Multi-segment spool release mechanism for spacecraft
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Solution Overview
Problem
Existing release devices for spacecraft elements, such as solar arrays, often experience unpredictable dynamics and friction-related failures due to the geometry and load distribution of two-piece split spool designs, leading to potential fouling and 'Friction lock up' conditions.
Innovation Solution
A multi-segment split spool with a central bore and overlappingly wound tensioned tape that prevents radial movement of spool segments, reducing friction and requiring less radial motion for release, while maintaining a low-profile design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-piece split spool design is used, then the device complexity is reduced, but the reliability deteriorates due to unpredictable dynamics and friction lock up conditions
Solution Approach 1:
The spool is divided into multiple segments (three or more) instead of using a two-piece design. This segmentation distributes the load and friction across multiple contact points, preventing the friction lock up condition that occurs in two-piece designs where the ball end contacts only two extreme points. The multiple segments provide more uniform load distribution and predictable unwinding dynamics.
2Ease of manufacture
If a wire wrapped around the spool is used to hold pieces together, then the ease of manufacture is improved, but the reliability worsens due to unpredictable dynamics and potential fouling upon release
Solution Approach 1:
A tensioned tape (flat flexible element) is used instead of a wire to hold the spool segments together. The flat tape provides predictable unwinding dynamics upon release because it maintains its shape and does not coil or foul upon itself like a wire would. The tape is tensioned to hold the segments together during stowage and releases cleanly to allow segment separation.
3Device complexity
If a two-piece spool design is used, then the device complexity is reduced, but the radial travel distance required for release increases
Solution Approach 1:
By dividing the spool into three or more segments instead of two, the radial travel distance required for release is reduced. Each segment moves a shorter radial distance to achieve the same release function, because the load is distributed across more segments and the angular separation between contact points is reduced.
4Reliability
If a multi-segment spool design is used, then the reliability is improved by reducing friction lock up, but the device complexity increases
Solution Approach 1:
The spool is segmented into three or more pieces to distribute friction loads and prevent friction lock up. This segmentation improves reliability by ensuring that the ball end of the captured member contacts multiple segments at more favorable angles (reducing the 180-degree separation issue in two-piece designs), thereby preventing friction-induced failure to release.
Data Source
AI summary
A release device having a multi-segment split spool with a central bore adapted to axially restrain a tensioned member. A tensioned tape is overlappingly wound around the spool segments thereby preventing radial movement of the spool segments. The overlapping winding allows for a low profile housing for the-release device. The multiple segments require less radial motion for release of the tensioned member.