Patent Publication Number: US-2021171199-A1

Title: Coupling Assembly for a Removable Propeller

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 16/412,775, filed May 15, 2019, which is a continuation of Ser. No. 15/197,596, filed Jun. 29, 2016, which claims the benefit of U.S. Provisional Patent Application No. 62/187,205, filed Jun. 30, 2015, the contents of which are incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure generally relates to the field of aerial vehicles and in particular to mechanical configurations for unmanned aerial vehicles. 
     BACKGROUND 
     Unmanned remote controlled aerial vehicles, such as quadcopters, continue to grow in popularity for both their commercial applications as well as recreational uses by hobbyists. 
     Another technology area with challenges has been power supply. Aerial vehicles are commonly powered by one or more batteries. After a battery loses its charge, a user may desire to swap out the battery, so that the aerial vehicle may continue to be flown without having to first recharge the battery. Consequently, a battery which can be removed quickly and easily is advantageous. Furthermore, some batteries swell or warp over time or when heated, which can make removal of a battery difficult. 
     As the popularity of aerial vehicles increases, an example area of technology that has been found susceptible to damage is assemblies for propeller blades. The propeller blades of an aerial vehicle may be susceptible to damage due to their light weight and high rate of rotation. Furthermore, due to their fragility, a user may wish to detach propellers prior to transporting the aerial vehicle. However, removing and attaching propeller blades may be time consuming or even impossible with existing aerial vehicles. Furthermore, many aerial vehicles require tools to remove propellers, which is inconvenient. Thus, it is advantageous to provide a propeller coupling assembly with easily replaceable propellers. 
     Additionally, during operation, processors, sensors, motors, and/or other electronics in aerial vehicles may overheat. Overheating may cause damage or cause electronics to behave sub-optimally. Aerial vehicles may need to carry heavy payloads or run computationally expensive image processing algorithms, exacerbating the overheating issue. Thus, a reliable means of cooling the aerial vehicle to offset the heat generated by the electronics may be advantageous. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed embodiments have advantages and features which will be more readily apparent from the detailed description, the appended claims, and the accompanying figures (or drawings). A brief introduction of the figures is below. 
         FIG. 1  is an example of a remote controlled aerial vehicle with an attached gimbal. 
         FIG. 2  illustrates an example configuration of a remote controlled aerial vehicle in communication with a remote controller. 
         FIG. 3A  and  FIG. 3B  illustrate an example of a pull-bar battery and a chassis of an aerial vehicle. 
         FIG. 4  illustrates an example of a pull-bar battery. 
         FIG. 5  illustrates an exploded view of a pull-bar battery and a chassis of an aerial vehicle. 
         FIG. 6A  and  FIG. 6B  illustrate an example of a removable battery and a chassis of an aerial vehicle with a lever assembly. 
         FIG. 7A and 7B  illustrate an example of a latch battery and a chassis of an aerial vehicle. 
         FIG. 8  illustrates an example of a propeller locking mechanism. 
         FIG. 9A  and  FIG. 9B  illustrate an example of a removable propeller. 
         FIG. 10  illustrates an example of a removable propeller coupled to a propeller locking mechanism. 
         FIG. 11  illustrates an example of vents and an air pathway to cool electronics in the aerial vehicle. 
         FIG. 12  illustrates an example of vents to cool electronics in the arm of the aerial vehicle. 
     
    
    
     DETAILED DESCRIPTION 
     The Figures (FIGS.) and the following description relate to preferred embodiments by way of illustration only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles of what is claimed. 
     Reference will now be made in detail to several embodiments, examples of which are illustrated in the accompanying figures. It is noted that wherever practicable similar or like reference numbers may be used in the figures and may indicate similar or like functionality. The figures depict embodiments of the disclosed system (or method) for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein. 
     Configuration Overview 
     Disclosed by way of example embodiments is a remote controlled unmanned aerial vehicle, or drone. 
     The aerial vehicle may include a removable battery. Various embodiments of removable battery assemblies may include a pull-bar battery assembly, a latch battery assembly, and a lever battery assembly. These various embodiments, may allow a user to attach and/or remove a battery quickly and easily. In some embodiments, the battery and/or the aerial vehicle include an element to assist a user in removing a battery that may have swollen or warped during operation of the aerial vehicle. 
     The aerial vehicle may include a propeller coupling assembly for coupling a propeller hub of a propeller to a propeller locking mechanism. The propeller locking mechanism may be rotated by a rotor of the aerial vehicle to rotate the propeller. The propeller locking mechanism may include a shaft, a plate, a spring, and one or more pins. The shaft may be coupled to a rotor. The plate may include an opening through which the shaft passes. The plate may have a toothed surface. The spring may encircle the shaft and may couple to the shaft and/or rotor at a first end and couple to the plate at a second end. The one or more pins may pins extend from the shaft. 
     The removable propeller may include a propeller hub coupled to one or more propeller blades. The propeller hub may include an aperture, one or more grooves, and one or more slots. The aperture may have a first opening at a first end of the propeller hub and a second opening at a second end of the propeller hub. The aperture may be cylindrical and the aperture may be coaxial with the shaft when the propeller locking mechanism couples to the propeller hub. The one or more grooves may each be formed in the aperture. Each groove may include a first opening at the first end of the propeller hub and a second opening at the second end of the propeller hub. The one or more grooves may be of sufficient size to allow the one or more pins of the propeller locking mechanism to pass through the grooves. The propeller hub may be a cylindrical shell, where the aperture is bounded by an internal surface of the cylindrical shell, and the one or more grooves are formed on the internal surface of the cylindrical shell. Each of the one or more grooves may rotate around an axis concentric with the aperture. The second opening of each of the one or more grooves may be directly opposite a respective one of the one or more slots. The one or more slots may be formed on the first end of the propeller hub. The propeller hub may also include a plurality of teeth extruding from the second end of the propeller hub. These teeth may reciprocally couple to the plate of the propeller locking mechanism. 
     When the propeller locking mechanism and the propeller hub are coupled together, each of the one or more pins of the propeller locking mechanism may fit into a corresponding slot of the one or more slots formed on the first end of the propeller hub, the aperture of the propeller hub may encircle the shaft, and the plate of the propeller locking mechanism and the second end of the second end of the propeller hub may mesh together. Also, the spring of the propeller locking mechanism may be compressed beyond its equilibrium when the propeller locking mechanism and the propeller hub are coupled together. 
     The aerial vehicle may also include vents in an arm of the aerial vehicle. The vents within the arm may capture airflow from around the aerial vehicle  100  and direct that airflow through one or more air pathways. The one or more air pathways may lead to components that benefit from cooling such as electrical motors, circuit boards and power sources. The cooling may allow for a decreased need in adding heat sinks to cool structures within the aerial vehicle. Moreover, this configuration also may help prolong operational use of the aerial vehicle  100  by obviating the need for additional weight from added heat sinks. 
     Example Aerial Vehicle Configuration 
       FIG. 1  illustrates an example embodiment in which the aerial vehicle  100  is a quadcopter (i.e., a helicopter with four rotors). The aerial vehicle  100  in this example may include a housing  130  for payload (e.g., electronics, storage media, and/or camera), one or more arms  135 , one or more rotors  140 , and one or more propellers  145 . Each arm  135  may mechanically couple with a rotor  140  to create a rotary assembly. Each rotor  140  may be coupled to a respective propeller  145 . When the rotors  140  are operational, all the propellers  145  may spin at appropriate speeds to allow the aerial vehicle  100  to lift (take off), land, hover, and move (forward, backward) in flight. Modulation of the power supplied to each of the rotors  140  may control the trajectory and torque on the aerial vehicle  100 . 
     A gimbal  110  may be coupled to the housing  130  of the aerial vehicle  100  through a removable coupling mechanism that mates with a reciprocal mechanism on the aerial vehicle  100  having mechanical and communicative capabilities. The gimbal  110  may be removed from the aerial vehicle  100 . In some embodiments, the gimbal  110  may also be capable of being removably attached to a variety of other mount platforms, such as a handheld grip, a vehicle, and a generic mount, which can itself be attached to a variety of platforms. In some embodiments, the gimbal  110  may be attached or removed from a platform without the use of tools. 
     The gimbal  110  may be a  3 -axis gimbal  110  with three motors, each corresponding to a respective axis. The gimbal  110  may be configured to allow for rotation of an object, such as a camera  120 , about an axis within an x-y-z Cartesian coordinate system. The gimbal  110  may couple to a camera frame  150  that couples to a camera  120 . The gimbal  110  and the camera frame  150  may form a mounting structure and when coupled together the entire assembly may be referenced as a gimbal  110  for ease of discussion. The camera frame  150  may be configured to allow the camera  120  to detachably couple (e.g., attach) to it and may include electrical connection points for the coupled camera  120 . The gimbal  110  may allow for the camera frame  150  to maintain a particular position and/or orientation so that the camera  120  mounted to it may remain steady as the aerial vehicle  100  is in flight. In some embodiments, the camera frame  150  may be integrated into the gimbal  110  as a camera mount. In some embodiments, the camera frame  150  may be omitted and the gimbal  110  may couple electronically and mechanically to the camera  120 . 
     Remote Controlled Aerial Vehicle 
       FIG. 2  illustrates an aerial vehicle  100 , which communicates with a remote controller  220  via a wireless network  225 . The aerial vehicle  100  in this example is shown with a housing  130  and arms  135  of an arm assembly. In addition, this example embodiment shows a rotor  140  coupled with the end of each arm  135  of the arm assembly, a gimbal  110 , and a camera  120 . 
     The aerial vehicle  100  communicates with the remote controller  220  through the wireless network  225 . The remote controller  220  may be a dedicated remote controller or may be another computing device such as a laptop, smartphone, or tablet that is configured to wirelessly communicate with and control the aerial vehicle  100 . In one embodiment, the wireless network  225  may be a long range wireless communication system, for example, a long range Wi-Fi system. It also may include or be another wireless communication system, for example, one based on long term evolution (LTE), 3G, 4G, or 5G mobile communication standards. The wireless network  225  may include a unidirectional RC channel used for communication of controls from the remote controller  220  to the aerial vehicle  100  and a separate unidirectional channel used for video downlink from the aerial vehicle  100  to the remote controller  220  (or to a video receiver where direct video connection may be desired). 
     The remote controller  220  in this example includes a first control panel  250  and a second control panel  255 , an ignition button  260 , a return button  265  and a screen  270 . The first control panel, e.g., control panel  250 , may be used to control the vertical direction (e.g. lift and landing) of the aerial vehicle  100 . The second control panel, e.g., control panel  255 , may be used to control the horizontal direction of the aerial vehicle  100 . Each control panel  250 ,  255  may be structurally configured as a joystick controller and/or touch pad controller. The ignition button  260  may be used to start the rotary assembly (e.g., start the propellers  145 ). The return button  265  can be used to override the controls of the remote controller  220  and transmit instructions to the aerial vehicle  100  to return to a predefined location. The ignition button  260  and the return button  265  can be mechanical and/or solid state press sensitive buttons. 
     In addition, the ignition button  260  and the return button  265  may be illuminated with one or more light emitting diodes (LED) to provide additional details. For example the LED may switch from one visual state to another to indicate with respect to the ignition button  260  whether the aerial vehicle  100  is ready to fly (e.g., lit green) or not (e.g., lit red) or whether the aerial vehicle  100  is now in an override mode on a return path (e.g., lit yellow) or not (e.g., lit red). It also is noted that the remote controller  220  may include other dedicated hardware buttons and switches and those buttons and switches may be solid state buttons and switches. For example, a button or switch may be configured to allow for triggering a signal to the aerial vehicle  100  to immediately execute a landing operation and/or a return to designated location. 
     The remote controller  220  may also include hardware buttons or other controls that control the gimbal  110 . The remote controller  220  may allow it&#39;s user to change the preferred orientation of the camera  120 . In some embodiments, the preferred orientation of the camera  120  may be set relative to the angle of the aerial vehicle  100 . In another embodiment, the preferred orientation of the camera  120  may be set relative to the ground. 
     The remote controller  220  also may include a screen  270  (or display) which provides for visual display. The screen  270  may be a touch sensitive screen. The screen  270  also may be, for example, a liquid crystal display (LCD), an LED display, an organic LED (OLED) display, and/or a plasma screen. The screen  270  may allow for display of information related to the remote controller  220 , such as menus for configuring the remote controller  220  or remotely configuring the aerial vehicle  100 . The screen  270  also may display images or video captured from the camera  120  coupled with the aerial vehicle  100 , wherein the images and video are transmitted to the remote controller  220  via the wireless network  225 . The video content displayed on the screen  270  may be a live feed of the video or a portion of the video captured by the camera  120 . It is noted that the video content may be displayed on the screen  270  within a short time (e.g., fractions of a second) of being captured by the camera  120 . 
     The video may be overlaid and/or augmented with other data from the aerial vehicle  100  such as the telemetric data from a telemetric subsystem of the aerial vehicle  100 . The telemetric subsystem may include navigational components, such as a gyroscope, an accelerometer, a compass, a global positioning system (GPS), and/or a barometric sensor. In one example embodiment, the aerial vehicle  100  may incorporate the telemetric data with video that is transmitted back to the remote controller  220  in real time. The received telemetric data may be extracted from the video data stream and incorporate into predefine templates for display with the video on the screen  270  of the remote controller  220 . The telemetric data also may be transmitted separate from the video from the aerial vehicle  100  to the remote controller  220 . Synchronization methods such as time and/or location information may be used to synchronize the telemetric data with the video at the remote controller  220 . This example configuration may allow a user, e.g., operator, of the remote controller  220  to see where the aerial vehicle  100  is flying along with corresponding telemetric data associated with the aerial vehicle  100  at that point in the flight. Further, if the user is not interested in telemetric data being displayed real-time, the data may still be received and later applied for playback with the templates applied to the video. 
     The predefine templates may correspond with “gauges” that provide a visual representation of speed, altitude, and charts, e.g., as a speedometer, altitude chart, and a terrain map. The populated templates, which may appear as gauges on the screen  270  of the remote controller  220 , may further be shared, e.g., via social media, and or saved for later retrieval and use. For example, a user may share a gauge with another user by selecting a gauge (or a set of gauges) for export. Export may be initiated by clicking the appropriate export button, or a drag and drop of the gauge(s). A file with a predefined extension may be created at the desired location. The gauge may be selected and be structured with a runtime version of the gauge. The gauge may also be played back through software that can read the file extension. 
     Removable Battery 
     In some embodiments, the aerial vehicle  100  contains one or more removable batteries. A removable battery, as used herein, may refer to both the electrochemical device used to store chemical energy in one or more cells and to the mechanical structure, e.g., the housing surrounding the electrochemical device and/or an assembly to mechanically couple to the aerial vehicle  100 . In some embodiments, the battery may be rechargeable. The housing may include electrical contacts, which allows the aerial vehicle  100  to receive power from the battery. The housing may also include electrical contacts which allow for charging the battery. In some embodiments, the contacts used to discharge the battery during operation of the aerial vehicle  100  may be the same contacts used to recharge the battery. The electrical contacts may also be used to communicate with the aerial vehicle  100 . This communication may allow the aerial vehicle  100  to receive an indication of the current charge of the battery or allow the aerial vehicle  100  to authenticate the battery via an authentication protocol. The housing of the battery may also contain mechanisms for mechanically coupling to the aerial vehicle  100  and/or mechanisms for assisting the user in attaching or detaching the battery to or from the aerial vehicle  100 . Herein, three types of removable batteries are illustrated: a pull-bar battery, a lever assembly battery, and a latch battery. 
       FIGS. 3A-3B  depict an example embodiment of a pull-bar battery  300  and the chassis  310 . The chassis  310  may be part of the aerial vehicle  100  and may provide a cavity within which the pull-bar battery mechanically couples. The pull-bar battery  300  may include a pull-bar  301  which may assist the user in removing the pull-bar battery  300 . The chassis  310  may be part of the housing  130  of the aerial vehicle  100 .  FIG. 3A  illustrates a right side view of the pull-bar battery  300  partially removed from the chassis  310  with the pull-bar  301  contracted. The arrow  320  in  FIG. 3A  illustrates the direction in which the user may push the pull-bar battery  300  when attaching the pull-bar battery  300  to the chassis  310 . In some example embodiments, the pull-bar  301  may be flush with the pull-bar battery  300  and/or the chassis  310  when contracted. 
       FIG. 3B  illustrates a rear, top, and right view of the pull-bar battery  300  coupled to the chassis  310  with the pull-bar  301  extended. The arrow  330  in  FIG. 3B  illustrates the direction that a user may pull on the pull-bar  301  to first extend the pull-bar  301  and then to remove the pull-bar battery  300  from the chassis  310 . In some embodiments, the pull-bar battery  300  may be removed (or decoupled) in one continuous motion simply by pulling on the pull-bar  301 . In some example embodiments, the pull-bar battery  300  couples to the chassis  310  by friction. In other example embodiments, when inserted completely into the chassis  310 , the pull-bar battery  300  may be locked into place by a latch or a set of latches on the chassis  310 . The latch or latches may couple to corresponding hardware on the pull-bar battery  300 . In some embodiments, the pull-bar battery  300  may include a latch which couples with a corresponding mechanism in the chassis  310 . One or more latches on the pull-bar battery  300  and/or on the aerial vehicle  100  may be disengaged by extending the pull-bar  301 , thus enabling the pull-bar battery  300  to be removed. It will be apparent to one skilled in the art that alternate locking mechanism may be used in place of a latch. The pull-bar  301  may function to unlock the pull-bar battery  300  from the chassis  310  as well as a handle to make removal of the pull-bar battery  300  easy for a user. The pull-bar  301  may make removable of the pull-bar battery  300  easier by operating as a handle for the user to grab when removing the battery. This may assist the user in removing a depleted or partially-depleted pull-bar battery  300  that would otherwise be difficult to remove in cases in which the pull-bar battery  300  has swelled or warped while being discharged. 
       FIG. 4  and  FIG. 5  illustrate a pull-bar battery  300  according to some example embodiments.  FIG. 4  illustrates a pull-bar battery  300  in isolation that includes the characteristic pull-bar  301 .  FIG. 5  illustrates an exploded view of the pull-bar battery  300 , partially inside the chassis  310  of the aerial vehicle  100 . In  FIG. 5 , the pull-bar  301 , a tab  500 , and a screw  501  are shown detached from the rest of the pull-bar battery  300  for illustrative purposes. The arrows  520  illustrate the way in which the pull-bar  301 , a tab  500 , and a screw may be assembled together. The arrow  530  illustrates how the pull-bar battery  300  may couple to the chassis  310 . Specifically, the pull-bar battery  300  may be inserted into the battery cavity formed by the chassis  310  to couple within the aerial vehicle  100 . In one example embodiment, the pull-bar  301  may be configured so that when it is pushed into the chassis  310  portion, a handle edge of the pull-bar battery  300  is substantially flush with a frame of the aerial vehicle  100 . 
     The chassis  310  may include a battery locking spring  540  which locks the pull-bar battery  300  in the chassis  310 . In some embodiments, when the pull-bar  301  is compressed, the battery locking spring  540  may prevent the pull-bar battery  300  from being removed. When the pull-bar  301  is compressed, a protruding element on the battery locking spring  540  may be adjacent to the tab  500  of the pull-bar battery  300 , thereby preventing the pull-bar battery  300  from being removed. That is, the contact between the tab  500  and the battery locking spring  540  may block the pull-bar battery  300  from being removed from the chassis  310 . When the pull-bar  301  is sufficiently extended away from the chassis  310 , the protruding element of the battery locking spring  540  may be pushed away from the tab  500  by a slanted surface on the pull-bar  301 , thus unlocking the pull-bar battery  300  from the chassis  310 . In this way, the pull-bar battery  300  may be locked into place by the battery locking spring  540  when the pull-bar  301  is compressed and may be unlocked (i.e., removable/decoupled) when the pull-bar  301  is extended. Similar locking mechanisms known to one skilled in the art which can be unlocked by extending the pull-bar  301  also may be used to couple the pull-bar battery  300  to the chassis  310 . 
       FIG. 6A  and  FIG. 6B  illustrate an example embodiment of a removable battery that that may be coupled and removed, by a lever assembly, from the battery cavity formed by the chassis coupled with the aerial vehicle  100 .  FIG. 6A  illustrates a right side view of a removable battery  600  and a chassis  310  with a lever  610 . The lever  610  is shown in an open position in  FIG. 6A . The removable battery  600  couples with the chassis  310 . 
     In order to couple the removable battery  600  with the chassis  310 , a user may push the removable battery  600  into a cavity of the chassis  310  in the direction indicated by arrow  620  and then pull the lever  610  towards the underside of the chassis  310  in the direction indicated by arrow  630 . In some embodiments, the lever  610  may operate a locking mechanism, which locks the removable battery  600  into the chassis  310  of the aerial vehicle  100 . This locking mechanism may be such that the removable battery  600  is locked into the chassis  310  when the lever  610  is closed and unlocked from the chassis  310  (i.e., able to be removed) when the lever  610  is open. In some example embodiments, pushing the removable battery  600  into the cavity in the chassis  310  may cause the lever  610  to be closed. Thus, only a single action may be required by the user to insert the removable battery  600  and lock it into place. In an alternate embodiment, the user inserting the removable battery  600  into the corresponding cavity in the chassis  310  may not close the lever  610 , and the lever  610  may need to be closed by a separate action of the user. 
       FIG. 6B  illustrates a rear, bottom, and left view of an embodiment of the removable battery  600  shown in  FIG. 6A  in which the lever  610  is nearly closed and where the removable battery  600  is fully inserted into the corresponding cavity in the chassis  310  of the aerial vehicle  100 . In order to remove (or decouple) the removable battery  600  from the chassis  310 , the lever  610  may be pulled away from underside of the chassis  310  in the direction indicated by the arrow  640 , which may unlock the removable battery  600  from the chassis  310 . The removable battery  600  may then be removed by pulling it the direction indicated by the second arrow  650 —down and away from a bottom of the chassis  310 . In some embodiments, pulling the lever  610  away from the underside of the chassis  310  when removing the removable battery  600  may also move the removable battery  600  in the direction indicated by the second arrow  650 . A user may subsequently remove the removable battery  600  by pulling in the direction of the second arrow  650  away from the chassis  310 . The mechanical advantage provided by the lever  610  may make removing the removable battery  600  significantly easier. This mechanical advantage may assist the user in removing a depleted or partially-depleted removable battery  600  that would otherwise be difficult to remove in cases in which the removable battery  600  has swelled or warped while being discharged. 
       FIG. 7A  and  FIG. 7B  illustrate an embodiment of a removable battery that may be coupled and removed from the aerial vehicle  100  by a latch or “squeeze open” assembly.  FIG. 7A  illustrates a left side view of the latch battery  700  and chassis  310 . In the embodiment illustrated in  FIG. 7A , the latch battery  700  is shown partially inside the corresponding cavity of the chassis  310 .  FIG. 7B  illustrates a rear, top, and right view of the chassis  310  and latch battery  700 . The chassis  310  may be part of the aerial vehicle  100 . The chassis  310  may have a cavity within with the latch battery  700  may be mechanically inserted and couple with the aerial vehicle  100  to provide power to the aerial vehicle  100 . 
     The latch battery  700  may include buttons  701  which may be used to decouple the latch battery  700  and the chassis  310 . The latch battery  700  may be coupled to the chassis  310  by pushing the latch battery  700  in the direction indicated by the arrow  710 . Once the latch battery  700 , is fully inserted into the cavity in the chassis  310 , a locking mechanism may be triggered. The latch battery  700  may be removed by pressing on the buttons  701  as depicted by the arrow  720  while simultaneously pulling the latch battery  700  in the direction indicated by the arrow  730 . 
     These various embodiments of batteries may allow a battery to be quickly attached to and/or removed from an aerial vehicle  100 . The various embodiments described above may also securely attach the battery to the aerial vehicle  100 . 
     Detachable Propeller 
     The propeller blades of an aerial vehicle  100 , such as a quadcopter, are often susceptible to damage due to their light weight and high rate of rotation. Thus, it may be advantageous to provide for easily replaceable propellers. 
       FIG. 8 ,  FIG. 9A ,  FIG. 9B , and  FIG. 10  illustrate example embodiments of removable propellers and corresponding propeller locking mechanisms which may allow for quick replacement of a propeller without the use of tools. A removable propeller and propeller locking mechanism may couple together as a propeller coupling assembly. The propeller coupling assembly may permit the propeller to be detached from and/or coupled to the aerial vehicle  100  without the use of tools. The propeller coupling assembly may lock the propeller into place and may be configured to prevent the propeller from accidently detaching from propeller locking mechanism. 
       FIG. 8  illustrates an embodiment of a propeller locking mechanism  800 . The propeller locking mechanism  800  may include a base  801 , a shaft  802 , a spring  803 , a one or more pins  804 , and/or a toothed plate  805 . The base  801  may be rigidly coupled to the shaft  802 , which may in turn be rigidly coupled to the one or more pins  804 . One end of the spring  803  may be attached to the base  801  and/or the shaft  802  and the other end may be attached to the toothed plate  805 . The base  801  may be rigidly coupled to the shaft  802  so as to comprise a single shaft. The toothed plate  805  may include a plurality of teeth that provide adjacent ridges and valleys to which a reciprocal element of a propeller  145  may couple. The teeth of the toothed plate  805  may be located on the side of the toothed plate  805  opposite the base  801  (i.e., the teeth may face away from the base  801 ). The shaft  802  may pass through the toothed plate  805  and the toothed plate  805  may be able to move up and down, along the axis of the shaft  802 . Vertical translation and/or rotation of the toothed plate  805  may cause the spring  803  to deform, e.g., compress, thus exerting an upward force on the toothed plate  805 . The shaft  802  and/or the base  801  may be coupled to a rotor (e.g., rotor  140 ) of the aerial vehicle  100 . The rotor  140  may rotate a propeller by rotating the shaft  802 . 
       FIG. 9A  and  FIG. 9B  illustrate example embodiments of a propeller  900 , which may couple to the propeller locking mechanism  800  illustrated in  FIG. 8 . The propeller  900  may be an embodiment of a propeller  145 . The propeller  900  may include a propeller hub  910  coupled to one or more propeller blades  930 . Only portions of the propeller blades  930  are shown in  FIGS. 9A and 9B , as illustrated by the broken lines. The propeller hub  910  may include one or more locking slots  940 , one or more grooves  920 , and one or more lead-in chamfers  960 . 
     The propeller hub  910  may include an aperture with a first opening at a first end (e.g., the top of the propeller hub  910 ) and a second opening at the second end (e.g., the bottom of the propeller hub  910 ). The first opening and the second opening may be connected by an internal surface. The internal surface may be an open cylinder in which the openings of the cylinder are the first and second openings of the propeller hub  910 . The one or more grooves  920  may be on the internal surface. The one or more grooves  920  may each include a first groove opening  922  at the first end of the propeller hub  910  and a second groove opening  924  at the second end of the propeller hub  910 . The first groove openings  922  of the one or more grooves  920  may be part of the first opening of the aperture of the propeller hub  910 . Similarly, the second groove openings  924  of the one or more grooves  920  may be part of the opening of the second opening of the aperture of the propeller hub  910 . In some example embodiments, a second groove opening  924  is formed in a lead-in chamfer  960  formed on the second end of the propeller hub  910 . The lead-in chamfer  960  may include two slanted edges that form an indent in the second end of the propeller hub  910 . The peak of the lead-in chamfer  960  may be co-located with the opening of the second opening  924  of a respective groove  920 . 
     The one or more locking slots  940  and the one or more grooves  920  may be formed as indents in the propeller hub  910  (e.g., on the first end of the propeller hub  910 ). In some example embodiments, the one or more locking slots  940  form a chamfered edge with the first end of the propeller hub  910  as illustrated in  FIG. 9A . The one or more grooves  920  may be on the interior of the propeller hub  910  (e.g., the grooves  920  may run along the internal surface of the propeller hub  910 ). In some example embodiments, the grooves  920  may rotate around an axis concentric with the internal surface of the propeller hub  910 , as illustrated in  FIG. 9A . In some embodiments, the grooves  920  may be parallel with the axis of the internal surface in the propeller hub  910 , as illustrated in  FIG. 9B . The propeller hub  910  may be in the shape of a cylindrical shell as illustrated in  FIGS. 9A and 9B . The propeller hub  910  may be rigidly attached to the one or more propeller blades  930 . The propeller hub  910  and the propeller blades  930  may be elements of the same material body. The propeller hub  910  may have a toothed bottom  950  that includes a plurality of teeth that provide adjacent ridges and valleys that may reciprocally couple to (and decouple from) the toothed plate  805  of the propeller locking mechanism  800 . 
     The propeller hub  910  may fit around the shaft  802  of the propeller locking mechanism  800 . In order to lock the propeller  900  to the propeller locking mechanism  800 , a user may place the propeller hub  910  of the propeller  900  over the shaft  802  so that the shaft  802  is aligned with the aperture of the propeller hub  910 . The pins  804  on the shaft  802  may block the propeller hub  910  from being pressed down unless the second groove openings  924  at the second end (e.g., the bottom) of the propeller hub  910  corresponding to the bottom ends of the grooves  920  are properly aligned with the pins  804 . The pins  804  may fit into the grooves  920 . By pressing down on the propeller  900  and rotating it, the propeller hub  910  may be moved past the pins  804  by running the pins  804  through the grooves  920  on the interior of the propeller hub  910 . In example embodiments in which the second groove openings  924  of the propeller hub  910  are formed in lead-in chamfers  960 , the lead-in chamfers  960  may make the user&#39;s task of aligning the second groove openings  924  with the pins  804  easier. 
     In some example embodiments, while the pins  804  enter the second openings  924  of the grooves  920  and/or enter the lead-in chamfer  960 , the toothed bottom  950  of the propeller hub  910  may come into contact with the toothed plate  805 . In alternate example embodiments, the toothed bottom  950  of the propeller hub  910  may come into contact with the toothed plate  805 , while the pins  804  are being passed through the grooves  920 . The toothed bottom  950  of the propeller hub  910  and the teeth on the top of the toothed plate  805  may reciprocally mesh together. As the propeller  900  is pressed down and rotated, the toothed plate  805  that is meshed to it may move down and rotate as well. Accordingly, as the propeller  900  is pushed down by the user, the spring  803  may cause the toothed plate  805  to exert a vertical restoring force on the propeller  900 . The teeth of the toothed plate  805  may mesh with those on the propeller hub  910  forming a Hirth joint. 
     Once the pins  804  have passed completely through the grooves  920  by passing through the first groove openings  922  of the grooves  920 , the user may maneuver the pins out of the grooves  920  so that the pins  804  are above the propeller  900 . The user may align the locking slots  940  on the propeller  900  with the pins  804 . The one or more locking slots  940  may have the same widths as the one or more grooves  920 , because the one or more locking slots  940  couple with the one or more pins which pass through the one or more grooves  920 . In some embodiments, torsion on the spring  803  may cause the locking slots  940  to align with the pins  804 , mitigating the need for the user to align the pins  804  and locking slots  940 . In some example embodiments, once the pins  804  have passed completely through the grooves  920  by passing through the first groove openings  922 , the spring  803  may exert a rotational restoring force on the propeller hub  910  causing the propeller hub  910  to rotate so that the pins  804  align with the locking slots  940 . In this way, the locking slots  940  of the propeller hub  910  may align with the pins  804  and the propeller hub  910  may lock into place when a user releases the propeller  900 . The vertical force exerted by the spring  803  may hold the propeller  900  in place by pushing the locking slots  940  into the pins  804 . Thus, when the pins  804  are in the locking slots  940  of the propeller  900 , the propeller  900  may be locked to the propeller locking mechanism  800 . 
     In some example embodiments, each of the pins  804  may be held at a first position by springs which are internal to the shaft  802  so that the pins  804  extend a first distance from the shaft  802 . When a force is applied to the pins  804 , such as when a user presses down on the pins  804 , the pins  804  may be pushed into the shaft  802  by compressing and/or extending the springs attached to the pins  804 . In some example embodiments, the groove  920  in the propeller  900  may be shallower at the top of the propeller  900  than at the bottom. 
     A groove  920  may be deep enough at the base of the propeller  900  so that a pin  804  can fit into the groove  920  without being pushed down, but may be too shallow at the top of the propeller for a pin  804  to fit into the groove without the pin  804  being pressed down. In such an embodiment, the user may not need to press down the pins  804  in order to attach the propeller  900  to the propeller locking mechanism  800 —the pins  804  may be pressed down as the propeller  900  is twisted onto the propeller locking mechanism  800  and the grooves  920  becomes gradually shallower. However, the pins  804  may need to be pressed down in order to remove the propeller  900 . This example embodiment may help prevent the propeller  900  from being inadvertently removed from the propeller locking mechanism  800  even if the pins  804  fall out of the locking slots  940 . In other example embodiments, the grooves  920  may be of uniform depth. In those example embodiments, the pins  804  may need to be pressed down in order to attach and to remove the propeller  900 . In some example embodiments the pins  804  are fixed (e.g., the pins  804  are not attached to springs and cannot be pushed down and thus the pins  804  extend a set length from the shaft  802 ). It is not required that the propeller locking mechanism  800  includes only two pins  804 —any number of pins  804  may be used. Also, the propeller locking mechanism  800  may include an element of any shape that extends from the shaft  802  in place of a pin  804 . Furthermore, in some example embodiments, the propeller  900  may include one or more pins on the internal surface of the cylindrical shell and the propeller locking mechanism  800  may include corresponding grooves on the shaft  802 . 
       FIG. 10  illustrates an example embodiment of a propeller coupling assembly including a propeller  900  locked into a propeller locking mechanism  800 . The embodiment shown in  FIG. 10  is similar to the embodiments shown in  FIG. 8 ,  FIG. 9A , and  FIG. 9B , in that attaching the propeller  900  to the propeller locking mechanism  800  may involve manipulating the propeller  900  so that the pins  804  pass through the grooves  920  of the propeller  900  and then rotating the propeller  900  so that pins  804  couple into the locking slots  940 . The spring  803  may push the propeller  900  upward so that it stays locked in place. In the embodiment illustrated in  FIG. 10 , the interconnecting teeth on the propeller hub  910  of the propeller  900  and the toothed plate  805  of the propeller locking mechanism  800  are different than those illustrated in  FIGS. 8, 9A, and 9B . The example embodiment of  FIG. 10  is illustrated with two teeth (only the first tooth can be seen in  FIG. 10 ), where each tooth is reciprocal with a respective lead-in chamfer  960  of the propeller hub  910 . It will be apparent to one skilled in the art that any number and/or manner of teeth or keying mechanisms may be used to connect the propeller hub  910  to the propeller locking mechanism  800  and to transfer torque from the propeller locking mechanism  800  to the propeller  900  during operation of the rotor  140 . The interconnecting teeth or keying mechanism may be such that when the propeller  900  is locked into the propeller locking mechanism  800 , the spring  803  exerts no torque on the propeller  900  (i.e., the deforming forces on the spring  803  exerted by the attachments of the spring  803  to the toothed plate  805  and the base  801  are purely compressive and produce no torque), when the rotor  140  is not in operation. In some embodiments, a sleeve coupling assembly, a key and keyset pair, a spline coupling assembly, and/or some other type of coupling assembly may be used in place of the toothed bottom  950  of the propeller hub  910  and the toothed plate  805 . 
     In some example embodiments, the toothed plate  805  may be held at an equilibrium position when the propeller  900  is not attached. During the process of attaching the propeller  900 , while the pins  804  are in the grooves  920 , the toothed plate  805  may come into contact with the toothed bottom  950  of the propeller hub  910 . The equilibrium position of the toothed plate  805  may be such that the rotation of the propeller  900  with the respect of the shaft  802  when this contact occurs will be the same relative rotation at which the propeller  900  is locked into the propeller locking mechanism  800 . For example, in the embodiment illustrated in  FIG. 9A , the bottom of each groove  920  is directly opposite a respective locking slots  940 . That is, the bottom of each groove  920  is directly under a respective locking slot  940 . Thus, if the spring  803  holds the toothed plate  805  at an equilibrium position so that the propeller  900  and the toothed plate  805  make contact when the pins  804  are near the bottom of the grooves  920 , then when the pins  804  are in the locking slots  940 , the propeller  900  will be at roughly the same orientation as when the toothed plate  805  first came into contact with the teeth of the propeller hub  910 . Because the spring  803  may be free of torsion when the toothed plate  805  is held at an equilibrium position, the spring  803  likewise may be free of torsion when the propeller  900  and the propeller locking mechanism  800  are locked together. Furthermore, because the position of the locking slots  940  correspond the position at which the spring  803  is free of torsion, the spring  803  may align the pins  804  and the locking slots  940  once the pins  804  have passed through the grooves  920 , which may make the action of locking the propeller  900  into place easier for a user. 
     The propeller coupling assembly allows the propeller  900  to removably couple to the propeller locking mechanism  800 . The propeller  900  may be quickly and easily attached to or removed from the aerial vehicle  100  without the use of the tools. The force of the toothed plate  805  on the propeller  900  resulting from the compressed spring  803  may keep the one or more pins  804  of the propeller locking mechanism  800  inside the locking slots  940  propeller hub  910 . The one or more pins  804  and/or the toothed plate  805  intermeshed with the toothed bottom  950  of propeller hub  910  may transfer a rotational load from the shaft  802  to the propeller  900 . 
     Thermal Vents 
       FIGS. 11 and 12  illustrate two example embodiments in which the arms  135  on the aerial vehicle  100  include vents. The vents may allow for airflow through the arms  135  for cooling of electronics within the aerial vehicle  100 . The electronics cooled by the airflow may be the motors that power the propellers, computer processors, and/or a power source for the aerial vehicle  100 ; e.g., battery or batteries. In some embodiments, the electronics may be near the airflow. In some example embodiments, the electronics may be connected to thermally conductive material, such as a metal wire, and the thermally conductive material may be convectively cooled by the airflow, which, in turn, cools the electronics. In some embodiments, the thermal vents may be coupled with, or integrated with, channels that direct received air to particular portions of the aerial vehicle  100 , e.g., where the electronics or power sources are located. 
     By way of example, in  FIGS. 11 and 12  the vents are on the top of the arm  135  underneath the propeller. When the propellers are active, this configuration may increase the airflow  1103  into the vents which may enhance the cooling. 
       FIG. 11  illustrates an example embodiment with one or more vents  1100 , an air pathway  1101  (or channel), and an outlet vent  1102 . The embodiment of  FIG. 11  may allow for airflow  1103  through the air pathway  1101 . The airflow  1103  is illustrated by a dashed-line indicating an air flow path within the air pathway  1101 . This airflow  1103  may be used to cool electronics in the arm  135  or in the housing  130  of the aerial vehicle  100 . Wires used to transfer power and/or control signals between the housing  130  and the motors in the rotors  140  may be in thermal contact with the airflow  1103 . This may allow heat generated by the motor to flow along the wire and be absorbed by the airflow  1103 , thus cooling the motor. The airflow  1103  also may be in thermal contact with electronics in the housing such as computer processors, sensors, communication circuits, and/or one or more battery. Thermal contact may comprise direct convective cooling of the electronics and/or convective cooling of a conductor that is in thermal contact with the electronics. 
     The airflow  1103  of each arm  135  may flow out of a single outlet vent  1102  or out of a plurality of outlet vents  1102 . The outlet vent  1102  is depicted in  FIG. 11  as being oriented upwards, but in alternate embodiments the outlet vent  1102  may be oriented in some other direction. It is noted that there may be one or more outlet vents  1102  and one or more outlet vents may be directed towards specific components in the housing for which cooling airflow may be desired. The air pathway  1101  may be a connected cavity in the arm  135  and the housing  130 , or may be a tube that runs from the vents  1100  to the outlet vent  1102 . In  FIG. 11 , three thin rectangular vents  1100  are depicted, but in alternate embodiments the vents  1100  may vary in number, size, shape, and position. 
       FIG. 12  illustrates an alternate example embodiment of vents which may allow for airflow through the arms  135  of the aerial vehicle  100 . The illustrated embodiment includes three vents  1200 , an air pathway  1201 , and an outlet vent  1202 , the combination of which may allow for airflow  1203  through the air pathway  1201 . The airflow  1103  is illustrated by three dashed lines which depict air flow paths. In  FIG. 12 , only one air pathway  1201  and outlet vent  1202  are illustrated, however it is understood the remaining two vents  1200  likewise may have corresponding air pathways and output vents. The airflow  1203  may cool electronics in the arm and/or electrical components in the rest of the aerial vehicle, if the electrical components are in thermal contact with the airflow  1203  (e.g., through a wire which is convectively cooled by the airflow  1203  and which is connected to the electrical component). Some example embodiments may include a single air pathway  1201  to which every vent  1200  and output vent  1202  is connected. In some example embodiments the arm  135  may be hollow, and the air pathway  1201  is the hollow cavity of the arm  135 . In some example embodiments, the arm  135  may include a different number of vents  1200  than is depicted in  FIG. 12 . 
     Vents in the arm  135  of an aerial vehicle  100  may provide a reliable means of cooling the aerial vehicle  100  to offset the heat generated by the electronics. Cooling the components of the aerial vehicle  100  may obviate the overheating of processors, sensors, motors, and/or other electronics in the aerial vehicle  100 . Placing the vents (e.g., vents  1100  or vents  1200 ) underneath a propeller  145  may produce greater airflow through air pathways (e.g., air pathway  1101  or air pathway  1201 ) resulting in active cooling of the aerial vehicle  100  without the need for additional fans and/or heat sinks. In this way, this configuration may help prolong operational use of the aerial vehicle  100  by obviating the need for additional weight from cooling components, such as heat sinks and/or cooling fans. 
     Additional Considerations 
     Throughout this specification, plural instances may implement components, operations, or structures described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. Structures and functionality presented as separate components in example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of the subject matter herein. 
     Unless specifically stated otherwise, discussions herein using words such as “processing,” “computing,” “calculating,” “determining,” “presenting,” “displaying,” or the like may refer to actions or processes of a machine (e.g., a computer) that manipulates or transforms data represented as physical (e.g., electronic, magnetic, or optical) quantities within one or more memories (e.g., volatile memory, non-volatile memory, or a combination thereof), registers, or other machine components that receive, store, transmit, or display information. 
     As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     Some embodiments may be described using the expression “coupled” and “connected” along with their derivatives. For example, some embodiments may be described using the term “coupled” to indicate that two or more elements are in direct physical or electrical contact. The term “coupled,” however, may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other. The embodiments are not limited in this context. 
     As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). 
     In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. 
     Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for the disclosed aerial vehicle and associated systems. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those skilled in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.