Abstract:
Generally, a mechanically self-regulating propeller is described which may have a central hub unit disposed around a shaft member, at least two blades coupled to the central hub unit, at least one timing hub coupled to each of the at least two blades, and a hydraulic unit coupled to the at least one timing hub. The at least one timing hub is slidably engaged to the shaft member. When not in use the blades lay substantially parallel to the central hub unit. When the central hub unit is rotated the blades begin to open or fan out to a position that is substantially perpendicular to the central hub unit. The propeller may be used any number of implementations including vehicles, generators, and any other mechanism requiring a propeller or similarly structured device.

Description:
CLAIM OF PRIORITY 
     This application claims priority to U.S. Application Ser. No. 62/155,891 filed on May 1, 2015, the contents of which are herein fully incorporated by reference in its entirety. 
    
    
     FIELD OF THE EMBODIMENTS 
     The field of the present invention and its embodiments relate to a collapsible propeller that can be used in a number of different situations to provide main and/or auxiliary power to a vehicle, namely an aircraft. In particular, the collapsible propeller has a series of pivotally linked blades that can lie substantially parallel with the axis of rotation or be positioned up to a substantially perpendicular position with regard to the axis of rotation. 
     BACKGROUND OF THE EMBODIMENTS 
     Collapsible propellers, impellers, and turbines have been designed for various implementations including but not limited to both manned and unmanned aerial vehicles, medical devices, windmills, boats, mechanical stirrers, and the like. The form of such collapsible structures are as varied as their intended usages. 
     Collapsible propellers can provide a number of benefits over traditional propellers, such as the ability to be selectively operated thus saving on energy and/or fuel costs, reducing drag (when not in use), and directionally control an aircraft without having to supply further moving parts. However, with such systems come a number of problems. 
     Since the propeller must move from a “closed” or non-use position to an “open” or use position, there can be a number of concerns regarding proper balance and removing vibrations from the system. Thus, the expansion between the closed and open positioned must be correctly regulated or timed so that each propeller blade changes position in a uniform fashion. Further, if the propeller opens or closes at speed, the blades may violently open and/or close thereby causing damage to the aircraft, the propeller itself, or potentially human lives. 
     Additionally, it would be desirable to have a propeller that could function in the above described manner without requiring undue manipulation and/or calculations from a pilot of the particular aircraft in question. This means such a system would regulate itself and prevent any type of human error which is often the source of many operation based failures of various apparatus and systems. 
     Thus, there is a need for an apparatus, such as a collapsible propeller, that can both open and close without under human manipulation. Further such a propeller must be safe to be selectively operated at speed without damaging any surrounding materials. The present invention and its embodiments meet and exceed these objectives. In addition, such a collapsible propeller can be applied to any situation or parent device other than aircrafts as previously described herein. 
     Review of Related Technology: 
     U.S. Pat. No. 6,371,726 pertains to a foldable propeller for a ship having a hub for mounting on a drive shaft of the ship, and at least two skew-type blades, each of which is pivotably arranged in the hub for configuration between a first, essentially folded together position and a second, essentially unfolded position, wherein each blade presents a generator line. Each of the blades has a skew distribution such that the leading edge of the inner and outer radii, respectively, are located substantially forward and aft of the generator line of the blade. The mid-chord line of the propeller extends substantially forward and aft of the generator line of the blade. A foldable propeller with such blade geometry provides improved performance; in particular, ready unfolding, high reverse thrust and low noise and vibration. 
     U.S. Pat. No. 4,624,624 pertains to a collapsible vertical wind mill, which comprises four main wings arranged in a rhombic form having a pair of opposed corners fitted on a shaft and auxiliary wings each provided on each of the main wings. The upper one of the pair corners on the shaft is fitted via a bearing capable of movement along the shaft. The other pair of opposed corners of the rhombic structure each have a hinged structure capable of variation of the angle. 
     U.S. Pat. No. 2,896,926 pertains to devices for mixing or treating fluids or free flowing powders. The invention comprises a rod or other support carrying a plurality of radial or diverging arms or blades hinged or jointed to the rod or support, or to a part carried thereby, and adapted to be folded towards or against the rod or support for the purpose of allowing the device to be passed through a restrictive aperture. 
     U.S. Pat. No. 2,198,475 pertains to a collapsible propeller for airplanes or for glider having auxiliary motors. The propeller comprises a rotary shaft, a plurality of blades, and a pivotal mounting for the blades upon the shaft permitting the arrangement of the same substantially parallel to the axis of rotation or at substantially right angles to said axis. 
     U.S. Pat. No. 1,496,723 pertains to an emergency propeller for use by aircraft that comprises two sections pivotally supported on the propeller shaft inward off the main propeller, said section being normally arranged in a line with the shaft and therefore in closed position, means being provided for solely holding the propeller blades and means being also provided for throwing and retaining the blades in the wind or water. 
     International Application WO2008/146947 pertains to a windmill that rotates a generator to generate electricity via wind power. The windmill has a hydraulic cylinder having a foldable propeller, a hydraulic cylinder for widening the propeller, a propeller shaft, a propeller shaft post, a bearing, a propeller shaft post angle adjusting bracket, and a propeller shaft post angle adjusting bracket shaft. 
     Various devices are known in the art. However, their structure and means of operation are substantially different from the present disclosure. The other inventions fail to solve all the problems taught by the present disclosure. The present invention and its embodiments provide for a mechanically timed collapsible propeller that can be selectively operated. Further, the propeller can be used to steer a craft, reduce drag, and operate under virtually any desired condition. At least one embodiment of this invention is presented in the drawings below and will be described in more detail herein. 
     SUMMARY OF THE EMBODIMENTS 
     Generally, the present invention and its embodiments provide for a collapsible propeller that can be implemented in a variety of fashions. For example, the collapsible propeller can be used to prime a turbine engine generator, by forcing air through an enclosed area, such as the engine&#39;s air intake, thus assisting in starting the actual rotary mechanism contained therein, and collapsing afterwards to reduce inlet drag, eliminating the need for starting mechanisms external from the engine assembly. In another instance, the collapsible propeller may be disposed on an aircraft for selective usage such as with human powered crafts or as an emergency backup in the event of the failure of the main propelling mechanism. 
     The collapsible propeller generally has a central hub that can be mounted in a number of fashions, and in a preferred embodiment, to the tail boom of an airframe. The central hub may also be mounted elsewhere such as in “tractor” or “pusher” configurations. Inside the hub, there are any number of bearings enabling rotation of the hub. Around the central hub, there are preferably between two and eight blades that are allowed to pivot or hinge approximately 90° between a “closed” or non-use position and an “open” or use position. The exact number and configuration of blades can depend on the required specifications and design requirements. 
     A timing hub may be positioned rearward, or behind, the central hub once assembled. The timing hub slidable engages the central hub and more than one timing hub may be used. If more than one is used, then one timing hub may be positioned behind the central hub and another in front of the central hub. The timing hub is coupled to each of the blades by timing arms and further coupled to one or more hydraulic cylinders. The hydraulic cylinders are also coupled to the central hub. 
     A drive motor, such as an electric motor, internal combustion motor, or the like, is coupled to the central hub via a drive sprocket or gearing set up. The position of this set up may vary and may depend on the type of motor in use. The motor provides the energy which turns the sprockets thereby rotating the central hub causing the blades to fan out in an open configuration. 
     In one embodiment there is a mechanically self-regulating propeller comprising a central hub unit disposed around a shaft member; at least two blades coupled to the central hub unit; at least one timing hub coupled to each of the at least two blades, wherein the at least one timing hub is slidably engaged to the shaft member; and a fluid buffer unit coupled to the at least one timing hub. 
     In another embodiment there is a mechanically self-regulating propeller comprising a central hub unit coupled to a shaft member such that rotation of the shaft member causes rotation of the central hub unit; a lock plate coupled to one surface of the central hub unit; a plurality of blades hingeably coupled to the central hub unit, wherein each of the plurality of blades comprise a blade body and a blade arm; at least one timing hub coupled to each of the plurality of blades, wherein the at least one timing hub is slidably engaged to the shaft member, and wherein each of the plurality of blades is coupled to the at least one timing hub via at least one timing arm; and at least one fluid buffer unit coupled to the at least one timing hub. 
     In yet another embodiment there is a mechanically self-regulating propeller comprising a central hub unit coupled to a shaft member such that rotation of the shaft member causes rotation of the central hub unit; a circular lock plate coupled to one surface of the central hub unit; a plurality of blades hingeably coupled to the central hub unit, wherein each of the plurality of blades comprise a blade body and a blade arm, and wherein the plurality of blades are capable of being positioned in at least an open and a closed position; at least one timing hub coupled to each of the plurality of blades, wherein the at least one timing hub is slidably engaged to the shaft member, and wherein each of the plurality of blades is coupled to the at least one timing hub via at least one timing arm; and at least one fluid buffer unit coupled to the at least one timing hub. 
     In some embodiments, the collapsible propeller is capable of being automatically deployed, that is, deployed in response to a push button, switch, knob, or the like or may be manually deployed using a lever or other comparable means to engage or disengage the blades of the propeller. 
     In general, the present invention succeeds in conferring the following, and others not mentioned, benefits and objectives. 
     It is an object of the present invention to provide a collapsible propeller that can be employed on a human powered vehicle. 
     It is an object of the present invention to provide a collapsible propeller that can be used on an unmanned vehicle. 
     It is an object of the present invention to provide a collapsible propeller that can be used to prime a generator or other mechanical equipment. 
     It is an object of the present invention to provide a collapsible propeller to alleviate balance and vibration during opening and closing of the propeller. 
     It is an object of the present invention to provide a collapsible propeller to decrease drag experienced by a parent system employing the propeller. 
     It is an object of the present invention to provide a collapsible propeller that can be used to steer a vehicle. 
     It is an object of the present invention to provide a collapsible propeller that can change the horizontal and/or vertical speed of a vehicle. 
     It is an object of the present invention to provide a collapsible propeller that can recharge a battery system coupled to the propeller. 
     It is an object of the present invention to provide a collapsible propeller that limits or prevents damage to the parent system. 
     It is an object of the present invention to provide a collapsible propeller that can be automatically and manually engaged. 
     It is an object of the present invention to provide a collapsible propeller that can operate as an air brake. 
     It is an object of the present invention to provide a collapsible propeller that can operate with other collapsible or non-collapsible propellers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of the present invention. 
         FIG. 2  is an exploded view of an embodiment of the present invention. 
         FIG. 3A  is a side view of an embodiment of the present invention in a closed position with a rear located timing hub. 
         FIG. 3B  is another side view of an embodiment of the present invention in an open position with a rear located timing hub. 
         FIG. 4A  is a side view of an embodiment of the present invention in a closed position with a forward located timing hub. 
         FIG. 4B  is another side view of an embodiment of the present invention in an open position with a forward located timing hub. 
         FIG. 5A  is a side view of an embodiment of the present invention in a closed position with a dual timing hub. 
         FIG. 5B  is another side view of an embodiment of the present invention in an open position with a dual timing hub. 
         FIG. 6A  is a side view of an embodiment of the present invention with an optional manual control mechanism coupled thereto. 
         FIG. 6B  is an enlarged side view of the optional manual control mechanism. 
         FIG. 7  is a side view of an aerial vehicle employing an embodiment of the present invention. 
         FIG. 8  is a top view of an aerial vehicle employing an embodiment of the present invention in a three propeller configuration, with two of the propellers in a closed position and one in an open position. 
         FIG. 9A  is a side view of an embodiment of the present invention in a closed position. 
         FIG. 9B  is a side view of an embodiment of the present invention in an open position. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention will now be described with reference to the drawings. Identical elements in the various figures are identified with the same reference numerals. 
     Reference will now be made in detail to each embodiment of the present invention. Such embodiments are provided by way of explanation of the present invention, which is not intended to be limited thereto. In fact, those of ordinary skill in the art may appreciate upon reading the present specification and viewing the present drawings that various modifications and variations can be made thereto. 
     Referring now to  FIG. 1 , there is a perspective view of the collapsible propeller  100 . The collapsible propeller  100  is preferably mounted upon a shaft member  104  on which it may rotate freely or once a mechanism is applied to cause rotation of the propeller. 
     Generally, the collapsible propeller  100  has a central hub unit  102 , blades  106 , a timing hub  108 , a lock plate  112 , at least one fluid buffer unit  110 , and a drive mechanism  124 . The blades  106  may comprise a blade body  107  and a blade body  109 . The timing hub  108  may have timing arms  114  that are coupled to the timing hub  108  and the blade arm  109 . The fluid buffer unit  110  may have a first arm  111  and a second arm  113 . 
     The central hub unit  102  is situated to be rotatably coupled to the shaft member  104 . The central hub unit  102  has bearings  118  (see  FIG. 2 ) which reside between the central hub unit  102  and the shaft member  104  to facilitate this rotative relationship. In at least one embodiment, the central hub unit  102  is designed to be mounted on a tail boom of an airframe. In other embodiments, the central hub unit  102  may be placed on supports or other structures capable of receiving the unit. On one face of the central hub unit  102 , there is a lock plate  112  coupled thereto. The lock plate  112  serves to limit the movement of the blades  106  when the collapsible propeller  100  is in motion. A length of the central hub unit  102  extends from this main section and terminates in a second “hub” where the fluid buffer unit(s)  110  are coupled thereto. 
     The central hub unit  102  further has at least two and preferably a plurality of receiving areas  103  (see  FIG. 2 ). The receiving areas  103  are sections of the central hub unit  102  designed and shaped to receive the blades  106 , namely the blade arms  109 , therein. A coupling mechanism  122  capable of permitting rotational movement, respective to the shaft member  104 , of the blades  106  is supplied to securely fasten the blades  106  to the central hub unit  102 . 
     The timing hub  108  is mounted to the rear or behind the central hub unit  102  as shown. However, other embodiments (including those described below) may have alternative configurations with respect to this relationship. The timing hub  108  is preferably slidably coupled to the central hub unit  102 . The timing hub  108  is coupled to each of the blades  106  via a timing arm  114 . At least one timing arm  114  couples the timing hub  108  to each of the blades  106  and in some embodiments, multiple timing arms  114  are used per blade  106 . 
     The timing hub  108  is further coupled to each of the at least one fluid buffer unit  110 . The fluid buffer unit  110  preferably comprises a first arm  111  and a second arm  113 . The second arm  113  is slidably engaged to the first arm  111 , allowing the second arm  113  to compress or slide into a recess in the first arm  111 . In some cases, the first arm  111  may be the sliding arm whereas the second arm  113  remains fixed and stationary. The fluid buffer unit(s)  110  preferably comprises a neutral hydraulic buffer cylinder that regulates the rate at which the timing hub  108  slides or moves along the central hub unit  102 . This primarily serves to prevent the blades  106  from contacting one another between a resting phase and an in-use phase of the collapsible propeller  100 . Not only does this prevent damage to the propeller itself but further limits potential damage to the apparatus to which the propeller is attached. 
     A drive mechanism  124  or drive sprocket may be coupled to the central hub unit  102  to provide power to the propeller from a power source such as a motor or other mechanical means. The drive mechanism  124  can be further located in a varying number of positions as needed. In some instances, multiple drive mechanisms  124  may be employed. 
     Referring now to  FIG. 2 , there is an exploded view of the collapsible propeller  100  demonstrating the interrelationship of the components of the propeller. Here, more of the physical structure of the collapsible propeller  100  is visible. 
     The timing hub  108  is shown as it would fit around the central hub unit  102 . The timing hub  108  may further have wings or protrusions for coupling the timing arms  114  to the blade arms  109 . Other suitable structures for the positioning and displacement of the timing arms  114  may also be used. The timing hub  108  is shown to be generally circular, however, other shapes may be applicable depending on the intended usage, shape of the shaft member  104 , or shape of the central hub unit  102 . 
     The central hub unit  102  may comprise at least a couple distinct areas and these areas may or may not be removable from one another. In some embodiments, the central hub unit  102  is a single piece to prevent breakage and reduce vibrations. The central hub unit  102  has a central hub  117  on one end and a backing  119  on the other end. Each may or may not be located on a physical end of the central hub unit  102  but simply reside at some point along the length of the central hub unit  102 . The backing  119  provides a surface for the fluid buffer unit  110  to be coupled opposite the timing hub  108 . 
     Further, the central hub  117  provides the surface and mechanisms for attachment or coupling of the blades  106  to the central hub unit  102 . The central hub  117  has receiving areas  103  which receive the blades arms  109  to be coupled therein by a coupling mechanism  122 . The number of receiving areas  103  may vary and may number between about two and about ten. 
     The bearings  118  are shown in their position between the shaft member  104  and the central hub unit  102 . The bearings  118  may be any suitable bearing and may vary in number between about one and about ten, with there being preferably three bearing disposed along the shaft member  104 . 
     The lock plate  112  rests against one surface of the central hub  117 . The lock plate  112  may have a particular shape to interact with the blade arms  109  thereby preventing rotation of the blades  106  past a certain angle. In some embodiments, there may be a lip of other structure on the blade arms  109  to facilitate this interaction. In some embodiments, the lock plate  112  is removable enabling different sized plates to be used with each having specific characteristics and interactions (i.e. permitted blade angle) with the blades  106 . The drive sprocket  124  is preferably disposed along the length of the shaft member  104 . 
     In  FIGS. 3A and 3B , there is a first embodiment of the present invention. Here, there is one timing hub  108  positioned behind the central hub  117 . The blades  106  are shown in a closed or in operative configuration ( FIG. 3A ) and an open or operative configuration in ( FIG. 3B ). Shown are the shaft member  104 , central hub unit  102 , blades  106 , fluid buffer unit  110 , lock plate  112 , timing arms  114 , bearings  118 , and drive mechanism  124 . In the closed configuration, the motor  116  (or other power source) is not operative and does not cause rotation of the shaft member  104  by way of the drive mechanism  124 . This position allows the collapsible propeller  100  to remain non-operative thereby saving on fuel and other energy expenditures when not needed, and further reducing drag when non-operational. 
     Preferably, once the motor  116  is engaged, the shaft member  104  begins to rotate causing rotation of the central hub unit  102 . As rotation and centrifugal force increase the non-fixed end of the blades  106  begin to move towards the position shown in  FIG. 3B . The movement of the blades  106  is controlled by the timing hub  108  and the fluid buffer units  110  which ensure proper control and a smooth transition between the closed and open positions. It is of note how the timing hub  108  moves along the central hub unit  102  and the blade arms  109  abut the lock plate  112  when in an open position. 
     In  FIGS. 4A and 4B , the timing hub  108  is located in front of the central hub unit  102 . In  FIG. 4A  there is a collapsible propeller  100  of this embodiment in a closed position and in  FIG. 4B  the collapsible propeller  100  of this embodiment is in an open position. Shown are the shaft member  104 , central hub unit  102 , blades  106 , blade body  107 , blade arms  109 , fluid buffer unit  110 , first arm  111 , second arm  113 , lock plate  112 , timing arms  114 , bearings  118 , drive mechanism  124 , and motor  116 . 
     In this embodiment, with the timing hub  108  located in front of the central hub unit  102 , in the closed position, the timing hub  108  rests against the face of the lock plate  112 . As power is applied, and the blades  106  open, the timing hub  108  moves forward down the shaft member  104 , away from the central hub unit  102 . In the fully open position, in some embodiments, the timing hub  108  contacts a stop plate, which may be part of the central hub unit  102 , to prevent additional forward movement of the blades and/or the timing hub  108 . Further, in this embodiment (as compared to the other embodiments described herein), the location of the fluid buffer units  110  must be changed, as shown, in order to connect the timing hub  108  to the central hub unit  102 . 
     Overall, this embodiment has the potential to support the widest, most aggressively angled blades  106 , as contact with the timing hub  108  and/or other components with the edge or face of the blades  106  is no longer an issue as with the other embodiments described herein. 
     In  FIGS. 5A and 5B , there is an embodiment that has two timing hubs  108  with one timing hub  108  located on each side of the blades  106  or central hub  117  along the central hub unit  102 . Shown are the shaft member  104 , central hub unit  102 , blades  106 , blade body  107 , blade arms  109 , fluid buffer unit  110 , first arm  111 , second arm  113 , lock plate  112 , timing arms  114 , bearings  118 , drive mechanism(s)  124 , and motor  116 . 
     With timing hubs  108  located both forward and rearward of the central hub  117 , in the closed position, one timing hub  108  is positioned away from the central hub  117 , while the other timing hub  108  rests against the face of the lock plate  112 . As power is applied, via the motor  116  or other mechanical means, and the blades  106  open, one timing hub  108  moves forward towards the central hub  117 , and the other timing hub  108  moves forward, away from the central hub unit  102 . In the fully open position, one timing hub  108  contacts the rear of the central hub  117 , and the other timing hub  108  contacts a stop plate, which may be part of the central hub unit  102 , located behind the drive mechanism  124 . Of the embodiments described herein, this particular embodiment may have the potential to support the largest size blades  106  since each blade  106  is timed from each side. 
     In  FIGS. 6A and 6B , there is yet another embodiment of the present invention. Shown are the shaft member  104 , central hub unit  102 , blades  106 , blade body  107 , blade arms  109 , fluid buffer unit  110 , first arm  111 , second arm  113 , lock plate  112 , timing arms  114 , bearings  118 , drive mechanism(s)  124 , control bar  120 , and motor  116 . Generally, the embodiment shown in  FIG. 6A , resembles the embodiment described in  FIGS. 5A-B . However, this particular embodiment further provides for a control bar  120  and at least one additional bearing  118  to selectively control the operation of the collapsible propeller  100 . 
     This mechanism of operation is highlighted in  FIG. 6B  which is enlarged portion of  FIG. 6A . Here, there is at least one additional bearing  118  is placed in a recess within the timing hub  108  positioned in front of the central hub  117 . Inside this bearing  118  rides an extension shaft  126 , to which a control bar  120  is mounted. This control bar  120  is preferably connected mechanically to a linear actuator, or other mechanical control component, which may draw the bar forward or in another suitable direction. As the control bar  120  moves from is position, the timing hub  108 , and subsequently, the blades  106 , are moved into the open position similar to that shown in  FIG. 5B . When the collapsible propeller  100  is manually moved into the open position, it may function as an air brake, which can be used, in some instances, to correct the course of the aircraft. 
     Furthermore, as the collapsible propeller  100  is moved into the open position, the force of oncoming air will cause the collapsible propeller  100  to rotate, in a process that is known as “wind milling.” This occurs because the collapsible propeller  100  is in an open position, however, it has not been engaged by a motor  116  or other mechanical means to cause rotation of the collapsible propeller  100 . Thus, in some instances an electric drive motor or motor  116  may be capable of acting as a generator. This “wind milling” propeller rotation can subsequently be converted into electric current and sent back through the electric power circuit to recharge the on-board batteries or other power storage device(s). This would, in turn, allow the propeller  100  to function as a “regenerative air-brake,” much like the regenerative braking systems becoming commonplace in electric/hybrid cars, such as the Toyota Prius or the Tesla Roadster. Essentially, when used in this configuration, any course correction in the flight plan could also be used to provide additional power, further increasing the range of the aircraft. 
     As described below, the concept of using the collapsible propeller  100  for course correction, may be achieved via this particular or other embodiments. In the embodiments where the timing hub  108  is located in front of the central hub  117 , the existing propeller could be modified with the control bar  120  and/or additional bearing  118  to provide the pilot or user with the option of mechanically controlling the opening and closing of the propeller blades, as shown and described. 
     In  FIGS. 7 and 8 , there is a glider  128  exhibiting at least one embodiment of the present invention. The glider  128  generally comprises a body  130 , wing(s)  134 , and a tail  132 . As shown, the glider  128  has multiple collapsible propellers  100  consistent with the present invention disposed thereon. Such a glider  128  may employ at least one collapsible propeller  100  and may have more than one collapsible propeller  100  with each collapsible propeller  100  being a particular size. In the configuration shown, there are two collapsible propellers  100  positioned on a propeller support  136 . The collapsible propellers  100  may, however, be mounted in any number of locations and configurations. A central collapsible propeller  100  is also located thereon. 
     As shown in  FIG. 7 , the central collapsible propeller  100  is in an open position and is larger than the two smaller collapsible propellers  100  in the propeller supports  136 . The two propellers on the supports  136  may be used to provide adequate thrust for taking off, whereas the larger collapsible propeller can be selectively opened once airborne, since the proper ground clearance may not be present when the craft is on the ground. Alternatively, all collapsible propellers  100  could be used simultaneously. The glider  128  shown is for exemplary purposes only and the exact specifications and configurations may deviate depending on the desired usage of embodiments of the present invention. Further explanation of uses of the propellers will be explained generally herein below. 
     Referring now to  FIGS. 9A and 9B , there is another embodiment of the present invention in a closed/open configuration, respectively. The blades and timing arms have been removed for clarity purposes only. 
     The main component of this propeller  100  is still the central hub unit  102 , composed of central hub  117  and lock plate  138 . This central hub unit  102  differs, however, from the other embodiments in that the bearings  118  it rides on are preferably installed into pockets or recesses milled directly into each end of the central hub  117 . The bearings  118  are then held in place within these individual bearing retaining plates. 
     This configuration may support a number of blades (not shown) located circularly around this central hub unit  102 . In a preferred embodiment, the blades may be spaced evenly at about 60 degree intervals. Each blade consists of at least a blade arm and blade surface. The blade arm runs nearly the length of the blade surface, and serves as a backbone or foundation, thereby increasing the structural integrity of each blade. Each blade is slid into an individual slot on the central hub  117 , from the front. As the blade is brought into position in the central hub unit  102 , it drops into a pocket. Halfway between the lower surface of this pocket and the outer surface of the central hub unit  102  itself, there is an additional slot, which may be cut perpendicular to the blade&#39;s length. This slot is intended to accept a blade mounting bolt, which runs through the pivot point of each blade. 
     Once the blades are installed in their individual slots on the central hub  117 , the central hub cover/lock plate  138  is installed over the top of the central hub  117 . This central hub cover  138  serves the purpose of keeping each blade mounted inside the central hub unit  102 , as well as limiting the forward movement of each blade as it transitions into the open position or configuration, serving as a “lock plate.” There may also be separate slots cut for each blade arm, each with several points of contact to evenly disperse the load generated by the forward movement and pressure of each blade as it enters the open position or configuration. 
     Once the central hub cover  138  and blades are installed in the central hub unit  102 , a second timing hub  108  is installed. This timing hub  108  rides on a timing hub travel tube  140 , which is secured to the front of the central hub unit  102 . Inside the timing hub travel tube  140 , there is an inner ring, which may be connected to the timing hub  108  via bolts or other appropriate securement mechanism, through slots cut into the surface of the timing hub travel tube  140 . Each slot terminates at the open position of the timing hub  108 , which may eliminate the need for a stop-plate or lock plate to limit any potential forward movement of the timing hub  108 , as the bolts will contact the end of each slot. 
     At a front face of this timing hub travel tube  140 , there may be a third bearing, which sits in a bearing retainer or recess which is bolted to the timing hub travel tube  140 . Aside from maintaining a linear path of motion for the timing hub  108  as it moves forward or rearward via the bolts positioned through the slots, the inner ring also serves as a mounting point for the hydraulic cylinders  110  (composed of  113  and  111 ), and control bars. 
     Each hydraulic cylinder  110  may also connected to the forward bearing retainer. Each control bar passes through the bearing retainer, where they are attached to a separate control plate  120 , which can be used to manually open the propeller blades without applying power 
     As the timing hub  108  is moved into the open position, each hydraulic cylinder  110  is compressed, and the control bars/plate  120  are allowed to extend through the forward bearing retainer, where they can be manipulated by an external mechanical control, should unpowered opening of the propeller be desired. Once the timing/control assembly is installed on the central hub unit  102 , each blade is then connected to the timing hub  108  via individual blade timing arms. These arms allow each blade to operate identically to all the other blades, maintaining smooth, uneventful opening or closing of the propeller  100 , with no risk of interference among blades. 
     A drive gear, may be further required for operation of the propeller  100 , which may be mounted to the forward area of the timing hub travel tube  140 , in front of the timing slots. Once power is supplied to the drive motor or engine is being used to power the propeller  100 , the entire propeller assembly will begin to rotate. 
     Initially, centrifugal force will cause each blade arm to slightly move away from its resting position, at which point each blade will begin to produce thrust. As the rotational speed increases, thrust also increases, which allows each blade to generate sufficient thrust to overcome the pressure exerted by the hydraulic cylinders  110 , at which point the timing hub  108  will move forward towards its open position. As the blades and timing hub  108  enter their open position, they will encounter both the lock plate  138  and the end of each timing hub tube slot, respectively. 
     The blades will remain in this position until power is removed from the propeller  100 , at which point they will return to their closed positions. While entering either the open or closed positions, their rate of position change will be controlled by the hydraulic buffer cylinders  110 , reducing the chance of damage caused by rapid opening or closing. If control bars are installed, they will also change position as well. Additionally, if control bars are installed, the propeller  100  can be forced into the open position manually, while the propeller is unpowered, similar in design to previous prototypes. If this occurs while the plane the propeller is installed on is moving forward, the propeller  100  will begin to “windmill,” while acting as an air-brake. This rotational movement can be used to spin an electric generator, effectively turning the propeller into a “regenerative air-brake.” 
     The collapsible propeller described in  FIGS. 1-8  is intended, in at least one embodiment, to be used selectively as needed in operation of a human powered or mechanically (engine) powered aerial vehicle, however, other applications are equally as applicable. For example, many of the larger turbine engines present on many commercial and military jets are primed via a smaller turbine. This “priming” turbine is typically mounted on wheels on the ground and is referred to as a “start cart” or air start unit (ASU). This unit provides high pressure air to assist in starting the turbine. These units are very heavy and thus relegated to ground use only, and cannot assist once the aircraft is airborne. 
     In some instances, a turbine can be shut down in flight after suffering a “flame out,” a loss of a sufficient fuel supply, or intentionally by the crew to save fuel. One proper methodology of restarting the turbine is to dive the aircraft using the airspeed of the craft to windmill the compressor and then supplying fuel and ignition to the turbine. However, the inclusion of an embodiment of the present invention into an air intake, may be able to be activated in such an event thereby priming the turbine without having to resort to diving the aircraft. Once the turbine has been primed by the present invention, the present invention is then collapsed and the aircraft continues on its travels. The lightweight and overall portability of the present invention enable this inflight usage over traditional ground priming methods employed today. 
     Alternatively, the present invention and its embodiments can also be used as the main propulsion system rather than an auxiliary priming system. While the collapsible propeller  100  is non-powered and the aircraft or aerial vehicle to which it is coupled is not airborne or otherwise being propelled, the collapsible propeller  100  can rest in the closed position, the open position, or in an alternative position therebetween, so long as the fluid buffer unit(s)  110  is neutrally charged (i.e. not pressurized to naturally move in one direction or the other). This is a preferred design variation, as the pressure of the fluid buffer unit  110  does not need to be overcome by the thrust generated by the collapsible propeller  100  while under power, or the drag created by the collapsible propeller  100  when not powered, in order to expand or collapse the blades  106 . 
     If the fluid buffer unit  110  is pressurized, the blades  106  can be kept closed while at rest, however, this force will need to be overcome by the thrust generated by the collapsible propeller when it is powered, slightly reducing overall system efficiency. While the collapsible propeller  100  is non-powered and the aircraft is airborne, the blades  106  are held in the closed position by the force of oncoming air, and/or the fluid buffer unit  110 , if it is indeed pressurized. 
     As power is applied to the collapsible propeller  100 , via human powered or other mechanical means, it will begin to rotate about the shaft member  104 . Initially, centrifugal force will cause the non-fixed end of each blade  106  to pivot or rotate away from its closed location, which may be substantially parallel to the shaft member  104 . At this point, each blade  106  will begin generating thrust to further move each blade  106  away from its closed location. As each blade  106  begins to pivot from its closed location, the timing hub  108 , coupled to the blades  106  via individual blade timing arms  114 , will begin to move forward (or backwards or both forwards and backwards depending on location and embodiment) towards the central hub  117 . 
     The timing hub  108  will keep the rate at which each blade  106  pivots uniform in relation to the others throughout its travel, preventing potential interference among the blades  106 , and limiting or eliminating any potential vibrational issues that may occur as a result of loss of balance by having one blade move at a different rate than the others. 
     As the timing hub  108  moves forward, it will apply force to the fluid buffer unit  110 . The fluid buffer unit(s)  110  will keep the rate at which the timing hub  108  moves along the central hub unit  102  controlled, subsequently allowing the blades  106  to pivot towards their open position in said controlled fashion, thereby reducing the chances of potential damage to the airframe or collapsible propeller  100  by having the blades  106  forced into their open position at a high rate of speed. So long as sufficient power is supplied to the collapsible propeller  100  to generate enough thrust to overcome the forces of drag due to oncoming air, and centrifugal force upon the propeller blades themselves, it will remain in the open position. 
     Once power to the collapsible propeller is reduced or removed, the force of drag due to oncoming air will begin to push the blades  106  rearward. Each blade  106  will begin to pivot at the point on the central hub  117  to which it is fixed. As each blade  106  pivots, it will apply force to the timing hub  108  via the individual blade timing arms  114 , and the timing hub  108  will begin to move rearward (or forwards or both depending on location and embodiment). Once again, the fluid buffer units  110  will control the rate of movement, to prevent damage to the collapsible propeller  100  or airframe by having the blades  106  enter their closed position at a high rate of speed. At this point, the collapsible propeller  100  will remain in the closed position, creating very little drag, until power is once again applied. Regardless of blade number, size, or timing hub position, the basic operating principles of the collapsible propeller  100  will not change. 
     While this collapsible propeller design is capable of being driven by any power source able to be translated into rotational force, it is preferentially suited for pairing with an electric motor, the power for which can be stored in on-board battery banks, or generated by an internal combustion engine to create a series electric hybrid style drive. Driving the collapsible propeller with an electric motor would enable rapid start/stop sequences or pulses, such that power is only consumed when thrust is needed and the collapsible propeller is engaged, thereby allowing the collapsible propeller to quickly return to the closed position, reducing drag as much as possible. 
     At least one applicable field of use that may benefit from this collapsible propeller is in the design and creation of unmanned aerial vehicles (UAVs). An exemplary design in this case would be a small, lightweight craft, which would be powered by at least one collapsible propeller. The UAV would take off and climb to a cruising altitude, where power would be removed from the collapsible propeller. The collapsible propeller would collapse into the closed position, thus eliminating as much drag as possible, and the UAV would glide until it falls to a lower altitude. The collapsible propeller would then be powered again, bringing the UAV up to the initial cruising altitude. This “rise and fall” cycle would be performed repeatedly, in order to maximize potential flight time of the craft in relation to available power supplies. To further increase the range of the UAV, the surface of the airfoil or wings of the craft may be covered with solar cells or other energy harvesting means, which would provide additional power to the on-board battery bank. 
     In some configurations, any number of collapsible propellers may be used. Thus, multiple collapsible propellers may be used on takeoff, and the UAV would follow the same “rise and fall” flight cycle as detailed above. In this case, however, corrections in flight course can be accomplished by providing power to the collapsible propeller opposite the path of correction, or, if the aircraft is currently engaged in ascent, by reducing or removing power to the collapsible propeller on the same side as the desired correction. This enables directional turning of UAV to the right by simply closing the right collapsible propeller and simply power the left collapsible propeller. However, in other instances, both collapsible propellers remain powered and one may simply reduce or remove power to the left or right or other collapsible propeller to provide for the proper course correction. 
     Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made only by way of illustration and that numerous changes in the details of construction and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.