Abstract:
An unmanned aerial vehicle (UAV) comprising a plurality of propeller drives rigidly mounted to a foldable frame with the motor rotors aligned in a vertical direction to provide a means of vertical takeoffs and landings. The foldable frame mounts a sheet sail at an angle with the horizontal that provides lift during the forward motion and tilt of the UAV. In one embodiment the shape of the sheet sail and frame are triangular with one or two propeller drives being mounted in close proximity to each of the three vertices. In another embodiment, the shape of the sheet sail and frame are triangular with one or two propeller drives being mounted in close proximity to each of the three vertices, and one or two propeller drives being mount in close proximity to the trailing edge of the spine, in between the trailing edge propeller drives. In some embodiments, the frame spars may be comprised of carbon fiber rods and the sheet sail may be comprised of ripstop nylon fabric.

Description:
[0001]    Embodiments of the invention relate generally to Unmanned Aerial Vehicles (UAVs), personal drones, and, more particularly to multicopters with various configurations of rotary propeller drives and to fixed wing planes and combinations thereof. 
       BACKGROUND 
       [0002]    An Unmanned Aerial Vehicle (UAV), commonly referred to as a drone, is an aircraft without a human pilot. It is controlled either by remote control using a radio signal, or, autonomously using an onboard computer system. UAVs are commonly used in military operations where missions are often too hazardous to deploy manned aircraft. 
         [0003]    The use of personal drones has become increasingly popular over the last few years. Manufacturers have developed a wide variety of multicopters with three or more rotary propellers that are used for lift and propulsion, with the most popular version being a four rotor quadcopter. Advances in microelectromechancial system (MEMS) gyroscopes and accelerometers have allowed onboard computers to autonomously sense and control the pitch, roll, and yaw of these rotary multicopters. Some advanced personal drones are also equipped with global positioning systems (GPS) and compass microcircuits that allow the onboard computer to fly autonomously between preprogrammed waypoints. These systems also allow the multicopters to return safely to a home position given a low battery or lost telemetry signal situation. Multicopters are often equipped with a camera system for aerial photography. The main advantage of a multicopter its flight maneuverability including vertical takeoffs, landings, and the ability to hover in a fixed position. The main limitation of a multicopter is its limited flight time due to battery charge limitations. The typical flight time for a personal multicopter drone is 5-15 minutes. 
         [0004]    Another common type of personal drone is a rotary propeller powered fixed wing plane. Fixed wing planes typically cost more than multicopters because they require servos and linkages to actuate flight control surfaces such as ailerons, a rudder, and an elevator. Fixed wing drones can be equipped with all of the sensors and onboard computers used by multicopters for autonomous flight. The main advantage of fixed wing planes is their longer flight time, typically 30-60 minutes on a battery charge. Flight time is extended because the wings provide lift. The main disadvantage of fixed wing planes is their limited flight maneuverability. Because they require a forward thrust to provide lift, they cannot perform vertical takeoffs and landings, and they cannot hover in a fixed position in space. 
         [0005]    There are personal drones that integrate a multicopter platform with a fixed wing aircraft design. These personal drones typically use four propeller drives oriented in the vertical position for vertical takeoff capability. Once at cruising attitude, motorized mechanisms rotate the propeller drives towards the horizontal position and the aircraft functions as a fixed wing plane. These hybrid drones are costly because they require additional motors and linkages to tilt multiple propeller drives. These drones are often quite large because of their fixed wingspans, making them difficult to store and transport. 
       SUMMARY 
       [0006]    The embodiments of the invention provide the vertical takeoff and hovering capability of multicopters with the extended flight times and maneuverability of fixed wing aircraft, without any additional motors and linkages to rotate propellers drives, or to actuate flight control surfaces. 
         [0007]    The added cost and complexity of a conventional fixed wing plane design using servos and linkages to control flight control surfaces is not required because pitch, roll, yaw and forward thrust are all enabled using the multiple vertically mounted propeller drives by the same means as a multicopter. 
         [0008]    The added cost and complexity of using motors and linkages to rotate multiple propeller drives in a fixed wing personal drone from a vertical to horizontal thrust direction as a means of providing vertical takeoffs is not required with the invention. The invention, along with conventional multicopters, move forward by tilting the aircraft frame and the subsequent propeller thrust vector (e.g., 1-30 degrees from horizontal), towards the direction of forward motion. The invention angles the wing control surface from horizontal so that it provides lift and minimal drag in this tilted forward thrust position. 
         [0009]    To further reduce cost, weight, and complexity, the invention uses a wing comprised of a lightweight rigid frame (e.g. carbon, aluminum, or fiberglass tubing or rods) that supports a sheet sail (e.g. ripstop nylon fabric) such as those found in many kite designs. 
         [0010]    A further advantage of the invention is the ability to fold into a compact size. This is a major advantage in transporting the personal drone, as fixed wing designs can be large in size, with wings that often span 3-5 feet. By removing the spreader spars, the fabric sail and leading edge spars can be rotated together to form a compact shape for easy transport and storage. 
         [0011]    The placement and quantity of the propeller drives can vary; typically the number of propeller drives is an even number so that the propellers can spin in opposing directions to cancel out any resultant torsional forces on the vehicle. Additional propeller drives typically provide additional lift to enable heavier payloads to be carried. 
         [0012]    In one embodiment, the frame of the invention is triangular in shape and the sheet sail forms a delta wing. One or two propeller drives are mounted in close proximity to the leading edge vertex of the delta wing, and one or two propeller drives are mounted at each of the trailing edge vertices. 
         [0013]    In another embodiment, the frame of the invention is triangular in shape and the sheet sail forms a delta wing. One or two propeller drives are mounted in close proximity to each of the three triangular vertices, and one or two propeller drives are mounted in close proximity to the trailing end of the spine spar, in between the two trailing vertices. 
         [0014]    The above summary is not intended to describe each embodiment or every implementation of the invention. Rather, a more complete understanding of the invention will become apparent and appreciated by reference to the following Detailed Description of Exemplary Embodiments and claims in view of the accompanying figures of the drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING 
         [0015]    The invention will be further described with reference to the figures of the drawing, wherein: 
           [0016]      FIG. 1  is a front isometric view of the vertical takeoff winged multicopter in accordance with one embodiment of the invention; 
           [0017]      FIG. 2  is a rear isometric view of the vertical takeoff winged multicopter, with the sheet sail removed for clarity; 
           [0018]      FIG. 3  is a front view of the vertical takeoff winged multicopter as it sits on the ground prior to flight; 
           [0019]      FIG. 4  is a front isometric view of the sheet sail; 
           [0020]      FIG. 5  is an enlarged rear isometric view of the front motor mount; 
           [0021]      FIG. 6  is a rear isometric view of the vertical takeoff winged multicopter in a folded position with the sheet sail removed for clarity; 
           [0022]      FIG. 7  is an enlarged front section view of the front motor mount; 
           [0023]      FIG. 8  is an enlarged isometric view of the left spreader connector; 
           [0024]      FIG. 9  is an enlarged front section view of the side motor mount; 
           [0025]      FIG. 10  is an enlarged exploded isometric view of the electronics housing assembly; 
           [0026]      FIG. 11  is an enlarged front section view of the electronics assembly; 
           [0027]      FIG. 12  is an enlarged isometric view of the electronic components; 
           [0028]      FIG. 13  is a rear isometric view of another embodiment of the vertical takeoff winged multicopter with a rear mounted propeller drive; 
           [0029]      FIG. 14  is a front view of the vertical takeoff winged multicopter in the forward thrust position; 
       
    
    
       [0030]    The figures are rendered primarily for clarity and are not necessarily drawn to scale. Moreover, various structure/components, including but not limited to fasteners, electrical components (wiring, cables, etc.), and the like, may be removed from some or all of the views where inclusion of such structure/components is not necessary to understand the various exemplary embodiments of the invention. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0031]    In the following detailed description of illustrative embodiments of the invention, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments in which the invention may be practiced. 
         [0032]    Embodiments of the invention are directed generally to Unmanned Aerial Vehicles (UAVs) also referred to herein as “personal drones”. While the embodiments of this invention use a triangular, delta wing configuration, other wing shapes may be used without departing from the scope of the invention. 
         [0033]    It is understood that individual parts may be assembled by several different means including, but not limited to, screws, bolts, adhesives, pins, retaining rings, press fits etc. without departing from the scope of the invention. 
         [0034]    For simplicity, the wiring between electrical components and the motor drives has been eliminated. It is understood that all of the electrical components are connected by some form of wiring. 
         [0035]      FIG. 1  and  FIG. 2  are front and rear isometric views of one embodiment of the invention. The frame spars  12 ,  14 ,  16 ,  18   a  and  18   b  form a triangular frame that supports a sheet sail  10  wing. In one embodiment the spars may consist of pultruded carbon tubes distributed by Goodwinds and be approximately 0.375 inches in diameter. Propeller drives  36   a - d  are mounted near the vertices of the triangular frame. 
         [0036]    Propeller drive  36   a  is rigidly attached to front motor mount  24  and propeller drive  36   b  is rigidly attached to front motor mount  24  along the same axis. The propeller drives  36   a  and  36   b  spin in opposite directions in order to cancel out any net torsional forces, and the propellers are mounted as a means to provide thrust in the same upward direction. 
         [0037]    Propeller drive  36   c  is attached to side motor mount  26   a,  and propeller drive  36   d  is attached to side motor mount  26   b.  Both of these drives are aligned as a means to provide thrust in the same upward direction and they spin in opposite directions to cancel out any net torsional forces on the invention. 
         [0038]    The front motor mount  24  is pivotally attached to the right leading edge spar  12 , and the left leading edge spar  14 . The front motor mount  24  is rigidly fixated to the spine spar  16 . The electronics assembly  34  is rigidly fixated to the spine spar  16  and stabilized by rigid fixations to the spreader spars  18   a  and  18   b.  The motor mounts may be comprised of injection molded plastic, 3D printed plastic, or made of a lightweight cast material. 
         [0039]      FIG. 3  is a front view of the invention as it sits on the ground prior to flight. All of the propeller drives  36   a - 36   d  have motor rotor axes aligned in the vertical direction which provides a means of vertical takeoff in the same manner as conventional multicopters. The invention rests on three points, the foot  22 , and the two foot pad features  42   a  and  42   b  on the side mounts  26   a  and  26   b  respectively. In one embodiment, the foot  22  is a plastic part assembled to the foot spar  20 . The frame spars  12 ,  14 , and  16  are angled relative the ground plane  40 . The sheet sail  10  follows this frame angle and forms the sheet sail design angle from horizontal  168  (e.g., 10 to 70 degrees). 
         [0040]      FIG. 4  is a front isometric view of the sheet sail  10 . In one embodiment the sheet sail is comprised of ripstop nylon fabric. The seams  50 ,  52   a  and  52   b  may be sewn into the fabric sheet sail  10 . The right leading edge spar  12  (as shown in  FIG. 2 ) passes through the right leading edge seam  50   a,  the left leading edge spar  14  passes through the left leading edge seam  50   b  and the spine spar  16  passes through the spine seam  52  which captivates the sheet sail  10  to the frame. The seams  50 ,  52   a  and  52   b  offer a convenient passage to route the wires that travel between the electronics assembly  34  and the propeller drives. 
         [0041]    A front motor mount cutout  58  provides clearance in the sheet sail  10  for the front motor mount  24 . A right spreader connector cutout  54   a  provides clearance in the sheet sail  10  for the right spreader connector  30 , and the left spreader connector cutout  54   b  provides clearance in the sheet sail  10  for the left spreader connector  32 . Additional cutouts  56   a  and  56   b  are cutouts in the spine seam  52  to provide clearance for connections to the electronics assembly  34 . 
         [0042]      FIG. 5  is an enlarged rear isometric view of the front motor mount  24 . The propeller drives  36   a,    36   b,    36   c  and  36   d  are comprised of an electric motor  60 , a propeller  62 , and a propeller nut assembly  64 . The high torque, direct current motor  24  is designed specifically for personal multicopters (e.g., 850 KV AC2830-358 distributed by 3D Robotics). The slow fly propeller  62  is designed for personal multicopters using electric motors (e.g., APC 10×47 Push Pull Propeller Set distributed by 3D Robotics). The left leading edge spar  14  pivots about pivot point  66   a,  and the right leading edge spar  12  pivots about pivot point  66   b.    
         [0043]      FIG. 6  is a rear isometric view of the vertical takeoff winged multicopter in a folded position with the sheet sail removed for clarity. Once the spreader spars  18   a  and  18   b  (see  FIG. 2 ) are removed, the left leading edge spar  14  and the right leading edge spar  12  are free to pivot inward about pivot points  66   a  and  66   b  respectively. The leading edge spars  14  and  12  rest on top of the electronics assembly  34 . The sheet sail  10  (not shown) collapses into the compact shape shown in  FIG. 6  for easy storage and transport. 
         [0044]      FIG. 7  is an enlarged front section view of the front motor mount  24 . The propeller drive  36   a  is assembled to the front motor mount wall  70   a  using two threaded fasteners (not shown) through holes  72 . The propeller drive  36   b  is assembled to the front motor mount wall  70   b  using two threaded fasteners (not shown) through holes  72 . The mounting bolt window  74  must have a sufficient height and width to allow a threaded fastener (not shown) to be inserted into the window, and then be inserted into holes  72 , and then to be secured by turning and tightening it from a hand tool (e.g., wrench) inserted into the window. In one embodiment the fastener is a hexagon headed threaded fastener and the tightening hand tool is a box wrench. 
         [0045]    The front motor mount  24  is fixated to the spine spar  16  by inserting it into a receiving hole  82 . The spine spar is further secured by inserting a shoulder screw  76   a  through a cross hole  80  whose axis is approximately normal to the receiving hole  82  axis. The shoulder screw  76   a  is secured using a locking nut  78   a.  The shoulder screw  76   a  and locking nut  78   a  are also used to create the pivot points  66   a  and  66   b  shown in  FIG. 5 , along with all other connections between the spars and motor mounts. The shoulder screws prevent any rotation between motor mounts which is imperative in keeping the thrust axes of the propeller drives in line with each other. There are many methods, besides a shoulder screw and nut to affix a mount with a spar, or to create a pivot point between a mount and a spar (e.g., screws, bolts, adhesives, pins, retaining rings, press fits etc.). 
         [0046]      FIG. 8 . is an enlarged isometric view of the left spreader connector  32 . There is a left spreader connector  32  and a right spreader connector  30  (shown in  FIG. 2 ) because they are mirror images of each other, and the shoulder bolt  76   a  holes are in mirrored positions. The left spreader connector  32  is affixed to the left leading edge spar  14  using a through hole  90  and a shoulder screw  76   b  and locking nut (not shown). The spreader spar  18   a  is affixed to the left spreader connector  32  using a blind hole  92 . The compliance in the sheet sail  10  enables the left leading edge spar  14  to be stretched outward in order for the spreader spar  18   a  to be inserted into the blind hole  92  and for it to stay seated, the same means as a traditional kite spreader spar attachment. 
         [0047]      FIG. 9  is an enlarged front section view of the side motor mount  26   a.  The propeller drive  36   c  attachment is similar to the motor attachment in the front motor mount  24 , except with just a single motor to attach, the two threaded fasteners (not shown) pass through the holes  102  and through both side mount walls  100   a  and  100   b.  The side motor mount  26   a  is fixated to the right leading edge spar  12  by inserting it into a receiving hole  104 . The side motor mount  26   a  is further secured by inserting a shoulder screw  76   c  through a cross hole (not shown) whose axis is approximately normal to the receiving hole  104  axis. The shoulder screw  76   c  is secured using a locking nut (not shown). The propeller drive  36   d  is affixed to the side motor mount  26   b  (see  FIG. 2 ), and the side motor mount  26   b  is affixed to the left leading edge spar  14  in the same manner. 
         [0048]      FIG. 10  is an enlarged exploded isometric view of the electronics housing assembly  108 . The electronics housing  110  is designed as an injection molded part, but could also be a 3D printed part or cast in a lightweight material such as aluminum or titanium. On top of the electronics housing are two spine spar brackets  124   a  and  124   b  that contain through holes to attach to the spine spar  16 . Mounted between the two spine spar brackets  124   a  and  124   b  is a radio controlled receiver  128  that contains an antenna. The radio controlled receiver  128  is used to send control commands and flight status information back to a base station receiver (e.g., 915 MHz 3DR RC Receiver distributed by 3D Robotics). 
         [0049]    The electronics housing  110  contains several shelves  126  used to mount additional electronics components. A electronics housing cover  116  is fixated to the electronics housing  110  using three captivated thumb screws  118 . These thumb screws  118  screw into threaded inserts  120  that are sonically welded, or adhesively bonded to the electronics housing  110 . The threads could may also be directly cut into the plastic bosses in the electronics housing  110 . 
         [0050]    The spreader spar bracket  112  provides a foot mounting socket  132  for the foot spar  20  and two spreader spar mounting sockets  130   a  and  130   b  for the spreader spars  18   a  and  18   b  respectively. The spreader spars  18   a  and  18   b  and the foot spar  20  use shock cords (not shown) that are tied off inside the spreader spar bracket  112  to captivate the spars, and to prevent their loss during disassembly by the same means as the shock cording used in tent poles. The spreader spar bracket  112  is captivated in the electronics housing  110  by the use of bracket slots  114   a,    114   b,  and  114   c  in the electronics housing cover  116 . Vents  134  may be cut or molded into the electronics housing  110  and electronics housing cover  116  as means of providing air flow to cool heat producing electronics components. 
         [0051]      FIG. 11  is an enlarged front section view of the electronics assembly  34 . The spine spar  16  is fixated to the two spine spar brackets  124   a  and  124   b  using two shoulder screws  76   d  and  76   e  respectively. The foot  22  is attached to the foot spar  20  using a shoulder screw  76   f  and locking nut  78   f.  The electrical components are stacked on the shelves  126  of the electronics housing  110 . The bottom shelf may house the power distribution board  148  used to control and distribute the high currents sent to the motors  60  (e.g., Power Distribution Board distributed by 3D Robotics). This board may be mounted on standoffs  150  and small bolts and nuts (not shown). The second shelve may house the battery  146  (e.g., Lipro Power Pack 3s/11.1V 3500 mAh). Since the battery is frequently removed, it may just rest on the shelf and be centered using plastic ribs and foam cushioning (not shown). The third shelf may house the autopilot central processing unit  142  (e.g., Pixhawk PX4 Autopilot distributed by 3D Robotics). The autopilot unit  146  may be attached to the shelf using double backed very high bond (VHB) acrylic foam tape. The forth shelf may house the global positioning module  140  (e.g., 3DR uBlox GPS module distributed by 3D Robotics) and be mounted using standoffs  150  and small bolts and nuts (not shown). 
         [0052]    In order to evenly distribute the weight of all of the electrical components, they may be stacked on top of each other so that the center of mass of each component passes through the plane of symmetry of the invention as shown in  FIG. 12 . Maintaining symmetry for all of the components in the invention ensures a balanced weight distribution during flight. 
         [0053]      FIG. 13  is a rear isometric view of another embodiment of the vertical takeoff winged multicopter with a rear mounted propeller drive  36   b.  The propeller drive  36   b  is mounted to the rear motor mount  28 . The rear motor mount  28  is fixated to the back of the spine spar  16  using the same shoulder screw fixation method as the side mounts  26   a  and  26   b.  Additional embodiments may use two propeller drives at each mounting site and combinations thereof. All of these combinations are within the scope of the invention. 
         [0054]      FIG. 14  is a front view of the vertical takeoff winged multicopter in the forward thrust position. After the vertical takeoff winged multicopter has vertically ascended to cruising altitude in the position shown in  FIG. 3 , the frame tilts towards the direction of forward motion and the propeller thrust direction  160   a  and  160   b  changes from a purely vertical direction to a forward tilted position where a component of the thrust is vertical and a component of the thrust is in the horizontal forward thrust direction in the exact manner as a conventional multicopter. The sheet sail attack angle from horizontal  166  is the angle of the sheet sail  10  relative to the horizontal ground angle  164  during forward motion. This angle decreases as the vertical takeoff winged multicopter tilts forward, but it remains a positive angle (e.g., 5 to 20 degrees) in order to create a lift force  162  during forward motion. The sheet sail design angle from horizontal  168  (shown in  FIG. 3 ) may be tuned to create the optimum lift force  162  for a target cruising speed.