WO2021157736A1

WO2021157736A1 - Aerodynamic electric motor nacelle

Info

Publication number: WO2021157736A1
Application number: PCT/JP2021/004464
Authority: WO
Inventors: Greg T. Kendall
Original assignee: Hapsmobile Inc.
Priority date: 2020-02-06
Filing date: 2021-02-05
Publication date: 2021-08-12

Abstract

Systems, devices, and methods including one or more electric motor nacelles; and one or more electric motors attached to each of the one or more electric motor nacelles.

Description

AERODYNAMIC ELECTRIC MOTOR NACELLE

　　Embodiments relate generally to nacelles, and more particularly to an aerodynamic electric motor nacelle of an unmanned aerial vehicle.

Summary

　　A system embodiment may include: one or more electric motor nacelles; and one or more electric motors attached to each of the one or more electric motor nacelles.

　　Additional system embodiments may include: a wing of an unmanned aerial vehicle (UAV); and a spar disposed within the wing. In additional system embodiments, each electric motor nacelle may include a fillet disposed at an intersection where the wing meets a motor pylon of the electric motor nacelle to reduce drag. In additional system embodiments, each electric motor nacelle may beat an angle relative the wing. In additional system embodiments, the angle of the electric motor nacelle allows an axis of rotation of each motor to be parallel to a local airflow while the wing may beat a high angle of attack. In additional system embodiments, the angle of the electric motor nacelle may be such that a wake of a propeller attached to each electric motor remains below the wing.

　　In additional system embodiments, each electric motor nacelle comprises a pylon disposed outside of the wing. In additional system embodiments, the pylon comprises a stressed shell that provides structural support for each motor. In additional system embodiments, the pylon further comprises: an inlet disposed proximate a front of the pylon; a bulkhead disposed in the pylon; an inverter mounted to the bulkhead; and an outlet disposed past the bulkhead. In additional system embodiments, cooling air follows a path through the inlet, through the electric motor, past one or more inductors disposed within the pylon, through an opening in the bulkhead, and out of the outlet.

　　In additional system embodiments, the pylon may be a first forward section, and the electric motor nacelle may further comprise a second aft section disposed between a lower surface of the wing and the spar, where the second aft section may be disposed within the wing. In additional system embodiments, the pylon absorbs torsional loads, bending loads, and thrust loads. In additional system embodiments, a star-shaped motor mount may be disposed on a front of the pylon connects the electric motor to the pylon.

　　The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the invention. Like reference numerals designate corresponding parts throughout the different views. Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which:
[Fig. 1] FIG. 1 depicts an electric motor nacelle system of an unmanned aerial vehicle;
[Fig. 2] FIG. 2 depicts a side perspective view of a motor pylon of the electric motor nacelle system of FIG. 1;
[Fig. 3] FIG. 3 depicts a front perspective view of the motor pylon of FIG. 2;
[Fig. 4] FIG. 4 depicts a top perspective view of the mounting flange area of the motor pylon of FIG. 2;
[Fig. 5] FIG. 5 depicts a plan view of a flange of the motor pylon of FIG. 2 configured for attachment to a wing panel associated with the system of FIG. 1; and
[Fig. 6] FIG. 6 depicts a front view of the motor pylon of FIG. 1 attached to the wing panel of FIG. 5.

　　With respect to FIG. 1, an electric motor nacelle system 10 of an unmanned aerial vehicle (UAV) is depicted. The system 10 includes an electric motor nacelle 100, a wing 101 with a leading edge 105 and a spar 111. The system 10 may further include a propeller 109 and a pylon 113 housing a motor 107.

　　UAVs are aircraft with no onboard pilot and may fly autonomously or remotely. In one embodiment, the UAV is a high altitude long endurance aircraft. In one embodiment, the UAV may have one or more electric motors, for example, between one and forty (40) motors, and a wingspan between one hundred (100) feet and four hundred (400) feet. In one embodiment, the UAV has a wingspan of approximately two hundred sixty (260) feet and is propelled by a plurality of propellers coupled to a plurality of motors, for example, ten (10) electric motors, powered by a solar array covering the surface of the wing, resulting in zero emissions. Flying at an altitude of approximately sixty five thousand (65,000) feet above sea level and above the clouds, the UAV is designed for continuous, extended missions of up to months without landing.

　　The UAV functions optimally at high altitude and is capable of considerable periods of sustained flight without recourse to land. In one embodiment, the UAV may weigh approximately three thousand (3,000) lbs.

　　In one embodiment, there may be one electric motor nacelle 100 for each motor 107 of the UAV. The motor nacelle 100 may produce a smooth, contoured outline and reduce drag. The electric motor nacelle 100 may also provide for a fillet 121 (see FIG. 6) to fair the intersection where the wing 101 meets the pylon structure 113 to reduce drag, such as interference drag and may reduce or eliminate separation of the airflow in the region of the junction of the motor pylon 113 to the UAV wing 101 and thereby reduce drag on the UAV. In one embodiment, the electric nacelle 100 is angled with respect to the wing 101 to allow the axis of rotation of the propeller 109 to be parallel to the local airflow while the wing 101 is at a high angle of attack. In one embodiment, the electric motor nacelle 100 is positioned such that the wake of the electric motor nacelle 100 remains below the wing 101 to minimize the aerodynamic drag of the wing 101.

　　In one embodiment, the motor pylon 113 is made of carbon fiber. In another embodiment, the motor pylon 113 is constructed from a carbon fiber and foam composite. In one embodiment, the pylon 113 has the form of a stressed shell that provides structural support for the motor 107 while also having an aerodynamic shape.

　　In one embodiment, an outlet 134 is a pair of slots in the bottom of the pylon structure 113. The outlet 134 may have approximately the same area as an inlet 130. The outlet 134 may incorporate louvers to help turn the exiting flow though the pylon structure 113 to reduce drag. The flow path of the cooling air may have the following path: through the inlet 130 (located in the center of a spinner 140), then through the motor 107 (which is mostly hollow), into the pylon structure 113, past a plurality of inductors 136 (which cools the inductors 136), through an opening in a bulkhead 138 that has an inverter 139 mounted thereto, and out of the outlet 134. The opening in the bulkhead 138 may include heat pipes with cooling fins. The heat pipes may carry heat from the inverter 139 to the cooling fins, which are in the internal cooling flow. In one embodiment, there are no inductors 136 associated with the pylon structure 113.

　　In one embodiment, the pylon structure 113 has a first forward section that spans from the motor mount 132 to the lower surface of the wing 101. The pylon structure 113 has a second aft section 120 that goes from the lower surface of the wing 101 to the wing spar 111. The aft section 120 is inside the wing contour. The lower surface of the wing 101, where the first and second sections 120 of the pylon 113 come together, may consist of a thin polyvinyl fluoride (PVF) film, such as Tedlar film.

　　With respect to FIG. 2, the motor pylon 113 is illustrated. In one embodiment, the motor pylon 113 has a molded 3-D shape with a teardrop shaped forward body 102. The teardrop shaped body 102 then necks down into a narrow base 103 Thus, the motor pylon 113 has an aerodynamic shape. In one embodiment, the aerodynamic motor pylon 113 may absorb torsional loads, bending loads, and thrust loads. In one embodiment, there are aerodynamic and inertial loads (e.g., steady-state and cyclic) from the propeller 109, as well as loads resulting from the motor pylon 113 supporting its own mass and the mass of the motor 107, propeller 109, and the other installed components. All of these loads may be transmitted by the pylon 113 and the pylon mount 120 back to the wing 101, and the wing 101, in turn, opposes said loads.

　　With respect to FIG. 3, the teardrop shaped body 102 may house the motor 107. The teardrop shaped body 102 may have an opening 104, which is a forward edge of the pylon 113 (see also FIG. 1). In one embodiment, the inlet 130 is located at the center of a spinner (see FIG. 1), and has a diameter of approximately 4 inches. In one embodiment, the motor 107 may have approximately the same outer diameter as the opening 104, and the motor 107 is mounted forward of the opening 104. In one embodiment, the opening 104 may have a diameter slightly larger than the diameter of the motor to accommodate the motor inside the hollow, teardrop shaped body 102. The teardrop shaped body 102 may further include a plurality of holes 106 for securing the motor mount 132 and the motor 107 to the teardrop shaped body 102 at the opening 104. In one embodiment, each hole 106 receives a bolt that secures the opening 104 to the outside of the motor mount 132. Access to the inside of the pylon 113 may be gained by removing the bolts and separating the motor mount 132 from the pylon 113.

　　With respect to FIG. 4, the aerodynamic electric motor nacelle's 100 shape transitions from the circular opening 104 of the teardrop shaped body 102 to an elliptical opening 108 of the base 103, the elliptical opening 108 resulting from an angled cross section of the base 103.

　　The opening 108 may have a flange 110 with the same elliptical shape that extends out from the opening 108. In one embodiment, the flange 110 extends about 1.0 inches perpendicularly from the openings 108. The flange 110 includes holes 112. In one embodiment, the flange includes six holes 112. The holes 112 may receive bolts for attaching the pylon 113 to the pylon mount 120, which is bonded to the spar 111 of a wing panel 114 of the UAV, as described below.

　　FIG. 5 shows a plan view of the connection of the flange 110 of the motor pylon to the underside of a wing panel 114 of the UAV. The remainder of the motor nacelle (e.g., the pylon 113 and motor 107) has been removed for clarity. In one embodiment, the wing panel 114 has more than one motor nacelle 100 and an associated motor. The contour of the mounting flange 110 matches the surface shape of the wing panel 114 to provide a flush connection with no spaces or gaps. Each hole 112 (see FIG. 3) has a bolt 116. Each hole 112 of the corresponding flange of the pylon mount 120 may have a nut plate bonded in place.

　　With respect to FIG. 6, the motor pylon 113 is shown connected chordwise to the wing panel 114. For connection of the motor pylon 113 to the wing panel 114, the second, aft section 120 (see also FIG. 1) seats flush on the inside of the wing panel 114 and receives the bolts 116 for a secure connection of the motor pylon 113 to the wing panel 114. In one embodiment, the upper portion 122 may be bonded to the spar 111 of the wing panel 114. In one embodiment, the second section 120 of the pylon structure has an additional molded-in flange that mates with the outside shape of the spar 111, which is close to cylindrical shaped. Additional plies may wrap around the spar 111 and over the molded-in flanges to tie the structure together. In one embodiment, the base 124 has corresponding holes for receiving the bolts 116. In one embodiment, the shape of face of the base 124 is approximately the same as the flange 110. In one embodiment, the base 124 is made of carbon fiber. In one embodiment, all of the load (e.g., torsional loads, bending loads, and thrust loads) may be transferred through the bolts 116. In one embodiment, the limit load is +5.0 / -3.0 gs vertical and ±2.0 gs horizontal.

　　In one embodiment, the vertical and lateral natural frequencies of the pylon structure 113 can be tuned (in design) by adjusting the major and minor dimensions of the mount cross section 108.

　　In one embodiment, a star-shaped motor mount 132 is bolted into the front of the pylon structure 113. The star-shaped motor mount 132 may be secured to the pylon structure 113 via bolts passed through the holes 106 (see FIG. 3) the pylon structure 113 and into the perimeter of the star-shaped motor mount 132. The hub of the motor 107 may be bolted to the center of the star shaped mount 132.

　　It is contemplated that various combinations and/or sub-combinations of the specific features and aspects of the above embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments may be combined with or substituted for one another in order to form varying modes of the disclosed invention. Further, it is intended that the scope of the present invention is herein disclosed by way of examples and should not be limited by the particular disclosed embodiments described above.

Claims

　　A system comprising:
　　one or more electric motor nacelles (100); and
　　one or more electric motors attached to each of the one or more electric motor nacelles.
　　The system of claim 1 further comprising:
　　a wing of an unmanned aerial vehicle (UAV); and
　　a spar disposed within the wing.
　　The system of claim 2, wherein the one or more electric motor nacelles are attached to the spar.
　　The system of claim 2 or 3, wherein each electric motor nacelle comprises a fillet disposed at an intersection wherein the wing meets a motor pylon of the electric motor nacelle to reduce drag.
　　The system of any one of claims 2 to 4, wherein each electric motor nacelle is at an angle relative the wing.
　　The system of claim 5, wherein the angle of the electric motor nacelle allows an axis of rotation of each motor to be parallel to a local airflow while the wing is at a high angle of attack.
　　The system of claim 5, wherein the angle of the electric motor nacelle is such that a wake of a propeller attached to each electric motor remains below the wing.
　　The system of any one of claims 2 to 7, wherein each electric motor nacelle comprises a pylon disposed outside of the wing.
　　The system of claim 8, wherein the pylon comprises a stressed shell that provides structural support for each motor.
　　The system of claim 8 or 9, wherein the pylon further comprises:
　　an inlet disposed proximate a front of the pylon;
　　a bulkhead disposed in the pylon;
　　an inverter mounted to the bulkhead; and
　　an outlet disposed past the bulkhead.
　　The system of claim 10, wherein cooling air follows a path through the inlet, through the electric motor, past one or more inductors disposed within the pylon, through an opening in the bulkhead, and out of the outlet (134).
　　The system of claim 11, the opening in the bulkhead includes heat pipes with cooling fins.
　　The system of claim 12, wherein the heat pipe is carry heat from the inverter to the cooling fins, which are in the internal cooling flow.
　　The system of any one of claims 8, to 13 wherein the pylon is a first forward section, and wherein the electric motor nacelle further comprises a second aft section disposed between a lower surface of the wing and the spar, wherein the second aft section is disposed within the wing.
　　The system of any one of claims 8 to 14, wherein the pylon absorbs torsional loads, bending loads, and thrust loads.
　　The system of any one of claims 8 to 15, wherein a star-shaped motor mount disposed on a front of the pylon connects the electric motor to the pylon.
　　The system of claim 16, a hub of the electric motor is bolted to the center of the star-shaped motor mount.