Phoenix Sustainer FRR
Design
The forward retention ring serves 2 main purposes:
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In order to accomplish this, certain design considerations were made. The forward closure presses upward on the aft end of the FRR. The force it applies is equal to the chamber pressure times the ID of the motor casing. The FRR must be able to withstand the load of the peak pressure (given by the Propulsion Sub-team) with a safety factor of 2. Working with Propulsion, we decided that the FRR will have 1 row of 12 ¼-20 holes that interface with the motor casing. This was based on calculations that Prop did for the motor casing.
The FRR was designed to be made from 6061 T6 aluminum. This makes the part affordable and easy to machine. Later designs may be able to be made from 7075 alloy aluminum, which has a higher yield strength and a higher cost. Using 7075 could allow for a more lightweight design, saving weight on one of the heavier parts of the rocket.
Using FEA, I decided that this cross section worked under the following conditions:
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