After consulting with a few of my more-experienced propellant-head friends, I’ve come up with a formula that should give me a decent purple flame color.  Hence, “Putative Purple Propellant”.

I mixed up a 300g batch Sunday, and cast some in 29mm and 38mm sizes for preliminary testing.  Once they’ve had a few days to ensure that they’re completely cured, I’ll cut them into grains, and drill the cores to give me a relatively neutral “BATES” grain burn profile.  I’ll do my initial testing at a fairly conservative Kn ratio, as I’m not interested in absolute performance numbers, yet — which is good, since I haven’t built a test stand for data capture, yet.

Instead, I’m mainly looking to get a good purple flame color and a smooth burn.

For the record, here’s the formula for Putative Purple v1.0:

  • AP200 (60%)
  • AP90 (10%)
  • Sr(NO3)2 (9%)
  • Mg (3%)
  • CuO (2%)
  • Tepanol (0.3%)
  • DOA (3.4%)
  • HTPB R45-HTLO (10.6%)
  • E744 (1.7%)

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