Stacked Spacecraft Hold-Down Release With Inertia Drum Cable Retraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current hold-down and release systems for stacked spacecraft generate debris, induce shock, and require complex actuation sequences, which are unsuitable for sensitive equipment and increase mass on the spacecraft.
Innovation Solution
A hold-down and release system using a cable relaxation and rolling assembly with an inertia drum, articulated lever, and actuator, which minimizes debris and shock by winding the cable onto the drum, reducing the need for additional hardware and simplifying actuation to a single actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tensioned bars are used for hold-down and release, then the spacecraft can be securely fixed during launch, but debris is generated and shock is emitted
Solution Approach 1:
The patent changes the physical state of the fastening element from rigid (bar) to flexible (cable), and introduces an inertia drum to control the cable's motion during release. This parameter change allows the cable to be wound onto the drum, eliminating debris generation and reducing shock emission while maintaining reliable spacecraft fixation during launch.
Solution Approach 2:
The patent converts the harmful shock generated by sudden tension reduction into a beneficial effect by using the inertia drum to control the cable's retraction. The drum's rotational inertia allows the cable to be wound onto it in a controlled manner, transforming the shock into a manageable mechanical process that secures the cable without generating debris.
2Reliability
If multiple actuators are used for actuation and release sequence, then controlled release can be achieved, but device complexity increases
Solution Approach 1:
The patent makes the single actuator multi-functional by connecting it to both the inertia drum and the articulated lever. The actuator serves multiple purposes: triggering the release mechanism, controlling the cable retraction, and managing the articulated lever's motion. This eliminates the need for separate actuators while maintaining controlled release capability.
Solution Approach 2:
The patent merges the functions of multiple actuators into a single actuator that controls both the inertia drum and the articulated lever. By combining these control functions into one actuator, the system achieves controlled release without increasing device complexity.
3Device complexity
If cable relaxation without rolling assembly is used, then release is simple, but shock is emitted and mass is not minimized
Solution Approach 1:
The inertia drum serves itself by using its own rotational inertia to control the cable retraction process. When the actuator triggers release, the drum's inertia allows it to rotate and wind the cable onto itself in a controlled manner, eliminating the need for additional shock absorption mechanisms and minimizing mass.
Solution Approach 2:
The patent introduces the inertia drum to change the parameter of cable motion from simple relaxation to controlled winding. This parameter change allows the cable to be systematically retracted onto the drum, reducing shock emission and minimizing the mass of the release system while maintaining simplicity.
4Reliability
If bars are ejected after use, then release is achieved, but space debris is generated
Solution Approach 1:
Instead of ejecting the cable after use (which would create debris), the patent recovers it by winding it onto the inertia drum. The cable is systematically retracted and stored on the drum, eliminating debris generation while maintaining the release function. The release mechanism is designed to achieve separation without discarding functional components into space.
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 system reduces leftover mass, eliminates debris, and significantly lowers shock, while requiring minimal energy and a single actuator for seamless release, enhancing spacecraft safety and efficiency.
Implementation Method 1
an inertia drum, an articulated lever configured for engagement and disengagement with the inertia drum at a first end of the articulated lever
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Hold-down and release system (10) for stacked spacecraft (7), configured to change from a hold-down position to a released position with respect to a launcher (13), that comprises at least one sub-system (20, 20'), each sub-system (20, 20') comprising: - a cable relaxation and rolling assembly configured to be attached to the launcher (13), comprising: - an inertia drum (2), - an articulated lever (3) configured for engagement and disengagement with the inertia drum (2) at a first end (11) of the articulated lever (3), - an actuator (4) connected to the inertia drum (2) and configured to trigger it, - a cable (5) comprising a first fitting (8), configured to engage with the articulated lever (3) at a second end (12) of the articulated lever (3), and having one of its ends connected to the inertia drum (2), such that the cable (5) can be wound on the inertia drum (2), and additionally comprising a second fitting (9) on the second end of the cable (5), and - a release mechanism (6), configured to be attached to one end of the outermost stacked spacecraft (1), and to hold the second fitting (9) placed on the second end of the cable (5) in the hold-down position, wherein in the hold-down position the articulated lever (3) is engaged with the inertia drum (2) and the first fitting (8) of the cable (5), and the cable (5) is tensioned between the first fitting (8) and the second fitting (9) to keep the stacked spacecraft (7) together, and in the release position the articulated lever (3) is disengaged with the inertia drum (2) and the first fitting (8) of the cable (5).