Frangible Winglet Fasteners With Flexible Tethers for UAV Impact Protection

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Solution Overview

Problem

Conventional frangible fasteners in unmanned aircraft often result in costly and time-consuming repairs due to complete detachment of expensive components during high-impact events, causing damage and breaking electrical connections.

Innovation Solution

A frangible fastener design featuring an outer body with a flexible member and a stop element, allowing the fastener to break at a specific point while maintaining connection through a flexible cable, preventing complete separation and allowing limited relative movement between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional frangible fasteners are used to secure aircraft components, then damage to components during high-impact events is minimized through complete separation, but electrical connections are completely broken requiring expensive and time-consuming repairs

Engineering Contradiction:

Improvedamage resistanceVSAvoidrepair cost and time

Core Design Contradiction:

StrengthVSEase of repair

Solution Approach 1:

The fastener is divided into a rigid outer body and a flexible member that can separate independently. The rigid outer body fractures to allow component separation and minimize damage, while the flexible member remains intact to maintain electrical connections, resolving the contradiction between damage resistance and ease of repair

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible member acts as an intermediary element between the rigid outer body and the aircraft components. It maintains the electrical connection while allowing the rigid outer body to fracture and separate, preventing complete connection failure and reducing repair requirements

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If frangible fasteners allow complete separation of components during operation, then component damage is reduced, but expensive delicate components may be seriously damaged or destroyed after detachment

Engineering Contradiction:

Improveimpact protectionVSAvoidcomponent integrity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The fastener system is segmented into a rigid outer body for structural load-bearing and a flexible member for maintaining connections. The rigid outer body is designed to fracture at a controlled location to absorb impact energy and protect components, while the flexible member maintains component attachment, resolving the contradiction between impact protection and component integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible member is pre-installed within the rigid outer body to provide a backup connection mechanism. When the rigid outer body fractures during impact, the flexible member continues to hold components together, preventing complete separation and protecting delicate components from damage

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If a rigid outer body is used in frangible fasteners, then structural strength is provided, but the fastener cannot accommodate relative movement between components without breaking electrical connections

Engineering Contradiction:

Improvestructural strengthVSAvoidmovement accommodation

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The fastener is segmented into a rigid outer body for structural strength and a flexible member for movement accommodation. The rigid outer body provides the necessary structural support, while the flexible member allows relative movement between components without breaking electrical connections

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible member is made from a flexible material that can bend and deform to accommodate relative movement between aircraft components. This flexible element maintains the electrical connection while allowing the necessary motion, resolving the contradiction between structural strength and adaptability

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design minimizes damage to aircraft components, maintains electrical connections, and facilitates easier removal and reattachment of components by using a flexible member that bends without breaking, reducing repair costs and time.

Implementation Method 1

a flexible member positioned at least partially within the outer body, connected to the first portion, and extending through and out of the second portion

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP3421362B1Frangible fasteners with flexible connectors for unmanned aircraft, and associated systems and methods

Publication Date: 2021.03.03 INSITU INC

Figure 1
Figure 2A
Figure 2B~2C

AI summary

Frangible fasteners with flexible connectors for unmanned aircraft, and associated systems and methods are disclosed. A representative aircraft includes a fuselage portion (101), a wing portion (170), a winglet (180) carried by the wing portion, and a frangible fastener (110) coupling the winglet portion to the wing portion. The frangible fastener (110) 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.