Multi-Grommet Retained Slider for Parachute Reefing
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Solution Overview
Problem
Existing parachute reefing systems fail to effectively delay the opening of large ram-air canopies and manage suspension lines, especially under heavy payloads, leading to sudden shock and potential line tangling issues during deployment.
Innovation Solution
A rectangular slider type reefing device is physically secured to the ram-air canopy with multiple grommets and retaining devices, featuring breakable fastening elements that vary in strength along the canopy to ensure a controlled and delayed descent, managing suspension lines and regulating canopy inflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a flow deflecting flap is used to delay canopy opening, then aerodynamic delay is achieved, but under heavy loading the slider descends too rapidly and adequate retarding is not achieved
Solution Approach 1:
The retention system is segmented into multiple breakable fastening elements distributed at different locations along the canopy suspension lines. Each fastening element can break independently based on local force conditions, allowing the system to adapt to varying load distributions and provide reliable retention even under heavy payloads.
Solution Approach 2:
Different breakable fastening elements are positioned at different locations along the suspension lines, with each element having properties optimized for its specific location. This allows the retention system to provide locally appropriate resistance to slider descent, with stronger retention where needed and weaker retention where less force is required.
2Reliability
If pyrotechnic connections are used to release canopy sections, then heavy payload deployment is achieved, but the system becomes highly complex and very expensive
Solution Approach 1:
The breakable fastening elements are designed as simple, inexpensive, single-use components that break when their retention function is no longer needed. These disposable fasteners eliminate the need for complex pyrotechnic systems while providing reliable heavy payload deployment capability. The simplicity of the fastening elements makes the overall system cost-effective and suitable for routine operations.
3Ease of operation
If a slider is not physically connected to the canopy, then the slider can move freely, but the flow deflecting flap is insufficient to withstand air flow forces under heavy loading
Solution Approach 1:
The breakable fastening elements are pre-installed to provide preliminary retention of the slider to the canopy before deployment. This preliminary connection ensures that the flow deflecting flap is properly positioned and can effectively withstand air flow forces during the critical initial deployment phase, while still allowing the slider to move freely once the fasteners break.
Data Source
AI summary
A reefing slider for providing improved line management and canopy deployment characteristics of a ram air inflated airfoil type canopy. During initial descent of the parachute the slider, secured by retaining elements, is held against the canopy in the upper reefing position where it mechanically restricts canopy deployment while giving the canopy time to achieve proper orientation following the drop from the launching aircraft. Upon sufficient air flow into the canopy cells, the retaining elements separate, releasing the slider and enabling full opening of the canopy.