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Our redesigned piston must have the same form factor as a McMaster piston to allow for easy descope. Given the team's Fall 2017 semester experience with tie-rod pistons, we elect to continue using this style.
DTEG Requirements
As of 1/4/2018, the latest edition of the Spaceport America Cup's Design Test and Evaluation Guide has the following requirements for SRAD pressure vessels. These requirements can be read in more detail here (add link).
4.2.2 DESIGNED BURST PRESSURE FOR METALLIC PRESSURE VESSELS
4.2.4.1 PROOF PRESSURE TESTING
4.2.4.2 OPTIONAL BURST PRESSURE TESTING
Desired Performance
The piston must be able to supply enough force at its operating pressure to break the shear pins with a 2x safety factor, which is the safety-critical guideline for parachute components presented by NASA (Section 3.3.1.5). The same source (Section 3.3.1.6) dictates a design burst pressure factor of 2x the maximum design pressure. [5] Then, to determine when the cylinder will burst, we make use of thin-walled pressure vessel theory [2], paraphrased below:
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