal. In examples, a tertiary retention may further retain the first blade 404A to the shaft 608. For instance, an optional nut 640 may be threaded to the distal end of the shaft 608 to secure the first blade 404A in place, such as to fix the first blade 404A in position, to secure the first blade 404A to a specific location on the shaft 608, or allowing motion of the first blade 404A relative to the shaft 608. Engagement of the nut 640 with the first blade 404A may limit or prevent rattle of the first blade 404A. For instance, the first blade 404A may rest or be pressed against the nut 640 to reduce vibration and / or limit an impact energy between the first pin 636 and the shaft 608. In examples, a first bushing 648 may be positioned between the first blade 404A and the shaft 608. The first bushing 648 may further limit rattle or slop between the first blade 404A and the shaft 608. In some examples, the first bushing 648 may include a first flange 650 between the first blade 404A and the second blade 404B. In such examples, the second blade 404B may be biased against the first flange 650 (e.g., via the spring 620), such as to transfer thrust or impact to the nut 640 and / or otherw ise reduce slop of the second blade 404B during flight.

[0058] The second blade 404B may be coupled to the slide along the shaft 608 and movable between a first configuration and a second configuration, such as to configure the propeller assembly 150 between the cruise configuration and the hover configuration. For example, the second blade 404B may be coupled to slide along the shaft 608 between the first blade 404A and the flange 614. As shown in FIGS. 6A-6B, the second blade 404B may be positioned adjacent the first blade 404A to define the cruise configuration. In examples, the second blade 404B may move both axially and rotationally relative to the first blade 404A when moving between the first configuration and the second configuration. For instance, when moving from the first configuration to the second configuration, the second blade 404B may move axially away from the first blade 404A and also rotate around the shaft 608, such as to define the offset angle 410 in the hover configuration.

[0059] Along these lines, a helix or track 658 (hereinafter “track” for sake of convenience without intent to limit) may be defined in or on the shaft 608. The track 658 may have a first portion and a second portion, such as a bottom 662 and a top 664. Although reference is made to “bottom” and “top,” such reference is by example only, and the two portions may be any separate location or portion of track 658. In examples, the track 658 may be defined by one or more grooves, slots, holes, surfaces, or formed features spiraling around the shaft 608, such as in a corkscrew shape (e.g., a helix shape). In other examples, the track 658 may include non-helix shapes. The track 658 may be defined as one or more apertures extending through the shaft wall, formed features within or on a surface of the shaft 608, or elements coupled to the shaft 608.

[0060] In examples, the shaft 608 may define an axis of rotation 670, such as along the longitudinal axis of the shaft 608. The bottom 662 of the track 658 may extend at an angle from the axis of rotation 670 along the shaft 608. For instance, the bottom 662 may extend between about 30-degrees and about 60-degrees (e.g., about 40-degrees) from vertical or from the axis of rotation 670, among other configurations. The top 664 of the track 658 may extend parallel to the axis of rotation 670, such as for purposes detailed below.

[0061] The second blade 404B may be positioned around the track 658, and a primary retention used to secure the second blade 404B to the shaft 608, such as to prevent separation of the second blade 404B from the shaft 608 while still allowing relative movement of the second blade 404B along the shaft 608. For instance, a second pm 674 may be inserted (e.g., press fit) through the second blade 404B and the shaft 608 to engage the track 658. A secondary retention, such as a second cotter pin 676, may be secured to the second pin 674 to limit pin removal. In examples, the second pin 674 may be sized to define a gap between the second pin 674 and the track or helix groove, such as to avoid direct forces on the second pm 674.

[0062] The second blade 404B may move relative to the first blade 404A via the track 658. For instance, the second pin 674 may engage the track 658 to move the second blade 404B between the first configuration and the second configuration with movement of the second blade 404B along the shaft 608. In examples, movement of the second pin 674 along the track 658 both rotates and adjusts the axial spacing of the second blade 404B relative to the first blade 404A. For instance, the second pm 674 may slide or traverse along or within the track 658 (e.g., between the first portion or bottom 662 and the second portion or top 664) to rotate -14- the second blade 404B around the axis of rotation 670 as the second blade 404B moves axially along the shaft 608 (e.g., along an axial length of the shaft 608). In examples, the second pin 674 may include multiple positions (e.g., a first position and a second position) relative to a length of the track 658. The blades 404 may be in different configurations for the multiple (e.g., two) positions of the second pin 674. For instance, the second blade 404B may be in the first configuration based on the first position of the second pin 674. Similarly, the second blade 404B may be in the second configuration based on the second position of the second pin 674. The different positions may be opposing positions along the length of the track 658 (e.g., top and bottom, left and right, up and down, in and out, etc.).

[0063] In the example shown in FIG. 6B, when the second pin 674 is positioned in the bottom 662 of the track 658, the second blade 404B may be positioned in the first configuration (e.g., to position the propeller assembly 150 in the cruise configuration). The spring 620 may be positioned within the shaft 608 to engage the second pin 674, such as to bias the second blade 404B towards the first blade 404A. For example, the spring 620 may bias the second pin 674 to the first position (e.g., to the bottom 662 of the track 658). In this manner, the second blade 404B may be biased to the first, cruise configuration, such as to snap or automatically move the blades 404 to the folded, cruise configuration when torque is reduced to the propeller assembly 150. The spring seat 622 engaging the second pin 674 may include a flat face, such as to allow rotation of the spring seat 622 relative to the second pin 674.

[0064] The track angle (e.g., helix angle) at the bottom 662 (and / or the spring pressure of the spring 620) may be chosen for a desired opening torque / speed or seating pressure against the first blade 404A. For example, the track or helix angle at the bottom 662 may be steep enough to drive the propeller assembly 150 shut, but also shallow allowing the blades 404 to open easily. In examples, the angle at the bottom 662 of the track 658 may allow around 70% of energy to be transferred into the first flange 650 of the first bushing 648 when shutting the blades 404. The angle may also result in greater spring force acting on the second blade 404B when closed, which may help keep the second blade 404B shut and from rattling while in the cruise configuration. The angle may also allow the second blade 404B to open at low speeds (e.g., at a low revolution per minute (RPM)) due to starting torque, facilitating the second blade 404B to move to a better performing position (e.g., for energy consumption and acoustics) sooner. For example, an initial starting torque may cause the propeller assembly 150 to open between about 75% and about 95% (e.g., about 90%) quickly (e.g., ahead of a full revolution), reducing energy consumption and acoustics. Thereafter, additional speed (e.g., to hover speed) will fully open the assembly.

[0065] In such examples, the blades 404 may be designed to take advantage of the quick acting track 658. For instance, each blade may include a high curvature airfoil, such as a high lift airfoil, that provides a high lift force (and resultantly a high drag) at low speeds. Such blade configurations may require motors with high torque output to overcome the increased drag at low speeds. As a result, the blades 404 may spin slowly while still providing necessary lift for the UAV 100. Such configurations may provide a desired energy consumption and acoustics for the UAV 100. For instance, high lift airfoils and the resulting low spin rate of the blades 404 may reduce the overall acoustic emissions of the propeller assembly 150, such as by reducing tip speed. In examples, the first blade 404A and the second blade 404B may be configured identically, or the second blade 404B may include a configuration different than the first blade 404A.

[0066] In examples, a second bushing 680 may be positioned between the second blade 404B and the shaft 608. The second bushing 680 may further limit rattle or slop between the second blade 404B and the shaft 608. In some examples, the second bushing 680 may include a second flange 682 between the second blade 404B and the flange 614. In such examples, the second flange 682 may be pressed against the flange 614 in the open, hover configuration, such as to reduce slop and / or transfer thrust or impact energy to the flange 614 and away from the second pin 674 during hover flight.

[0067] Referring to FIGS. 7A-7B, FIG. 7A illustrates the hub 602 or propeller assembly 150 in a second configuration, and FIG. 7B illustrates a partial cross-sectional view of the hub 602 or propeller assembly 150 in the second configuration and taken along line 7B-7B of FIG. 7A. The second configuration may include a second orientation of the second blade 404B relative to the first blade 404A. For example, the second configuration may be the unfolded, open, or hover configuration of the propeller assembly 150, such as with the second blade 404B rotationally offset from the first blade 404A (e.g., the second orientation is 60-degrees offset relative to the first blade 404A) and axially spaced from the first blade 404A. Referring to FIG. 7B, the second blade 404B may be positioned adjacent the flange 614 to define the hover configuration. For example, the second blade 404B (e.g., the second flange 682) may be pressed against the flange 614 for hover flight. In the example shown in FIG. 7B, when the second pin 674 is positioned in the top 664 of the track 658, the first blade 404A may be positioned in the second configuration (e.g., to position the propeller assembly 150 in the hover configuration).

[0068] The second pin 674 may slide along the track 658 to open the blades 404 as torque is applied to the propeller assembly 150. For example, torque applied to the shaft 608 (in addition to lift (e.g., a lift force) generated with rotation of the second blade 404B) may overcome the bias of the spring 620, compressing the spring 620 and causing the second blade 404B to move away from the first blade 404A and rotate around the shaft 608 as the second pin 674 slides along the track 658. In examples, as the second pin 674 moves within or along the track 658, the second pin 674 may move axially along the shaft 608 and, due to the curved features of the track 658, traverse along lateral sides of the shaft 608 (e.g., due to the second pin 674 being trapped within the walls of the track 658). In the second configuration, the second blade 404B may be axially spaced from the first blade 404A between about 15mm and about 45mm (e.g., about 30mm), although other configurations are contemplated. The axial or vertical spacing and offset angle of the second blade 404B from the first blade 404A in the second configuration may provide a desired acoustic performance, such as reducing the overall acoustic emissions from the propeller assembly 150 (e.g., providing a quiet configuration during hover flight). In examples, the axial / vertical spacing and offset angle may minimize influence from propeller downwash and wake. For instance, the lagging propeller may be positioned so as to not be in the wake or dow n w ash of the leading propeller.

[0069] The top 664 of the track 658 may be vertical (e.g., extending parallel or substantially parallel to the axis of rotation 670) to limit undesired shutting of the second blade 404B. For example, the track 658 may be vertical at the top 664 to limit the second blade 404B from shutting due to torque ripples or other anomalies, thereby keeping the second blade 404B locked open and limiting the second blade 404B from closing prematurely and / or unnecessarily, providing a range of compliance for the second blade 404B to remain in a fully open configuration. In some examples, the vertical section at the top 664 of the track 658 may direct all or substantially all impact energy into the flange 614 and away from the second pin 674. In this manner, the flange 614 may define a stop (e.g., a bump stop), such as to provide a stable platform to transfer force. The stop may limit a movement of the second pin 674 along the track 658, In some examples, the second pin 674 may be sized to define a gap between the second pin 674 and the top 664 of the track 658, such as to avoid direct forces on the second pin 674. The gap may be defined between the second pin 674 and the track 658 when the second bushing 680 is pressed against the flange 614.

[0070] The second blade 404B may snap or otherwise move back to the first configuration with a reduction of torque applied to the shaft 608. For example, reducing the hover thrust / torque below a threshold may cause the second pin 674 to leave the vertical section of the track 658. The threshold may be based on the bias (e.g., spring pressure) of the spring 620. For instance, below the threshold, the hover thrust may be insufficient to overcome the bias of the spring 620. In such examples, reducing the hover thrust / torque below the threshold will allow the spring 620 to move the second pin 674 down the track 658, such as dropping the second pin 674 out of the vertical section of the track 658. The threshold may be between about 40% and about 75% (e.g., about 60%) of hover thrust / torque, although other configurations and ranges are contemplated. A further reduction of hover thrust / torque may cause the second blade 404B to fold into the closed, cruise configuration, such as via the bias of the spring 620.

[0071] FIG. 8 illustrates an example installation strategy' for a fixed blade of a multi-blade propeller (e.g., the first blade 404A of propeller assembly 150). FIG. 8 illustrates the shaft 608, the first pin 636, and a first propeller hub 804 of the first blade 404A. Although not illustrated, the first bushing 648 may be positioned between the first propeller hub 804 and the shaft 608. In such examples, the first propeller hub 804 may include the first bushing 648. The first propeller hub 804 may be assembled onto the shaft 608. For example, the shaft 608 may be inserted into the first propeller hub 804, such as via an assembly jig. For instance, an assembly jig may assemble the first blade 404A in the correct orientation on the shaft 608. When the first blade 404A is properly positioned on the shaft 608, the first pin 636 may be installed. For instance, a pin pusher may be used to press fit the first pin 636 through the first propeller hub 804 and the shaft 608. As shown, the first pin 636 may extend across both the first propeller hub 804 and the shaft 608. When the first pin 636 is inserted, the first cotter pin 638 may be installed to retain the second pin 674. The nut 640 may also be secured to the shaft 608, such as torqued to a desired preload.

[0072] Various fits may be created between the components illustrated in FIG. 8. For example, a transition fit may be defined between the first pin 636 and the shaft 608, such as a transition fit hole of 4 + / - 0.02mm with the diameter of the first pin 636 of 4.004mm -4.012mm. An interference fit may be defined between one end of the first pin 636 and the shaft 608, such as an interference fit hole of 3.985mm - 3.965mm, A clearance fit may be defined between the other end of the first pin 636 and the shaft 608, such as a clearance fit hole of 4.3 + / - 0.05mm with the diameter of the first pin 636 of 4.004mm - 4.012mm. In examples, a gap may be defined between the first bushing 648 and the shaft 608. However, the gap may be limited to reduce slop and / or rattle between the first bushing 648 and the shaft 608. Such examples are illustrative only, and other configurations are contemplated.

[0073] FIG. 9 illustrates an example installation strategy' for a folding blade of a multiblade propeller (e.g., the second blade 404B of propeller assembly 150). FIG. 9 illustrates the shaft 608, the second pin 674, and a second propeller hub 904 of the second blade 404B. Although not illustrated, the second bushing 680 may be positioned between the second propeller hub 904 and the shaft 608. In such examples, the second propeller hub 904 may include the second bushing 680. The second propeller hub 904 may be assembled onto the shaft 608. For example, the shaft 608 may be inserted into the second propeller hub 904, such as via an assembly jig. For instance, an assembly jig may assemble the second blade 404B in the correct orientation on the shaft 608. In some examples, the assembly jig may position the spring 620 within the shaft 608. When the second blade 404B is properly positioned on the shaft 608, the second pin 674 may be installed. For instance, a pin pusher may be used to press fit the second pin 674 through the second propeller hub 904 and the shaft 608. In some examples, the assembly jig may hold the spring 620 as the second pin 674 is installed. As shown, the second pin 674 may extend across both the second propeller hub 904 and the shaft 608. When the second pin 674 is inserted, the second cotter pin 676 may be installed to retain the second pin 674.

[0074] Various fits may be created between the components illustrated in FIG. 9. For example, a clearance fit may be defined between the second pin 674 and the shaft 608, such as a clearance fit hole of 4.1 + / - 0.05mm with the diameter of the second pin 674 of 4.004mm - 4.012mm. An interference fit may be defined between one end of the second pin 674 and the shaft 608, such as an interference fit hole of 3.985mm - 3.965mm. A clearance fit may be defined between the other end of the second pin 674 and the shaft 608, such as a clearance fit hole of 4.3 + / - 0.05mm with the diameter of the second pin 674 of 4.004mm - 4.012mm. In examples, a gap may be defined between the second bushing 680 and the shaft 608. However, the gap may be limited to reduce slop and / or rattle between the second bushing 680 and the shaft 608. Such examples are illustrative only, and other configurations are contemplated.

[0075] The technology described herein may be implemented as logical operations and / or modules in one or more systems. The logical operations may be implemented as a sequence of processor implemented steps directed by software programs executing in one or more computer systems and as interconnected machine or circuit modules within one or more computer systems, or as a combination of both. Likewise, the descriptions of various component modules may be provided in terms of operations executed or effected by the modules. The resulting implementation is a matter of choice, dependent on the performance requirements of the underlying system implementing the described technology. Accordingly, the logical operations making up the embodiments of the technology described herein are referred to variously as operations, steps, objects, or modules. Furthermore, it should be understood that logical operations may be performed in any order, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

[0076] In some implementations, articles of manufacture are provided as computer program products that cause the instantiation of operations on a computer system to implement the procedural operations. One implementation of a computer program product provides a non-transitory computer program storage medium readable by a computer system and encoding a computer program. It should further be understood that the described technology may be employed in special purpose devices independent of a personal computer.

[0077] The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the invention as defined in the claims. Although various embodiments of the claimed invention have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, it is appreciated that numerous alterations to the disclosed embodiments without departing from the spirit or scope of the claimed invention may be possible. Other embodiments are therefore contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.

[0078] Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Further, the term “exemplary” does not mean that the described example is preferred or better than other examples.

[0079] The foregoing description, for purposes of explanation, uses specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will -20- be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Claims

1. A propeller assembly comprising:a shaft;a first blade coupled to the shaft in a fixed orientation relative to the shaft;a second blade coupled to move along the shaft and movable between a first configuration and a second configuration; anda pin coupling the second blade to the shaft, the pin engaging the shaft to move the second blade between the first configuration and the second configuration with movement of the second blade along the shaft.

2. The propeller assembly of claim 1, further comprising a track defined in the shaft, the pin moving within the track to move the second blade between the first configuration and the second configuration.

3. The propeller assembly of claim 2, wherein:the pin comprises a first position and a second position relative to a length of the track;the second blade is in the first configuration based on the first position of the pin; and the second blade is in the second configuration based on the second position of the pin.

4. The propeller assembly of claim 3, further comprising a spring to bias the pin to either the first position or the second position.

5. The propeller assembly of claim 3, wherein:the shaft defines an axis of rotation; anda first portion of the track extends parallel to the axis of rotation, the first portion associated with the first position of the pin.

6. The propeller assembly of claim 5, wherein a second portion of the track extends at an angle from the axis of rotation along the shaft, the second portion associated with the second position of the pin.

7. The propeller assembly of claim 6, wherein the angle is 40 degrees.

8. The propeller assembly of claim 1, wherein:the first configuration comprises a first orientation of the second blade relative to the first blade; andthe second configuration comprises a second orientation of the second blade relative to the first blade.

9. The propeller assembly of claim 8, wherein the first orientation is parallel to the first blade.

10. The propeller assembly of claim 8, wherein the second orientation is 60-degrees offset relative to the first blade.

11. The propeller assembly of claim 1, wherein the second blade moves between the first configuration and the second configuration based on a lift force generated with a rotation of the second blade.

12. A hub for a propeller assembly movable between a cruise configuration and a hover configuration, the hub comprising:a track having a first portion and a second portion; anda pin engaged with the track to slide along the track between the first portion and the second portion,wherein the pin is positioned in the first portion to position the propeller assembly in the cruise configuration, andwherein the pin is positioned in the second portion to position the propeller assembly in the hover configuration.

13. The hub of claim 12, further comprising a spring biasing the pin to the first portion.

14. The hub of claim 13, further comprising a shaft, wherein the spring is positionedwithin the shaft to engage the pin.

15. The hub of claim 12, further comprising a stop limiting a movement of the pin along the track.

16. The hub of claim 12, wherein a gap is defined between the pin and the track at each of the first portion and the second portion.

17. A propeller assembly comprising the hub of claim 12, the propeller assembly further comprising a shaft and a first blade coupled to the shaft via the pin, wherein movement of the pin along the track moves the propeller assembly between the cruise configuration and the hover configuration.

18. The propeller assembly of claim 17, further comprising a second blade coupled to the shaft via a second pin, wherein the second blade is fixed on the shaft, and wherein the first blade moves relative to the second blade via the track.

19. The propeller assembly of claim 18, wherein movement of the pin along the track both rotates and adjusts the axial spacing of the first blade relative to the second blade.

20. An unmanned aerial vehicle comprising the hub of claim 12.

21. A multi-blade propeller comprising:a shaft having an axial length;a first blade in a fixed orientation relative to the shaft;a second blade movable between a first orientation relative to the first blade, and a second orientation relative to the first blade;a track defined in the shaft;a first pin coupling the first blade to the shaft; anda second pin coupling the second blade to the shaft, the second pin engaging the track to move the second blade between the first orientation and the second orientation with movement of the second blade along the axial length.

22. The multi-blade propeller of claim 21, further comprising a nut threaded to the shaft and engaging the first blade.

23. The multi-blade propeller of claim 22, wherein the first blade is pressed against the nut to limit an impact energy transferred between the first pin and the shaft.

24. The multi-blade propeller of claim 21, further comprising:a first bushing positioned between the first blade and the shaft; and a second bushing positioned between the second blade and the shaft.

25. The multi-blade propeller of claim 24, further compnsing a flange defined on the shaft, wherein the second bushing presses against the flange when the second blade is in the second orientation.

26. The multi-blade propeller of claim 20, wherein a gap is defined between the second pin and the track when the second bushing is pressed against the flange.

27. The multi-blade propeller of claim 26, further compnsing a spring biasing the second pin to the first orientation.

28. The multi-blade propeller of claim 27, wherein the shaft comprises an internal cavity defined at least partially by an internal taper, and wherein the spring is positioned within the internal cavity to engage the internal taper and the second pin.

29. The multi-blade propeller of claim 21, wherein the first orientation defines a cruise configuration of the multi-blade propeller, and wherein the second orientation defines a hover configuration of the multi-blade propeller.

30. An unmanned aerial vehicle comprising the multi-blade propeller of claim 21.

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