John DeMar

January 2007


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EXAMPLE 1  -  Very Erosive

High solids, lots of metals and non-combustibles.  Aft grain has larger core, but not large enough!

Very close to popping the case.  This test was used to help design larger motors with this propellant.

6-grain 38mm Black Gold.




EXAMPLE 2 – Slightly Erosive

Not a long motor, but fast burn.  Curve simulated flat, but test shows slightly erosive at beginning.

This was used to help avoid erosive problems for larger motors with this propellant.

4-grain 38mm, 2-Blue.


EXAMPLE 3 – Not Erosive

Long motor, high burn-rate blue propellant, light metals.  Grains lengthened to reduce mass flux.

Also, aft two grains were larger core diameter.  Progressive burn as expected.

Tail from stepped grains, as expected.  Less average pressure, lower delivered Isp.

8-grain 54mm, 2-Blue.



EXAMPLE 4 - D-Grain, very mild erosive spike

83% Solids, 200/60u AP, medium burn rate.  “Ramp” in D-grain near nozzle to avoid larger spike.

Single 16” 54mm grain.