WO2021157672A1

WO2021157672A1 - Trailing edge spar connection for an unmanned aerial vehicle

Info

Publication number: WO2021157672A1
Application number: PCT/JP2021/004182
Authority: WO
Inventors: Emil Ghapgharan
Original assignee: Hapsmobile Inc.
Priority date: 2020-02-04
Filing date: 2021-02-04
Publication date: 2021-08-12

Abstract

Systems, devices, and methods including two or more wing panels; and one or more trailing edge spar connector members configured to connect two adjacent wing panels of the two or more wing panel, where each trailing edge spar connector member comprises: a main body comprising two or more holes; two or more bushings for receiving two or more pins, where the two or more bushings hold the main body against a forward side of trailing edge spars of each wing panel, where an end of each bushing seats against an aft face of the main body; and where the two or more pins pass through the bushings and hole of the main body.

Description

TRAILING EDGE SPAR CONNECTION FOR AN UNMANNED AERIAL VEHICLE

　　Embodiments relate generally to wing structures, and more particularly to a trailing edge spar connection for an unmanned aerial vehicle.

Summary

　　A system embodiment may include: two or more wing panels, where each wing panel comprises: a cross-bracing element; an end rib, where the cross-bracing element may be connected to the end rib; and a trailing edge spar, where the end rib may be connected to the trailing edge spar, and where the trailing edge spar may be substantially hollow; one or more trailing edge spar connector members configured to connect two adjacent wing panels of the two or more wing panels, where each trailing edge spar connector member comprises: a main body comprising two or more holes; two or more bushings for receiving two or more pins, where the two or more bushings hold the main body against a forward side of the trailing edge spars, where an end of each bushing seats against an aft face of the main body; and where the two or more pins pass through the bushings and hole of the main body.

　　In additional system embodiments, the trailing edge spar may be made of carbon fiber. In additional system embodiments, each trailing edge spar connector member may fit inside the substantially hollow trailing edge spar of the two adjacent wing panels. In additional system embodiments, each trailing edge spar connector member may transfer a tensile load across the two adjacent wing panels.

　　In additional system embodiments, the pins may be clevis pins. In additional system embodiments, the clevis pins have a cylindrical body with a flat, circular head, and a diameter of the head may be slightly larger than a diameter of the body. In additional system embodiments, the bushings may be an annular cylinder with an inner diameter slightly larger than the diameter of the body of the pin.

　　In additional system embodiments, the two or more pins may extend out of the forward side of the main body. In additional system embodiments, one or more cotter pins may be placed through a hole at an end of each pin. In additional system embodiments, an inner portion of the main body may be thinner than each end of the main body.

　　In additional system embodiments, the forward side of the main body may comprise one or more elevated surfaces with beveled edges that ramp down to an inner portion. In additional system embodiments, the elevated surfaces may be shaped to conform to an inside of each of the trailing edge spars. In additional system embodiments, the main body may be made of titanium. In additional system embodiments, the two or more pins may be made of titanium. In additional system embodiments, each bushing may be made of at least one of: rubber, synthetic rubber, or polyurethane.

　　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 a top perspective view of an unmanned aerial vehicle;
[Fig. 2] FIG. 2 depicts a top perspective view of a two connected trailing edge spars of the unmanned aerial vehicle of FIG. 1;
[Fig. 3] FIG. 3 depicts the trailing edge spars of FIG. 2 in transparency with an exploded view of a trailing edge spar connector member;
[Fig. 4] FIG. 4 depicts a top perspective view of the trailing edge spar connector member of FIG. 3;
[Fig. 5] FIG. 5 depicts a front perspective view of a main body of the trailing edge spar connector member of FIG. 3;
[Fig. 6] FIG. 6 depicts a top perspective, enhanced, transparent view of the trailing edge spars of FIG. 2 connected with the trailing edge spar connector member of FIG. 3; and
[Fig. 7] FIG. 7 depicts a cross-sectional view of the trailing edge spars connected with the trailing edge spar connector member of FIG. 3.

　　With respect to FIG. 1, an unmanned aerial vehicle 100 (UAV) is depicted. UAVs are aircraft with no onboard pilot and may fly autonomously or remotely. In one embodiment, the UAV is a high altitude long endurance (HALE) aircraft. The UAV 100 may include wing panels 102. In one embodiment, the UAV 100 has seven (7) wing panels 102, including five (5) inner panels and two, outer wing tip panels. In one embodiment, the UAV may have one or more 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.

　　With respect to FIG. 2, two adjacent, inner wing panels 102 are shown. The thin film skin and solar modules of the wing panels 102 have been removed to highlight the interior structure of the wing panels 102. Each wing panel 102 includes a cross-bracing element 105 connected to an end rib 104. The end rib 104 may be further connected to an aft or "trailing edge" spar 106. The trailing edge spar 106 may be substantially hollow and made of carbon fiber.

　　With respect to FIG. 3, the two adjacent wing panels 102 of FIG. 2 are shown in transparency. An exploded view of a trailing edge spar connector member 130 is shown exterior to the two adjacent wing panels 102 for clarity. The trailing edge spar connector member 130 fits inside the two substantially hollow trailing edge spars 106. The trailing edge spar connector member 130 may be pinned to the spars 106, providing a secure internal connection for the two adjacent wing panels 102. This internal linkage provided by the trailing edge spar connector member 130 absorbs the tensile load across the spars 106.

　　The trailing edge spar connector member 130 may include a pair of bushings 132 for receiving a pair of clevis pins 134. The clevis pins 134 may have a cylindrical body 135 with a flat, circular head 136. The heads 136 may have a diameter slightly larger than the diameter of the clevis pin cylindrical body 135. Each bushing 132 may be an annular cylinder with an inner diameter slightly larger than the diameter of the clevis pin cylindrical body 135. Each bushing 132 may have an annular head 137. In one embodiment, the annular head 137 has a thickness of 0.75 inches. In one embodiment, each bushing 132 is 1.25 inches in length.

　　In one embodiment, when a clevis pin 134 is inserted into a bushing 132, the circular head 136 prevents the clevis pin 134 from passing all the way through the bushing 132. The bushings 132 may provide an interface between the clevis pins 134 and aft spar composite tube 106. The bushings 132 also hold the trailing edge spar connector member 130 against the forward sides of the aft spar tubes 106. In one embodiment, the forward sides of the aft spar tube 106 may be reinforced by a fitting 107 (see FIG. 7). In one embodiment, the fitting 107 is bonded to the end rib 104. In another embodiment, the fitting 107 is integrated into the end rib 104. In one embodiment, the clevis pins 134 and the main body 138 are made of titanium. In one embodiment, the main body 138 is made of aluminum. In one embodiment, the bushings 132 dampen the energy (e.g., vibrations) that may be partially transmitted through the bushing 132. In one embodiment, the bushings 132 are made of aluminum, rubber, synthetic rubber, or polyurethane. In one embodiment, the bushings 132 may allow a certain amount of movement. In one embodiment, the trailing edge spar 106, at limit load, may stretch up to 0.45 inches in between wing joints of adjacent wing panels.

　　With respect to FIG. 4, the trailing edge spar connector member 130 is shown assembled and in further detail. The end of each bushing 132 seats against an aft face 141 of the main body 138, such that the inner diameter of the annular bushings 132 lines up with a hole 140, e.g., an aperture, of the main body 138 (see also FIG. 3). In one embodiment, each hole 140 has approximately the same diameter as the inner diameter of the associated annular bushings 132. The clevis pins 134 pass through the bushings 132 and then through the hole 140, and extend out of a forward side 142 of the main body 138. In one embodiment, the circular head 136 prevents the clevis pin 134 from passing all the way through the bushing 132. A cotter pin 146 may be placed through a hole at the end of each clevis pin 134 (see also FIG. 3, ref no. 139). In one embodiment, the cotter pins 146 are metal "hairpin" or "R-clip" cotter pins. A washer 144 may be placed over the end of each clevis pin 134 and between the cotter pin 146 and the forward side of the composite aft spar tube 106.

　　The main body 138 may have curved sides 148 for optimum material thickness around the holes 140, which may provide for the carbon fiber main body 138 to be at an allowable stress when the trailing edge spar connector member 130 is at its design load. In one embodiment, if the carbon fiber material around the holes 140 is thinner (e.g., below the allowable stress), then the main body 138 may be too weak and may bend or even break. If the carbon fiber material around the holes 140 is too thick, then the main body 138, and hence, the trailing edge spar connector member 130, may be too heavy.

　　With respect to FIG. 5, the forward side 142 of the main body 138 is shown in further detail. In one embodiment, the forward side 142 has elevated surfaces 154 with beveled edges 150 that ramp down to an inner portion 152. Thus, the main body 138 is thinner at the inner portion 152 than at the ends. In one embodiment, the main body 138 has a width of 3.75 inches. The shape of the main body 138 may reduce weight. In one embodiment, if the main body 138 was not thinner at the inner portion 152, then there may be undesired stress around the holes 140 and the trailing edge spar connector member 130 may bend or even break. In one embodiment, the elevated surfaces 154 may be shaped to conform to (and avoid point contact and abrasion with) the insides of the composite aft spar tubes 106. In an alternative embodiment, soft spacers may be added between the elevated surfaces 154 and the insides of the composite aft spar tubes 106.

　　With respect to FIG. 6, the interface of the two trailing edge spars 106 as illustrated in FIG. 2 is enhanced and shown in transparency. The assembled trailing edge spar connector member 130 is shown locked into place within the two trailing edge spars 106; therefore, providing a secure connection between the adjacent, inner wing panels 102. More specifically, the trailing edge spar connector member 130 extends into each of the two trailing edge spars 106. Each clevis pin 132 spans the diameter of each of the two trailing edge spars 106. The annular head 137 of each bushing 132 seats flush on the outside of the aft side of a trailing edge spar 106, and the washer 144, secured in place by the cotter pin 146, seats flush on the outside of the forward side of the two trailing edge spar 106.

　　This embodiment is seen in further detail in FIG. 7 with a cross-sectional view of a trailing edge spar 106 with a trailing edge spar connector member 130 secured within. Again, the trailing edge spar connector member 130 extends into each of the two trailing edge spars 106. A clevis pin 132 spans the diameter of each of the two trailing edge spars 106. The annular head 137 of each bushing 132 seats flush on the outside of the aft side of a trailing edge spar 106, and the washer 144, secured in place by the cotter pin 146, seats flush on the outside of the forward side of the two trailing edge spar 106. This internal linkage provided by the trailing edge spar connector member 130 takes the tensile load across the two trailing edge spars 106, and secures the wing panels 102 to one another. The internal linkage takes axial tension. Axial compression may be taken by the aft spars 106 and the end ribs 104 butting up against one another. In one embodiment, the curvature of the internal linkage provided by the trailing edge spar connector member 130 is constructed to match the inside diameter of the trailing edge spar 106; therefore, when the internal linkage is pushed against the trailing edge spar 106, the internal linkage rests on the trailing edge spar 106 without digging into (and damaging) the trailing edge spar 106.

　　In one embodiment, each interface between adjacent inner wing panels 102 includes a trailing edge spar connector member 130. For example, the UAV 100 of FIG. 1 has 7 wing panels 102; 5 inner wing panels and two wing tip panels. Therefore, there may be 4 interface points between adjacent inner wing panels (see the red circles of FIG. 1), with a trailing edge spar connector member 130 at each interface. In one embodiment, the trailing edge spar connector members 130 may not be included at the interface between an inner wing panel and a wing tip panel, as the trailing edge spar of a wing tip panel connects to a trailing edge spar of an inner panel at an angle. In one embodiment, the loads are low enough at the outboard wing breaks (e.g., between an inner panel and a wing tip panel) that the trailing edge spar connection described throughout is not required. As described above, the shape of the main body 138 is necked down in the center where stress would otherwise be lower. This is done to bridge over a shim 149 in between adjacent wing panels.

　　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:
　　two or more wing panels, wherein each wing panel comprises:
　　a cross-bracing element;
　　an end rib, wherein the cross-bracing element is connected to the end rib; and
　　a trailing edge spar, wherein the end rib is connected to the trailing edge spar, and wherein the trailing edge spar is substantially hollow;
　　one or more trailing edge spar connector members configured to connect two adjacent wing panels of the two or more wing panels, wherein each trailing edge spar connector member comprises:
　　a main body comprising two or more holes;
　　two or more bushings for receiving two or more pins, wherein the two or more bushings hold the main body against a forward side of the trailing edge spars, wherein an end of each bushing seats against an aft face of the main body; and wherein the two or more pins pass through the bushings and hole of the main body.
　　The system of claim 1, wherein the trailing edge spar is made of carbon fiber.
　　The system of claim 1 or 2, wherein each trailing edge spar connector member fits inside the substantially hollow trailing edge spar of the two adjacent wing panels.
　　The system of any one of claims 1 to 3, wherein each trailing edge spar connector member transfer a tensile load across the two adjacent wing panels.
　　The system of any one of claims 1 to 4, wherein the pins are clevis pins.
　　The system of claim 5, wherein the clevis pins have a cylindrical body with a flat, circular head, and wherein a diameter of the head is slightly larger than a diameter of the body.
　　The system of claim 6, wherein the bushings are an annular cylinder with an inner diameter slightly larger than the diameter of the body of the pin.
　　The system of any one of claims 1 to 7, wherein the two or more pins extend out of the forward side of the main body.
　　The system of claim 8, wherein one or more cotter pins are placed through a hole at an end of each pin.
　　The system of any one of claims 1 to 9, wherein an inner portion of the main body is thinner than each end of the main body.
　　The system of any one of claims 1 to 10, wherein the forward side of the main body comprises one or more elevated surfaces with beveled edges that ramp down to an inner portion.
　　The system of claim 11, wherein the elevated surfaces are shaped to conform to an inside of each of the trailing edge spars.
　　The system of any one of claims 1 to 12, wherein the main body is made of titanium.
　　The system of any one of claims 1 to 13, wherein the two or more pins are made of titanium.
　　The system of any one of claims 1 to 14, wherein each bushing is made of at least one of: rubber, synthetic rubber, or polyurethane.
　　The system of any one of claims 1 to 15, wherein the bushings dampen the energy that is partially transmitted through the bushing.
　　The system of any one of claims 1 to 16, wherein the main body has curved sides around the holes.