# US 10,767,682 B2 · Frangible fasteners with flexible connectors for unmanned aircraft, and associated systems and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,767,682 B2 - Document ID: US10767682B2 - Status: Granted - Kind: B2 - Application number: 15/638,137 - Filed: 2017-06-29 - Published: 2019-01-03 - Granted: 2020-09-08 - Earliest claimed: 2017-06-29 - Assignees: Insitu, Inc. - Applicants: Insitu, Inc. - Inventors: Michael Matthew Leon; Kristian Rubesh - Web page: https://patentgrep.com/patent/US10767682B2 ## CPC - F16B 31/021: {by means of a frangible part (F16B31/025, F16B31/028 take precedence; break members in torque limiters or torque indicators in wrenches or screwdrivers B25B23/1415)} - B64C 23/069: {using one or more wing tip airfoil devices, e.g. winglets, splines, wing tip fences or raked wingtips} - F16B 41/002: {Measures against loss of bolts, nuts or pins (devices for fastening nuts to surfaces F16B37/04)} - B64U 10/25: Fixed-wing aircraft (VTOL aircraft B64U10/20) - B64U 50/13: using external fans or propellers - F16B 2200/63: Frangible connections - F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D) - B64C: AEROPLANES; HELICOPTERS - B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR ## Abstract Frangible fasteners with flexible connectors for unmanned aircraft, and associated systems and methods are disclosed. A representative aircraft includes a fuselage portion, a wing portion, a winglet carried by the wing portion, and a frangible fastener coupling the winglet portion to the wing portion. The frangible fastener can include an outer body with a first portion in contact with the wing portion, a second portion in contact with the winglet portion, and a frangible portion between the first and second portions. A flexible member is positioned at least partially within the outer body and is connected to the first portion so as to extend through and out of the second portion. A stop element is carried by the flexible member. ## Claims ### Claim 1 An unmanned aircraft, comprising: a wing; a winglet carried by the wing; and a frangible fastener coupling the winglet to the wing, the frangible fastener including: an outer body having a first portion terminating at a first end of the outer body and in contact with the wing, a second portion terminating at a second end of the outer body opposite the first end of the outer body and in contact with the winglet, and a frangible portion located between the first and second portions, the first portion including a head integrally formed at the first end of the outer body, the second portion including external threads; a flexible member positioned at least partially within the outer body, the flexible member having a first end oriented toward the first end of the outer body, and a second end oriented toward the second end of the outer body, the first end of the flexible member fixedly connected to the first portion, the flexible member extending through the second portion such that the second end of the flexible member is located outside of the outer body; and a stop element fixedly connected to the second end of the flexible member and spaced apart from the second end of the outer body, the stop element being configured to contact the second end of the outer body when the second portion separates from the first portion in response to the frangible portion breaking. ### Claim 2 (depends on 1) The aircraft of claim 1, wherein the first portion is crimped to the flexible member. ### Claim 3 (depends on 1) The aircraft of claim 1, wherein the flexible member includes a cable. ### Claim 4 (depends on 1) The aircraft of claim 1, wherein the flexible member includes a solid wire. ### Claim 5 (depends on 1) The aircraft of claim 1, wherein the stop element is crimped to the flexible member. ### Claim 6 (depends on 1) The aircraft of claim 1, wherein the outer body has a hollow internal cavity with an opening located at the second end of the outer body, and wherein the flexible member includes a cable positioned within the hollow cavity, the cable extending through the opening and away from the second end of the outer body, the stop element having an outer diameter that is larger than an inner diameter of the opening. ### Claim 7 (depends on 6) The aircraft of claim 6, wherein the cable has an outer diameter that is less than the outer diameter of the stop element. ### Claim 8 (depends on 1) The aircraft of claim 1, wherein an outer diameter of the first portion is greater than an outer diameter of the frangible portion. ### Claim 9 (depends on 1) The aircraft of claim 1, wherein the winglet includes an internally threaded aperture, and wherein the external threads of the second portion of the frangible fastener are threadably received in the internally threaded aperture. ### Claim 10 (depends on 1) The aircraft of claim 1, wherein the second portion is configured to slide along the flexible member between the first portion and the stop element when the second portion is separated from the first portion in response to the frangible portion breaking. ### Claim 11 (depends on 1) The aircraft of claim 1, wherein the winglet includes an interior region, the second end of the flexible member being located within the interior region. ### Claim 12 (depends on 1) The aircraft of claim 1, wherein the winglet includes an internally threaded aperture, the external threads of the second portion of the frangible fastener being threadably received in the internally threaded aperture. ### Claim 13 (depends on 12) The aircraft of claim 12, wherein the winglet includes a nut plate located within an interior region of the winglet, the nut plate including the internally threaded aperture. ### Claim 14 A frangible fastener for coupling a first component to a second component, the frangible fastener comprising: an outer body having: a first portion terminating at a first end of the outer body, the first portion including a head integrally formed at the first end of the outer body and positionable to contact the first component; a second portion terminating at a second end of the outer body opposite the first end of the outer body, the second portion including external threads positionable to contact the second component; and a frangible portion located between the first and second portions; a flexible member positioned at least partially within the outer body, the flexible member having a first end oriented toward the first end of the outer body, and a second end oriented toward the second end of the outer body, the first end of the flexible member fixedly connected to the first portion, the flexible member extending through the second portion such that the second end of the flexible member is located outside of the outer body; and a stop element fixedly connected to the second end of the flexible member and spaced apart from the second end of the outer body, the stop element being configured to contact the second end of the outer body when the second portion separates from the first portion in response to the frangible portion breaking. ### Claim 15 (depends on 14) The frangible fastener of claim 14, wherein the first portion is crimped to the flexible member. ### Claim 16 (depends on 14) The frangible fastener of claim 14, wherein the flexible member includes a cable. ### Claim 17 (depends on 16) The frangible fastener of claim 16, wherein the stop element is crimped to the cable. ### Claim 18 (depends on 14) The frangible fastener of claim 14, wherein the outer body includes an opening through which the flexible member extends, and wherein the stop element includes a tapered portion configured to slideably enter the opening when the second portion separates from the first portion in response to the frangible portion breaking. ### Claim 19 (depends on 14) The frangible fastener of claim 14, wherein the outer body includes an opening through which the flexible member extends, and wherein the stop element includes a tapered edge configured to cut into the outer body around the opening when the second portion separates from the first portion in response to the frangible portion breaking. ### Claim 20 (depends on 14) The frangible fastener of claim 14, wherein the outer body includes an opening through which the flexible member extends, the opening having a key slot, and wherein the stop element includes a key positioned to slideably enter the key slot when the second portion separates from the first portion in response to the frangible portion breaking. ### Claim 21 (depends on 14) The frangible fastener of claim 14, wherein the outer body has a hollow internal cavity with an opening located at the second end of the outer body, and wherein the flexible member includes a cable positioned within the hollow cavity, the cable extending through the opening and away from the second end of the outer body, the stop element being having an outer diameter that is larger than an inner diameter of the opening. ### Claim 22 (depends on 14) The frangible fastener of claim 14, wherein an outer diameter of the first portion is greater than an outer diameter of the frangible portion. ### Claim 23 A method for manufacturing an unmanned aircraft, the method comprising: attaching a first component of the unmanned aircraft to a second component of the unmanned aircraft with a frangible fastener, the frangible fastener including: an outer body having a first portion terminating at a first end of the outer body, a second portion terminating at a second end of the outer body opposite the first end of the outer body, and a frangible portion located between the first and second portions, the first portion including a head integrally formed at the first end of the outer body, the second portion including external threads; a flexible member positioned at least partially within the outer body, the flexible member having a first end oriented toward the first end of the outer body, and a second end oriented toward the second end of the outer body, the first end of the flexible member fixedly connected to the first portion, the second end of the flexible member extending through the second portion such that the second end of the flexible member is located outside of the outer body; and a stop element fixedly connected to the second end of the flexible member and spaced apart from the second end of the outer body, the stop element being configured to contact the second end of the outer body when the second portion separates from the first portion in response to the frangible portion breaking; and wherein attaching the first aircraft component to the second aircraft component includes: threadably engaging the second portion of the outer body to the second aircraft component; and operably engaging the first portion of the outer body with the first aircraft component. ### Claim 24 (depends on 23) The method of claim 23, wherein threadably engaging the second portion of the outer body to the second aircraft component includes positioning the second end of the flexible member within an interior region of the second aircraft component. ### Claim 25 (depends on 23) The method of claim 23, wherein operably engaging the first portion of the outer body with the first aircraft component includes contacting the head of the first portion of the outer body with a surface of the first aircraft component. ### Claim 26 (depends on 23) The method of claim 23, wherein operably engaging the first portion of the outer body with the first aircraft component includes contacting the head of the first portion of the outer body with a washer, and contacting the washer with a surface of the first aircraft component. ### Claim 27 (depends on 23) The method of claim 23, wherein the first aircraft component includes an aircraft wing. ### Claim 28 (depends on 23) The method of claim 23, wherein the second aircraft component includes a winglet. ### Claim 29 A method for operating an unmanned aircraft, the method comprising: launching the unmanned aircraft, the unmanned aircraft having a first component and a second component connected to the first component with a frangible fastener, the frangible fastener including: an outer body having a first portion terminating at a first end of the outer body, a second portion terminating at a second end of the outer body opposite the first end of the outer body, and a frangible portion located between the first and second portions, the first portion including a head integrally formed at the first end of the outer body, the second portion including external threads, the first portion being operably engaged to the first component, the second portion being threadably engaged to the second component; a flexible member positioned at least partially within the outer body, the flexible member having a first end oriented toward the first end of the outer body, and a second end oriented toward the second end of the outer body, the first end of the flexible member fixedly connected to the first portion, the second end of the flexible member extending through the second portion such that the second end of the flexible member is located outside of the outer body; and a stop element fixedly connected to the second end of the flexible member and spaced apart from the second end of the outer body, the stop element being configured to contact the second end of the outer body when the second portion separates from the first portion in response to the frangible portion breaking; and placing a load on the unmanned aircraft, the load breaking the frangible portion, the first component remaining connected to the second component by the flexible member following the breaking of the frangible portion, the flexible member allowing movement of the first component relative to the second component following the breaking of the frangible portion, the movement being limited by the stop element. ### Claim 30 (depends on 29) The method of claim 29, wherein the stop element does not limit the movement of the first component relative to the second component prior to the breaking of the frangible portion. ### Claim 31 (depends on 29) The method of claim 29, wherein placing the load on the unmanned aircraft includes contacting the unmanned aircraft with a capture line, and releasably securing the unmanned aircraft to the capture line. ### Claim 32 (depends on 29) The method of claim 29, wherein the frangible fastener is a first frangible fastener, and wherein the method further comprises: detaching the second component from the first component by removing the first frangible fastener following the breaking of the frangible portion of the first frangible fastener; and re-attaching the second component to the first component with a second frangible fastener. ### Claim 33 (depends on 29) The method of claim 29, wherein the method further comprises removing the frangible fastener by: placing tension on the flexible member to draw the stop element into contact with the second end of the outer body; and rotating the first portion, while the flexible member is under tension, to unthread the second portion from the second component.