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Overview

The HADES Cup transfers load from the piston and diaphragm to the booster section, breaking the shear pins and initiating the Recovery deployment sequence.

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Ground testing has shown that the cup does not buckle under normal piston operating loads, even those as high as 3500 lbs (an order of magnitude greater than normal operating loads) as we predict we saw in Ground Test November 10, 2017 Hermes Ground Test.

v2.0: Hermes Dimensions

Development

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Thickness (t)0.125"
Inner Radius (ri)2.675"
Outer Radius (ro)2.8"
Length15"
Useable Packing Volume~340 in3

Mass Saving Cut Options

Unknown User (ellenlee@mit.edu) Unknown User (amel@mit.edu) @Shannon Cassady

We ultimately chose to pursue the column design due largely to the simplicity of fabrication and decreased likelihood of line entrapment.

Optimized Cup Cuts for Column Design

Here are the spreadsheet calculations for the optimized cup cuts given the column design: Calculations for CADs (Cup and Diaphragm).xlsx

Ultimately, to increase the safety factor, we chose to increase reduce the cut width by a factor of 2. Simulation results are below.

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Resources

NASA, Buckling of Thin-Walled Circular Cylinders