Phoenix Sustainer FRR
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Purpose
The forward retention ring serves 2 main purposes:
It retains the forward closure from sliding past the end of the motor casing.
It couples the motor casing to the airframe.
Requirements
Must withstand the force applied by the forward closure (4,330 lb)
Must be able to interface with motor casing (2.75”)
Must be able to interface with airframe (3”)
Design
In order to accomplish thisthe requirements, 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 inner cross-sectional area 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.
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