Ruggedized Reaction Wheel Assembly for Kinetic Launch Loads
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Solution Overview
Problem
Conventional reaction wheels in kinetically launched satellites fail due to extreme acceleration loads exceeding 5,000 times Earth's gravity, causing damage to bearings and shafts, which leads to inoperability post-launch.
Innovation Solution
A ruggedized reaction wheel assembly with a support device comprising springs and non-explosive release devices, such as shape memory alloy, that secures the wheel during launch to prevent spinning and transfers load to the satellite's primary structure, allowing the wheel to spin freely once the satellite reaches orbit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reaction wheel is designed to withstand extreme acceleration loads during kinetic launch, then the reliability of the reaction wheel is improved, but the device complexity increases due to additional support structures and release mechanisms
Solution Approach 1:
The support device is pre-positioned and pre-loaded during assembly, with springs already compressed and support blocks in place before launch. The release devices are pre-configured to automatically disengage at the appropriate moment, eliminating the need for complex real-time control systems during launch.
Solution Approach 2:
The support device acts as an intermediary between the reaction wheel and the satellite structure during launch. It temporarily bears the extreme acceleration loads and transfers them to the satellite's primary structure, protecting the sensitive reaction wheel components while maintaining a relatively simple design.
2Strength
If the reaction wheel is protected from extreme loading during launch using support blocks and springs, then the shaft and bearings are protected from damage, but the device complexity increases
Solution Approach 1:
Springs are pre-compressed between the support blocks and the reaction wheel housing to create a cushioning effect before launch. This elastic cushioning absorbs and distributes the extreme acceleration loads, protecting the shaft and bearings from direct impact and excessive forces during kinetic launch.
Solution Approach 2:
The support blocks are designed as temporary, single-use components that serve their protective function only during launch. After the satellite reaches orbit and the release devices disengage the support blocks, these components are discarded or remain stationary, while the reaction wheel continues its operational life without them.
3Ease of operation
If release devices are used to secure support blocks during launch and then release them post-launch, then the reaction wheel functionality is ensured, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The release devices utilize shape memory alloy (SMA) materials that automatically change their mechanical properties in response to temperature or stress changes. This replaces complex mechanical locking and unlocking mechanisms with a material-based automatic release system, reducing the number of moving parts and simplifying manufacturing while ensuring reliable operation.
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 solution effectively protects the shaft and bearings from excessive loading during launch, ensuring the reaction wheel's functionality and ability to control satellite attitude post-launch.
Implementation Method 1
The support device comprises one or more springs, a first end of one or more springs being attached to the wheel housing and a second end of the one or more springs being attached to the one or more support blocks, the one or more springs compressing when the one or more support blocks are placed between the wheel and the wheel housing.
Implementation Method 2
A ruggedized reaction wheel assembly with a support device comprising springs and non-explosive release devices, such as shape memory alloy, that secures the wheel during launch to prevent spinning
Data Source
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AI summary
Provided is a reaction wheel assembly ruggedized for use in kinetically launched satellites. An example reaction wheel assembly may include a shaft mounted to a body of a satellite, a wheel mounted to the shaft, wherein a center of a gravity of the wheel is co-aligned with the shaft, and a support device mounted to the body of the satellite. The reaction wheel assembly may include bearings for holding the shaft to the body of the satellite and allowing a rotation of the wheel. The support device can be engaged to support the wheel to reduce a load on the shaft and the bearing, the load being caused by an acceleration of the satellite during a kinetic launch of the satellite. After the satellite is launched into space, the support device can be disengaged from supporting the wheel to allow the wheel to spin.