Patent Publication Number: US-2022219820-A1

Title: Unmanned Flying Device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Application Ser. No. 62/077,783 filed on Nov. 10, 2014. The subject matter of said provisional application is incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed to unmanned flying devices, and in particular, to an unmanned flying device construction that provides for a collapsing or folding of the device&#39;s rotor blades upon a decrease or absence of rotor blade rotation about the device&#39;s body and for the deployment of the rotor blades away from the device&#39;s body upon a rotation thereof about the device&#39;s body. Such a construction, among other things, assists in preventing or minimizing damage to the device during a landing without the need for landing gear or other structure that may otherwise perform the function thereof. 
     Unmanned flying devices, also commonly referred to as “drones,” are well-known and becoming more popular. In all of the known examples, the rotor assemblies provide for the rotor blades to always be biased towards immediate deployment. For example, U.S. Publication No. 2009/0212157 describes the use of a torsion spring for biasing each blade away from their folded or retracted configuration. On the other hand, others have appeared to recognize that always maintaining the rotor blades in a deployed position is less than desirable for storage and/or during landing. For example, U.S. Pat. No. 8,469,307 describes blades that can fold upward or downward 90 degrees for storage or during a crash landing. However, as best understood, the device described in U.S. Pat. No. 8,469,307 still lends itself to damage and/or injury to persons. 
     It is thus believed that further advances to the state of the art are both desirable and achievable. In particular, it is desirable and achievable to provide an unmanned flying device that is compact, durable, and low cost to manufacture and in particular, provides for an improved blade and rotor arrangement in which the device&#39;s compactness and safety, and the minimization of damage to the device itself, is maximized through an improved blade collapsing assembly. 
     SUMMARY AND OBJECTIVES OF THE INVENTION 
     It is thus an objective of the present invention to overcome the perceived deficiencies in the prior art. 
     It is yet another objective of the present invention to provide an improved unmanned flying device construction that can be utilized for a variety of applications, including aerial surveillance, amusement (e.g. toy helicopters), and the delivery of items. 
     It is yet another objective of the present invention to provide an improved unmanned flying device construction that can overcome the bulky and awkward designs, fragile blades, and high cost of manufacture found in prior art devices. 
     It is yet another objective of the present invention to provide an improved unmanned flying device construction that is both convenient and practical to use, and that is also compact, durable and can be manufactured at a relatively low cost. 
     It is a further objective and feature of the present invention to provide an improved unmanned flying device that is easy to transport. 
     It is a further objective and feature of the present invention to provide an unmanned flying device that includes a symmetrical drone-like body. 
     It is a further objective and feature of the present invention to provide an unmanned flying device that includes blades which are biased towards folding to conform to the body of the unmanned flying device so as to minimize or prevent, among other things, damage to the device itself upon a landing or crash. 
     It is a further objective and feature of the present invention to provide such an unmanned flying device that includes blades that are spring loaded to automatically fold to conform to the body of the unmanned flying device. 
     It is a further objective and feature of the present invention to provide an unmanned flying device including at least one body and at least two foldable blades coupled to said body of the unmanned flying device, whereby rotation of said blades causes said blades to extend and deploy via centrifugal forces and aerodynamic lifting forces due to the rotation thereof, wherein said blades provide a propulsive lift when spun. 
     It is a further objective and feature of the present invention to provide an unmanned flying device that includes at least one collapsing element coupling said blades to said body of the unmanned flying device, said collapsing element biasing said blade to a folded position when not rotating. 
     Still a further objective of the present invention is to provide methodologies for carrying out and/or facilitating the foregoing. 
     Further objects and advantages of this invention will become more apparent from a consideration of the drawings and ensuing description. 
     The invention accordingly comprises the features of construction, combination of elements, arrangement of parts and sequence of steps which will be exemplified in the construction, illustration and description hereinafter set forth, and the scope of the invention will be indicated in the claims. 
     Therefore, to overcome the perceived deficiencies in the prior art and to achieve the objects and advantages set forth above and below, a preferred embodiment of the present invention is, generally speaking, directed to an unmanned flying device comprising a body; a first blade and at least a second blade; a coupling assembly for coupling the first blade and the at least second blade to the body, wherein the coupling assembly urges the collapsing of the first blade and the at least second blade towards the body; and wherein both the first blade and the at least second blade are rotateable about the body, and wherein the first blade and the at least second blade are deployable away from the body via rotation of the first and the at least second blades about the body. 
     In another preferred embodiment a method of landing an unmanned flying device is provided, wherein the device comprises a body, a first blade and at least a second blade, a coupling assembly for coupling the first blade and the at least second blade to the body, wherein the coupling assembly urges the collapsing of the first blade and the at least second blade towards the body, wherein both the first blade and the at least second blade are rotateable about the body, and wherein the first blade and the at least second blade are deployable away from the body via rotation of the first and the at least second blades about the body; and wherein the method comprises the steps of decreasing a rotational speed of the first blade and the at least second blade; and causing the first blade and the at least second blade to collapse toward the body; wherein the collapsing of the first blade and the at least second blade toward the body takes place prior to the landing of the device on a surface. 
     In a preferred embodiment, the unmanned flying device is what would commonly be referred to in the art as a “drone.” 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above set forth and other features of the invention are made more apparent in the ensuing Description of the Preferred Embodiments when read in conjunction with the attached Drawings, wherein: 
         FIG. 1  is an isometric view of an unmanned flying device constructed in accordance with a preferred embodiment of the present invention, illustrating its rotor blades in a “folded” or a “collapsed” position; 
         FIG. 1A  is a side view of the unmanned flying device illustrated in  FIG. 1 ; 
         FIG. 2  is an isometric view of the unmanned flying device illustrated in  FIGS. 1, 1A  illustrating its rotor blades in an extended or “deployed” position; 
         FIG. 3  is a cross-sectional view of the unmanned flying device illustrated in  FIGS. 1, 1A and 2 , wherein the rotor blades are illustrated in their extended or “deployed” position; 
         FIG. 4  illustrates features of an unmanned flying device constructed in accordance with a preferred embodiment of the present invention, in which the aerodynamic shells have been removed for ease of understanding; 
         FIG. 5  is an enlarged view of the top rotor of a preferred embodiment of the unmanned flying device of the present invention, illustrating torsion springs in the rotor arm hinges to help achieve the advantages and objectives as set forth herein; 
         FIG. 5A  is an enlarged view of the bottom rotor of a preferred embodiment of the unmanned flying device of the present invention, illustrating torsion springs in the rotor arm hinges to help achieve the advantages and objectives as set forth herein; 
         FIG. 5B  is an enlarged view of the bottom rotor of another preferred embodiment of the unmanned flying device of the present invention, illustrating a different coupling assembly that utilizes a single torsion spring in each rotor arm and which also helps achieve the advantages and objectives as set forth herein; and 
         FIG. 6  is a block and electrical wiring diagram for an unmanned flying device constructed in accordance with a preferred embodiment of the present invention. 
     
    
    
     Identical reference numerals in the figures are intended to indicate like parts, although not every feature in every figure may be called out with a reference numeral. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Generally speaking, the present invention is directed to embodiments of unmanned flying devices all having compact constructions capable of leveraging their overhead position or perspective to aid a user or group. The preferred embodiments of unmanned flying devices as set forth herein are preferably sized to be convenient for a single person to carry by hand or in a bag or case, but larger embodiments are contemplated depending on the desired application. 
     The preferred embodiments all preferably comprise a coaxial rotor design preferably comprising a pair of rotors aligned on a central axis. Embodiments including other rotor configurations including a quadcopter or multicopter configurations are also contemplated herein. Each rotor preferably comprises two or more aerodynamic blades, which provide propulsive lift when spun. While and when not spinning, these aerodynamic blades automatically fold, collapse or retract along the body of the unmanned flying device to, among other things, minimize or prevent damage to the device itself upon a landing or crash and make the device more convenient to pack and transport. The unmanned flying device can be remotely controlled by a user using communications such as radio control (R/C), Bluetooth, a tether or other appropriate means. The device could also operate autonomously, making and directing flight decisions with an onboard computer processor or microcontroller as well as the necessary supporting electrical sensors, motors, speed controllers and other components as would be understood in the art. 
     Reference is thus first made generally to  FIGS. 1, 1A, 2 and 3 , which illustrate an unmanned flying device, generally indicated at  10 , constructed in accordance with a first preferred embodiment of the present invention. 
     According to this preferred embodiment, unmanned flying device  10  comprises three (3) aerodynamics shells, generally indicated at  12 ,  14 ,  16 , which encase a central tube or shaft  25  about which the rotors, generally indicated at  32 ,  34 , of unmanned flying device  10  spin. Shaft  25  is preferably made out of a strong, stiff and lightweight material such as pultruded carbon fiber, plastic or aluminum and may be continuous or separated into pieces all as would be understood in the art. In this first preferred embodiment, central supporting shaft  25  is constructed from a pultruded carbon fiber tube approximately 10 inches long, 0.40 inches in outer diameter, and is preferably provided in two sections, which allows electrical wires to be routed inside thereof. Under appropriate circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances and the like, alternative embodiments are also contemplated where the central supporting shaft  25  might have a varying diameter or deviate from a circular cross-section and may span all or some of the unmanned flying device&#39;s length. 
     Mounted to shaft  25  are supporting members, bulkheads and brackets. The brackets, such as a support bracket  30 , allow for the attachment of motors, electronics, servo motors and other necessary components. These supporting members, bulkheads and brackets also provide a means to attach surrounding aerodynamic shells, such as  12  and  14  to a vehicle&#39;s central shaft  25 . Bulkheads  31  shown in  FIG. 3  are examples of supporting members in this embodiment used to couple aeroshell  14  to a central shaft  25 . 
     Preferably, these supporting members, bulkheads and brackets are constructed from plastic and fixed to the central shaft  25  by gluing, mechanical interference, friction fit or set screws, or other suitable methods. The brackets and bulkheads are sized to remain within the envelope of the surrounding aerodynamic shells  12 ,  14 , and in certain preferred embodiments, are sized just large enough to interface with them. In alternative preferred embodiments, the brackets and bulkheads may be sized to protrude past the aerodynamic shells. These bulkheads and brackets position and support the motor, servomotors, batteries and other mechanical and electrical components using screws, glue or other appropriate fastening methods. 
     Aerodynamic shells  12 ,  14  form an outer boundary, encasing and protecting the aircraft&#39;s internal components. Shells  12 ,  14  are sized so they do not negatively impact the air flow of the rotors while still being large enough to encase all or some of the unmanned flying device&#39;s internal components. Shells  12 ,  14  are preferably constructed from appropriately strong and stiff, lightweight materials such as plastics or composites. Depending on the circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances, or the like, shells  12 ,  14  may be provided into sections or made continuous and cover all or some of the unmanned flying device. Shells  12 ,  14  shroud the components below and between the rotors  32 ,  34 , while shell  16  shrouds the swashplate and bottom rotor  34 . Aerodynamic shell  16  is preferably coupled to the bearing of rotor  34  on the central shaft  25  and therefore spins with bottom rotor  34 . However, alternative embodiments are contemplated hereby. Preferably, shells  12 ,  14  attach to the central shaft  25  by means of mechanical interference with bulkheads and support brackets. 
     Generally speaking, device  10  comprises an upper rotor assembly and a lower assembly, each of the assemblies comprising among other things, a rotor, a rotor hub and a rotor bracket as will be discussed in greater detail below. The coupling of a rotor, rotor hub and rotor bracket, generally speaking, is well known in the art. Moreover, reference will be made herein to respective upper and lower rotor brackets. It should be understood that such rotor brackets may be a single unitary structure, or alternatively, may be individual bracket components or maybe coupled or otherwise connected together as would be understood in the art. That is, as will be understood herein, reference to the first and second rotor arms (or third and fourth rotor arms, as the case may be) being hingedly coupled to their respective rotor brackets should be understood that there may be a single upper (and lower, as the case may be) rotor bracket or the upper and lower rotor brackets, as the case may be, may be in components or sections, and therefore the claims should not be limited thereby. 
     Reference is now also made to  FIG. 4 , which illustrates each rotor  32 ,  34  being attached to the central shaft  25  via appropriately sized, radial, ball bearings, with thin bearings being the preferred, but not necessary choice. In the preferred embodiment, these bearings are embedded in rotor hubs  40 ,  45 . Rotor hubs  40 ,  45  are preferably constructed from plastic, but other strong, lightweight material may be appropriate depending on the circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances, and the like. Fixed to each rotor hub  40 ,  45 , preferably with screws, is a respective and preferred 1.5″ diameter, 72 tooth, nylon gear  50  which interfaces with an 8 tooth pinion of a respective electric motor, generally indicated at  100  (e.g.  FIGS. 3, 4, 6 ), which serves to spin respective rotors  32 ,  34 . 
     Under appropriate circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances, or the like, rotors  32 ,  34  could be spun using other elements and methods such as belts or magnets or with gears and pinions of a variety of diameters and tooth count, as would be understood by one skilled in the art. Additionally, gears made of other suitable materials including metals, resins, etc. may be employed under appropriate circumstances. Additionally, attachment of the rotor hubs  40 ,  45  to the central shaft  25  by any suitable alternate method that would allow low friction spinning and proper support may be employed, and such alternative embodiments are contemplated herein. These alternate embodiments could include thrust bearings, magnetic bearings and air bearings, for example and not limitation. 
     As illustrated in  FIGS. 3, 4  unmanned flying device  10  comprises four rotor blades, each of which are noted with reference number  60  and therefore can be referenced interchangeably or collectively as such, unless any specific rotor blade need be mentioned, and thus each rotor blade has been respectively referenced as  60 A,  60 B,  60 C,  60 D to avoid any confusion. Preferably, all of the blades  60  are constructed from carbon fiber, but other suitable strong and stiff materials with sufficient tensile strength could be used, including plastics, resins or other composites, or the like. 
     Each rotor blade  60  is coupled to its respective rotor and rotor hub by a respective coupling assembly having a rotor arm, generally indicated at  65 . That is, rotor blades  60 A,  60 B are coupled to rotor  32  and rotor hub  40  while rotor blades  60 C,  60 D are coupled to lower rotor  34  and rotor hub  45 . Each respective rotor arm  65  is preferably hingedly coupled to its respective rotor and rotor bracket by the use of hinges, generally indicated at  70 . 
     In a first discussed embodiment and with particular reference to  FIGS. 5, 5A , the coupling assembly may utilize a dual hinge configuration. Hereinafter, reference will be made to  FIG. 5B  in connection with an alternative preferred embodiment where the coupling assembly utilizes a single hinge configuration. Generally speaking, the use of hinges  70  and the disclosed rotor arms as configured herein allow each of the associated rotor blades  60  to be folded or retracted down along the outer aerodynamic shells  12 ,  14 ,  16  of the unmanned flying device  10  when the respective rotors  32 ,  34  are rotating sufficiently slow enough (as discussed below) and/or are not spinning. Among other things, this construction makes unmanned flying device  10  more convenient to pack and transport, and assists in protecting blades  60  while not in use, along with minimizing damage to the device  10  itself during landing or a crash. 
     For example, with reference to  FIGS. 5, 5A , the use of hinges  70 A,  70 B and rotor arm  65  with each rotor blade  60 , allows each of the associated rotor blades  60  to be folded or retracted down along the outer aerodynamic shells  12 ,  14 ,  16  of the unmanned flying device  10  when the respective rotors  32 ,  34  are rotating sufficiently slow and/or are not spinning. 
     In this first embodiment, each rotor arm  65  may be preferably comprised of two sections, namely rotor arm sections  65 A and  65 B, hingedly coupled together at hinge  70 A. Each rotor arm is preferably made of plastic, but other suitably strong and stiff materials could be used. As noted in  FIGS. 1, 1A , respective sections  65 B of each rotor arm  65 , when retracted, is preferably sized to fold and conform to the profile of the unmanned flying device  10 . In a particular embodiment, the blades are at least essentially parallel to the body of the device when in their collapsed position. While parallel might be preferred, at least essentially parallel is intended to mean within about 90% of parallel. 
     As shown in  FIG. 4 , each respective section  65 A of rotor arm  65  may likewise pivot upward (i.e. in connection with blades  60 C,  60 D) or downward (i.e. in connection with blades  60 A,  60 B) as the case may be, to permit the collapsing or folding of the blade  60  associated therewith. 
     A discussion of the coupling assembly and the construction of rotor arm  65  associated with blade  60 A (with the construction of rotor arm  65  associated with blade  60 B being of an identical construction) and the coupling assembly and the construction of rotor arm  65  associated with blade  60 C (with the construction of rotor arm  65  associated with blade  60 D being of an identical construction therewith) will now be made. 
     In connection with this two (2) hinged first embodiment, in each of the four (4) associated rotor arm/blade configurations, two (2) torsion springs are provided, which in a preferred embodiment, are wire torsion springs. For example, with reference to the rotor arm  65 /blade  60  configurations associated with blade  60 A in  FIG. 5 , a first torsion spring  80 B is provided at the hinge  70 B between rotor bracket  32 A and section  65 A of rotor arm  65 . A first end of spring  80 B is secured within a channel  81  in bracket  32 A while a second end of spring  80 B is in contact with a shoulder  82  of section  65 A. A second torsion spring  80 A is provided at the hinge  70 A between section  65 A and section  65 B of rotor arm  65 , and in a similar manner, a first end of spring  80 A is secured within a channel  83  in section  65 A while a second end of spring  80 A is in contact with a shoulder  84  of section  65 B. An identical construction is preferably used in connection with blade  60 B. Similarly, with reference to the rotor arm  65 /blade  60  configuration associated with blade  60 C in  FIG. 5A , a first torsion spring  80 B is provided at the hinge  70 B between rotor bracket  34 A and section  65 A of rotor arm  65  and a second torsion spring  80 A is provided at the hinge  70 A between section  65 A and section  65 B of rotor arm  65 . An identical construction is preferably used in connection with blade  60 D. Similar constructions at the hinge joints are used in connection with the rotor arms of these lower rotor blades  60 C,  6 D. That is, the ends of the respective springs associated with the rotor arm sections of each blade  60 C,  60 D are secured within respective channels in a similar manner as discussed above and disclosed with respect to  FIG. 5 . 
     The torsion provided by each of the respective springs  80 A,  80 B in  FIGS. 5, 5A  and the kinematics of the respective rotor arms and hinges force the associated rotor blades  60 A,  60 B,  60 C,  60 D to fold and retract along the profile of the body of unmanned flying device  10  when not experiencing external forces, as illustrated in  FIGS. 1, 1A . As illustrated in  FIG. 5 , the spring force of spring  80 B causes section  65 A of rotor arm  65  associated with blade  60 A to rotate downward until the lower surface  66  thereof is against surface  68  of rotor  32 . In this way, section  65 A is as compact as possible in the event of a landing, crash or during transport (see  FIG. 1 ). Section  65 A associated with blade  60 B likewise folds downward (see  FIG. 4 ). However, as the rotors  32 ,  34  spin, the centrifugal forces and the aerodynamic lifting force of the blades cause the blades  60  to deploy outwardly and into their extended positions (e.g.  FIG. 2 ) necessary to generate lift. However, if either rotor  32 ,  34  stops spinning (or is spinning slow enough) the centrifugal forces are once again lost (or sufficiently reduced) and the blades  60  associated with that stopped (or slowing) rotor collapse and fold back along the body. 
     Several references are made herein to the fact that blades  60  will be caused to fold downwardly upon the cessation of the (or the sufficiently slow) rotation thereof. That is, as would be understood by those skilled in the art, the threshold at which rotor blades  60  will automatically fold or collapse along the body of the device  10  does not require complete cessation of rotor rotation but will occur in accordance with the dynamics of the system and at a point in which the forces urging the full deployment (centrifugal and aerodynamic) thereof are overcome by the spring force of torsion springs  80 . That is, folding will occur when the RPM of the rotor decreases to a point at which the force moment (torque) about the rotor&#39;s respective hinges  70 A or  70 B induced by the centrifugal and aerodynamic forces acting on the rotating blades  60  are overcome by the torque induced on the hinges  70  by the torsion springs  80 . 
     Therefore, it should also be understood by those skilled in the art that rotor blades  60  will also automatically fold or collapse along the body of the device  10  when there is a lack of sufficient force urging the full deployment thereof. Sufficient force should be understood to mean the torque required about hinges  70 A or  70 B to overcome the closing torque induced by each hinge&#39;s respective torsion spring  80 . For example, experimental data has determined that if a blade with a mass of 15 grams and a center of gravity located 5 inches from the axis of rotation is rotating with an angular velocity of 750 RPM or greater, a 180 degree torsion spring with a torque value of 0.150 in-lbf when its legs are deflected 180 degrees, will be overcome and the blade will deploy, as would be understood in the art such that they may be slightly “coned” above perpendicular (by as much as 10 degrees). Also control inputs into the aft rotor may cause the blades to be slightly above or below perpendicular (tilting of the rotor plane), again this is about +/−10 to 15 degrees. In this way, aerodynamic lifting forces are generated necessary for flight. Those skilled in the art would easily be able to use such an exemplary embodiment to extrapolate such forces and rotational speeds to other sized blades and unmanned flying device constructions as set forth herein, generally. 
     It should be noted that alternative preferred rotor arm configurations and coupling assemblies are contemplated, which may utilize fewer (or which may require an increased number of) hinges  70  or rotor arm sections. 
     For example, reference is thus made to  FIG. 5B  for a disclosure of just such another preferred embodiment, wherein for simplicity and weight savings among other advantages, it may be advantageous to only have a single folding hinge  70  associated with each rotor arm  65 .  FIG. 5B  shows such an embodiment as implemented on a possible aft rotor  34  with its left side “L” showing a rotor blade  60  in the retracted position and the right side “R” showing a rotor blade  60  in its extended or deployed position. Some components are removed for clarity and ease of understanding. 
     That is, and similar in all other respects to the embodiments described above, each rotor blade  60  is coupled to its respective rotor and rotor hub by a respective rotor arm, generally indicated at  165 . Specifically,  FIG. 5B  illustrates each rotor arm  165  coupled to a respective rotor bracket  134 A with the use of a hinge  170 , which provides that each rotor arm  165  with each rotor blade  60  to be folded or retracted down along the outer aerodynamic shells  12 ,  14 ,  16  of the unmanned flying device  10  when the respective rotors  32 ,  34  are similarly not rotating fast enough or otherwise not spinning. Among other things, this alternative construction also makes unmanned flying device  10  convenient to pack and transport, and assists in protecting blades  60  while not in use, along with minimizing damage to the device  10  itself during landing or a crash. 
     Moreover, and again, similar to the embodiment described above, each rotor arm of this alternative embodiment is preferably made of plastic, but other suitably strong and stiff materials could be used and the coupling could be done with mechanical fasteners, press fit dowels, retaining pins or any other appropriately sized shaft or tube intended to act as an axle. With a single hinge embodiment as illustrated in  FIG. 5B , each rotor arm  165 , when retracted, is preferably sized to be low profile and conform to the outer mold line of the vehicle. 
     Each blade  60  is preferably attached to its respective arm  165  with a mechanical fastener, press fit dowels, retaining pins or any other appropriately sized shaft or tube intended to act as an axle. Other means could include adhesives, friction, “snap” fits or interference fits. Some embodiments will find it advantageous to have the blade  60  and associated arm  165  made as a single part that shares both their features. Such a blade that contained the features of the arm  165  could be made through injection molding of resins and plastics, carbon fiber layup or any other suitable method. 
     It should also be understood that the coupling assemblies that respectively couple blades  60 A,  60 B to the upper rotor  32  (e.g. rotor bracket  32 ) could likewise include only one hinge each. That is, instead of the upper coupling assemblies that utilize the dual hinge construction of  FIG. 5A , blades  60 A,  60 B could instead also utilize a single hinge assembly as set forth in  FIG. 5B . 
     In all other respects, the single hinge construction for each of the coupling assemblies for blades  60 A,  60 B,  60 C and  60 D is preferably identical to the double hinge construction as set forth above. 
     It should also be noted that for designs not using the coaxial configuration, the arms and blades of each rotor could fold and conform along any convenient surface, which would enhance the ability for the unmanned flying device to be transported and handled while not in operation. 
     It should be further noted that other suitable methods and means of construction of inducing the folding motion of the blades  60  could be employed in alternative embodiments, such as using elastics, linear springs, magnets and/or a combination thereof, and such means of construction, alone or in combination, could be further used in lieu of or in combination with the disclosed torsion springs, as long as the retracting force of the spring, elastic, magnet or other device(s) can be overcome by the centrifugal forces generated by the spinning rotor blades  60  and it can be ensured that the blades  60  remain fully extended during flight, or at least until the design parameters are such that retraction or folding is desired (e.g. upon very close to landing and/or crashing, as the case may be). 
     Advantageously, rotor blades  60  that automatically fold or collapse along the body of the device  10  as disclosed herein allows, provides and/or otherwise permits embodiments hereof to omit landing gear configurations, legs or supports, which might otherwise adversely affect the advantageous compact design and low cost of manufacturing of the present invention. That is, because the rotor blades  60  retract or collapse as disclosed herein, such blades need not be otherwise protected during landing or crashing to prevent damage thereto. Such a construction, among other things, provides for improved safety while using the devices as set forth herein, improved minimization of damage to the device itself, and a significant savings in manufacturing costs, weight and size, among other things, because structure to assist in landing is not necessary. That is, because unmanned flying device  10  can halt its rotors prior to landing, the loss of centrifugal force would result in the blades retracting and folding prior to the crash or landing, thereby protecting them during a belly or otherwise “hard” landing. 
     Reference is again made to  FIGS. 4 and 5A  for a discussion of providing a controlled flight, which is achieved by changing the relative pitch or “feather” of the bottom rotor blades  60 C,  60 D (cyclic pitch), although noting again for the avoidance of doubt that the single hinge configuration operates at least similarly, if not identically thereto. This change in relative pitch is achieved with linkages, generally indicated at  67 , which connect the bottom rotor  34  to a swashplate, generally indicated at  72 . The swashplate  72  is in turn connected via linkages to a pair of servo motors  55  which can change the angle of the swashplate  72 . As is understood by those skilled in the art, the bottom rotor bracket  34 A pitches or “feathers” on internal radial bearings in response to the induced angle of the swashplate as it rotates about the central shaft  25 . In a preferred embodiment, the swashplate  72  is constructed from plastic and contains an internal, radial ball bearing which pivots on a plastic spherical bearing. The linkages  67  are preferably made from stainless steel or plastic and connect to the servo horns  56  and swashplate  72  with snap together, plastic ball-and-socket joints or traditional hinges. However, under appropriate circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances, or the like, other methods of connecting linkages could be employed, such as universal joints or hinges. Preferably, the material of any such linkages and swashplate as contemplated herein is lightweight, stiff and of an appropriately strong material, as would be understood in the art. 
     According to further alternative embodiments, it may be advantageous to use cyclic pitch control applied to both the top and bottom rotors  32 ,  34  or have a mechanism for collective pitch control of the rotors  32 ,  34  or utilize three or more servo motors to control the pitch applied to the swashplate or achieve directional control by shifting the center of gravity of unmanned flying device  10 , depending on the circumstances and as would be understood in the art. 
     Reference is now also made to  FIG. 6 , which illustrates an electrical wiring and block diagram for unmanned flying device  10 , constructed in accordance with a preferred embodiment of the present invention, and which is applicable to all constructions and embodiments disclosed herein. 
     Preferably, unmanned flying device  10  comprises and is powered by two (2) 1.1 inch diameter, 7.4V, brushless, electric motors, each generally indicated at  100 , wherein a respective one of the motors  100  drives rotor  32  while the other motor  100  drives rotor  34 . Motors  100 ,  100  are preferably located between the top and bottom rotors, as illustrated in  FIG. 3  and are preferably mounted with screws to plastic brackets on the central shaft  25 . Each electric motor  100 ,  100  is preferably controlled by a respective one 20 amp, electronic speed controller (ESC)  110  positioned in close proximity to its respective motor  100 . The two motors  100 ,  100  and two controller  110  are preferably powered by a pair of 1300 mAh, 2 cell, Lithium Polymer (LiPo) batteries  120 ,  120  located beneath the bottom rotor. Preferably, the LiPo batteries  120 ,  120  are secured in place with cutouts in bulkheads. Preferably as well, the electrical wires (not shown) are routed up the central shaft  25  to connect the batteries, and control wires from the controllers  110 ,  110  are routed down the central shaft  25  to a microcontroller/microprocessor  130 . 
     Microcontroller or microprocessor  130  may also be provided with appropriate power regulators. Additionally, microelectromechanical sensors, which may include by example and not limitation, gyroscopes, accelerometers and magnometers, may be provided and indicated generally at  140 . In addition, an electrical barometer and/or a Global Positioning System (GPS) receiver may be provided, which is also generally indicated at  150 . The microcontroller  130  preferably uses one or more of the microelectromechanical sensors  140  to predict the orientation of the unmanned flying device during flight. The microcontroller  130  may then use this prediction to apply control signals to the servomotor  55 , which may modify the angle of the swashplate  72  producing rotation of unmanned flying device  10  due to the change in relative pitch of the lower rotor blades  60 C,  60 D. The microcontroller or microprocessor  130  can use this control to fly autonomous missions or to enhance stability while a user is controlling it via a wire or wireless remote. Additionally, the GPS receiver and/or barometer, if provided, can provide information about the position of unmanned flying device  10  relative to the earth, which the microcontroller  130  can then use to fly to particular locations or maintain a particular altitude. Other electrical sensors, such as an ultrasonic range sensor or a camera, could also be added to provide additional (and/or more precise) distance information or imagining capability to unmanned flying device  10 . A variety of antennas and transmitters could also be installed, thus providing unmanned flying device  10  with the ability to send or receive text messages or emails, broadcast emergency beacons or alerts or enhance the range of the user&#39;s radio or cellular phone. These sensors and electrical components could be mounted below, above or between the planes of the rotors due to the ability to route wires through the central shaft  25 . 
       FIG. 6  also shows the preferred wiring configuration between and among the components illustrated therein. 
     As can thus be seen, the present invention relates to an improved unmanned flying device (e.g. drone system) comprising a body and foldable blades, whereby rotation of the blades causes the blades to extend and deploy via centrifugal force. A collapsing force (e.g. via a spring or elastic element) causes the blades to automatically fold when not rotating (or rotating at a sufficiently low enough speed, as disclosed above). According to a preferred embodiment, the blades fold to conform to the device&#39;s body making the device  10  compact and provide protection for the blades. Preferably, the unmanned flying device of the present invention comprises a co-axial rotor design preferably comprising at least two rotors aligned on a central axis. Each rotor includes at least two blades which provide a propulsive lift when spun. The preferred embodiments may also comprise a camera for aerial surveillance. The device&#39;s compactness and durability make it easy to carry and use by hikers wishing to gain an aerial view of the terrain. 
     The preferred embodiment utilizing two motors reduces the total size, weight and complexity compared to traditional multirotors. Additionally, the co-axial design allows the device&#39;s components in be located along a central shaft where they are easily protected by the outer shell  12 ,  14 ,  16 . The present invention can be remotely controlled using communications such as radio control (R/C), Bluetooth, a tether or other appropriate means. The device could also operate autonomously, making and directing flight decisions with the onboard computer processor or microcontroller  130  as well as the necessary supporting electrical sensors, motors, speed controllers and other components. The above system may be utilized in various applications including aerial surveillance, delivery, amusement (e.g. helicopter toys), applications for similar drone systems which are currently used or will become available with emerging technologies. The present invention is also well suited for use by hikers wherein the compact and light design may be placed in a backpack, and used for surveillance of hidden terrain. 
     Preferably, device  10  can be hand launched and is capable of quickly ascending to several hundred feet. Furthermore, device  10  may be manufactured by methods such as  3 D printing, injection molding, etc. or combinations thereof. In a preferred embodiment, the overall size of the unmanned flying device  10  is approximately 15 inches. 
     While the foregoing are preferred embodiment constructions of the present invention, it should be understood that other contemplated alternative embodiments may comprise a wide range of different motors, electronic speed controllers and battery types, voltages and capacitance to optimize performance, as should be understood in the art. 
     It can thus be seen that the present invention provides for an improved unmanned flying device over that currently found in the art. In particular, the present invention provides an improved unmanned flying device construction that can be utilized for a variety of applications, including aerial surveillance, amusement, and the delivery of items. Most significantly and among other things, the present invention provides an improved unmanned flying device construction that is both convenient and practical to use, and that is also compact, durable and can be manufactured at a relatively low cost and that includes blades which are biased towards folding to conform to the body of the unmanned flying device so as to minimize or prevent, among other things, damage to the device itself upon a landing or crash. 
     As noted above, the biasing of the torsion springs or other biasing devices as disclosed herein act to collapse the blades to preferably the profile of the unmanned flying device  10 . As also stated above, collapsing the blades to be parallel to the body of the device when in their collapsed position is preferred, although at least essentially parallel is intended to mean within about 90% and also preferred. However, for the avoidance of doubt, the collapsing of the blades must be at least 45 degrees down. In this way, the present invention is patentably distinguishable from other merely “flapping”, whereby the present invention provides that the blades “collapse” such that they are folded down and away from a position where they produce the necessary aerodynamic lift in the “up” direction needed for controlled flight. As discussed earlier herein, a controlled flight may still yield that the blades “flap” about +1-15 degrees away from perpendicular due to control inputs and blade coning. As would be understood by those skilled in the art, after a collapse of 45 degrees or greater there will not be any further controlled flight. In the foregoing way, the present invention achieves the objectives and advantages set forth herein, and in this way, patentability distinguishes the claimed invention from other blades which might sag or otherwise bend simply due to their own weight or component tolerances of the rotor arms, etc. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It should also be understood that the following claims are intended to cover all of the generic and specific features of the invention described herein and all statements of the scope of the invention that as a matter of language might fall therebetween. 
     To be sure, the present invention is applicable to a wide variety of devices and applications. That is, while the following embodiments have been disclosed with reference to an unmanned flying device, such a general description is intended to include, and therefore should be understood and deemed to encompass devices such as unmanned drones, and drones as would be used in the recreational sense.