Overview




Grain Geometry

  • Went with cylindrical geometry, less complex than booster motor 

Nozzle

  • Requirements 

    • Withstand 2*max operating pressure of the chamber

    • Attach securely to booster case

    • Support the fin can under high acceleration

    • Optimized for 14350 ft above ground level (sum of 2/3 of height difference from ignition to burnout and ignition

  • Materials 

    • Aluminum 6061-T6

    • Canvas phenolic

    • Graphite

  • For design procedure look here: Booster and Sustainer Nozzle Design

  • Decided to go with a concave convex nozzle rather than a bell nozzle like on the booster 

  • Two part phenolic seemed smart in design, but in practice was difficult to manufacture

  • When making the top phenolic ring I got chastised by Todd for a completely infeasible design (was somehow able to manufacture it but it was super sketch, just had to face 500thou )

  • In the future it would be much better to make the phenolic into one whole part rather than two pieces

Case

  • Requirements 

    • Withstand 960 PSI during burn

    • Withstand 1440 PSI for twice the burn time during hydrostatic test*

    • Utilize a FoS of 2*

  • Hoop Stress Approximation 

    • Used linearized formula

    • P = pressure

    • R = radius

    • t = case thickness


FRR, FC and Bolt Calcs 

  • If you care about this, you care more than me because I am too lazy to write it out; it is the same as what is described for the booster motor so you should look there 

  • Link: Booter Motor


Safety Margins



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