Patent Publication Number: US-2022234728-A1

Title: Method and Apparatus for Reducing Download and Drag of VTOL Electric Vehicle

Description:
TECHNICAL FIELD 
     The present disclosure is directed to aircraft design and more particularly to aerodynamic design for booms and rotors. 
     BACKGROUND OF THE INVENTION 
     Electric vehicles are becoming more and more prevalent. Electric vehicles can be difficult to implement in aircraft because of the heavy weight of batteries. Because of the weight problem, any advantage in minimizing drag and download can be very valuable. Mitigating download can allow an aircraft to take off heavier. 
     BRIEF SUMMARY OF THE INVENTION 
     One embodiment under the present disclosure can comprise a vertical takeoff and landing aircraft. The aircraft can comprise a fuselage and one or more wings coupled to the fuselage. It can further comprise one or more booms coupled to the fuselage by the one or more wings, wherein the one or more booms comprise one or more rotors on a ground facing side, and further comprising one or more doors operable to house the one or more rotors during forward flight and to retract and allow use of the one or more rotors during vertical takeoff and landing. 
     Another embodiment can comprise a method of manufacturing an aircraft for vertical takeoff and landing. The method can comprise providing a fuselage; coupling one or more wings to the fuselage; coupling one or more booms to the one or more wings; and coupling one or more rotors within the one or more booms, the one or more rotors ground-facing and operable for vertical takeoff and landing. It can further comprise providing one or more doors on the one or more booms, the one or more doors configured to house the one or more rotors during forward flight and to retract and expose the one or more rotors during vertical takeoff and landing. 
     Another embodiment under the present disclosure can comprise a method of operating an aircraft. The method can comprise retracting one or more doors located on one or more booms of the aircraft to reveal one or more rotors; providing thrust for vertical takeoff by the one or more rotors, wherein the one or more rotors are coupled to an underside of the one or more booms; once the aircraft is airborne, providing forward thrust and closing the one or more doors to conceal the one or more rotors within the one or more booms; slowing the aircraft and retracting the one or more doors to reveal the one or more rotors; and providing thrust for vertical landing by the one or more rotors. 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  shows a prior art embodiment. 
         FIGS. 2A-2B  show schematic views of an aircraft embodiment under the present disclosure. 
         FIGS. 3A-3D  show schematic views of an aircraft embodiment under the present disclosure. 
         FIGS. 4A-4D  show schematic views of an aircraft embodiment under the present disclosure. 
         FIG. 5  shows schematic views of an aircraft embodiment under the present disclosure. 
         FIGS. 6A-6E  show door embodiments under the present disclosure. 
         FIGS. 7A-7B  show door actuator embodiments under the present disclosure. 
         FIG. 8  shows a flow chart of a method embodiment under the present disclosure. 
         FIG. 9  shows a flow chart of a method embodiment under the present disclosure. 
         FIGS. 10A-10B  show schematic views of an aircraft embodiment under the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a prior art aircraft can be seen. Aircraft  100  comprises two booms  130 ,  140 , cockpit and body  150 , and wing  120 . Rotors  110  sit on top of booms  130 ,  140 . In the displayed configuration booms  130 ,  140  obstruct the thrust or thrust created by the rotors in hover mode. In forward flight, rotors  110  create drag. During flight the rotor blades are configured to sit parallel to the booms but drag is still created. 
       FIGS. 2A-2B, 3A-3D, and 4A-4D  display an embodiment of a VTOL (vertical takeoff and landing) aircraft under the current disclosure. 
     As shown in  FIG. 2A , embodiments under the present disclosure can comprise booms  230 ,  240  that comprise rotors  210  underneath. Aircraft  200  comprises booms  230 ,  240 , fuselage  250 , wing  220 , and fin  270 . Booms  230 ,  240  comprise doors  260  which can lift vertically to expose rotors  210 . This embodiment allows the rotors  210  to apply maximum thrust during hover mode—because the boom does not get in the way. Furthermore, during forward flight, the doors  260  can be closed to prevent rotors  210  from creating drag.  FIG. 2B  shows aircraft  200  with the doors  260  closed such as in forward flight. 
       FIGS. 3A-3D  show further views of aircraft  200  while the doors  260  are closed.  FIG. 3A  shows a top-down view.  FIG. 3B  shows a side-profile view.  FIG. 3C  shows a front view.  FIG. 3D  shows a bottom-up view. 
       FIGS. 4A-4D  show further views of aircraft  200  while the doors  260  are open.  FIG. 4A  shows a top-down view.  FIG. 4B  shows a side-profile view.  FIG. 4C  shows a front view.  FIG. 4D  shows a bottom-up view. As can be seen in  FIG. 4C , doors  260  can be configured to sit close to booms  230 ,  240  even in open position. Furthermore, rotors  210 , when not spinning, can be hidden from a front-view, also helping minimize drag. 
     Aircraft  200  of the previous figures has been shown with eight rotors  210  and two booms  230 ,  240 . However, the present disclosure includes other arrangements. For example, aircraft  500  of  FIG. 5  comprises four booms  530 ,  535 ,  540 ,  545 . Rotors  510  are located on each boom, but here there are two rotors  510  per boom. Fuselage  570 , wing  520  and fin  570  are also shown. Doors  560  can open and close as in other embodiments. Any appropriate number of booms, wings, fins, and other elements are possible. It is preferred that each rotor comprise two blades in linear position with each other, such that the blades can rest within the boom during forward flight. While a preferred embodiment of the present disclosure comprises an electric aircraft, fuel-based aircraft are possible as well. 
       FIGS. 6A-6E  show a possible embodiment of the doors on the booms shown in earlier figures. As seen, doors  660  are located on boom  640  and can house rotors (not shown). In this embodiment, a four-bar linkage comprising upper bars  680  and lower bars  690  can operate the opening and closing of doors  660 . It is preferable that the default position of doors  660  be open (other arrangements are possible). That way, if there is a failure, the default position would be open, allowing the rotors to be used for takeoff and landing. Springs about the base of arms  680 ,  690  may be set to be neutral at the open position—and force would be used to maintain the doors  680 ,  690  in a closed position. Springs could be rotational about the base of arms  680 ,  690 , or linearly actuated and connected at another part of arms  680 ,  690 . It is preferable that the doors  660 , when open as in  FIG. 6E , rest close to the surface of boom  640 . This will cause less drag. 
     A variety of actuator options are available for moving arms  680 ,  690 . A single linear actuator per door set is possible, operating both left and right doors simultaneously. A single linear actuator per boom is possible, or multiple actuators.  FIGS. 7A and 7B  show a possible actuator embodiment. Doors  760  are located on booms  740 . Upper bars  780  and lower bars  790  can open and close doors  760 . Actuator  775  show possible means of applying force to open or close doors  760 . Actuator  775  can pull cable  777  that runs around pulleys  765  and connects to door  780 . When actuator  775  lowers it pulls cable  777  and thereby opens door  760 .  FIG. 7A  shows doors  760  in a closed state while  FIG. 7B  shows an open state. A variety of other actuator embodiments are possible. 
       FIG. 8  shows a possible method embodiment  800  of manufacturing an aircraft under the present disclosure. At  810 , a fuselage is provided. At  820 , one or more wings are coupled to the fuselage. At  830 , one or more booms are coupled to the one or more wings. At  840 , one or more rotors are coupled within/to the one or more booms, the one or more rotors ground-facing and operable for vertical takeoff and landing. At  850 , one or more doors are provided on the one or more booms, the one or more doors configured to house the one or more rotors during forward flight and to retract and expose the one or more rotors during vertical takeoff and landing. 
       FIG. 9  shows a possible method embodiment  900  for operating an aircraft under the present disclosure. At  910 , one or more doors located on one or more booms can be retracted to reveal one or more rotors, wherein the one or more rotors are coupled to an underside of the one or more booms. At  920 , the one or more rotors can provide thrust for vertical takeoff. At  930 , once the aircraft is airborne, provide forward thrust and close the one or more doors to conceal the one or more rotors within the one or more booms. At  940 , the aircraft can be slowed and the one or more doors can be retracted to reveal the one or more rotors. At  950 , the one or more rotors provide thrust for vertical landing. 
     Another embodiment under the present disclosure can comprise an aircraft such as shown in  FIG. 2 , but with slightly canted booms. Such an embodiment would put the rotors at a slight outward-facing angle. This embodiment gives the aircraft some maneuverability advantages over non-canted embodiments. Such an embodiment can be seen in aircraft  1000  of  FIGS. 10A-10B . Aircraft  1000  has booms  1040 , fuselage  1050 , and wings  2020 . Doors  1060  are in a closed position concealing rotors (not shown). Booms  1040  can be canted slightly outward by an angle α. In this embodiment angle α is small, less than 10 degrees, but a variety of angles are possible. Wings  1020  are shown to extend upward from the fuselage at an angle. A portion of wings  1020  that are outboard of the booms  1040  can extend horizontally or at an angle. A variety of angled positions are possible for the wings  1020  and the booms  1040 . One of the benefits of the embodiment of  FIGS. 10A-10B  is greater maneuverability for yaw. 
     Aircraft such as described in  FIGS. 2 and 10  often have a hover mode and a forward flight mode. In hover mode, the rotors on the booms are used to provide lift. In order to pitch the aircraft, more thrust is provided to the front rotors (or rear rotors depending on the design). Thrust can be increased on one side or the other to achieve roll movement. To yaw the aircraft torque should increase on opposite rotors (front left and rear right rotors, for example). Ailerons and rudders can be used on the wings or fins to assist in aircraft movement, such as for yawing. An elevator can be used on a horizontal tail for additional maneuverability. 
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.