Overview:

The booster case is what surrounds the actual liner and solid fuel, and can be thought of as the foundation for the motor. Its purpose is to hold the hot gasses from the fuel's combustion without bursting or melting, and to serve as a shell for other components to attach to. It consists of a single aluminum tube with holes for bolts.

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To see calculations for the shear stress on the forward closure bolts, see Rocket Team Bolt Specifications.

Manufacturing:

 The case starts off as a long aluminum tube. To finish it, first cut the tube down to the appropriate length, and then drill the bolt holes.