It seems that Strontium Carbonate-based red motors get a bit of a bad rap in the community. The king of these formulations is Pat Gordzelik’s Polish Rojo family of propellants. I originally shied away from making reds, as I believed PR/SPR to be “wimpy” propellants that made a weak red flame, and that real men used Strontium Nitrate to make red motors. But Strontium Nitrate has its problems — it’s highly hygroscopic and needs to be dried and screened before use, and the grains must be kept sealed tightly before flight. I have a few old Kosdon East “Red Rhino” motors that are nitrate based, and though they give a BRILLIANT red flame and a delightful low-thrust, long-burn profile, they are immensely difficult to light due to their age and the amount of moisture collected by the hydrophilic Nitrate groups.

So, I decided to try out Polish Rojo:

Nice flame, Pat! (Photo by SoCal Mad Matt, click for larger version)

Further details on the motor after the jump: This was a 54/1400 load in the venerable Arcas (flight #15, I believe) with something between Polish Rojo and Super Polish Rojo propellant. From my understanding, the only difference between the two is the size of the Magnesium used in the fuel; the Mag in this motor was -800 mesh stuff from Pat, though it was slightly clumpy, so I’m not actually sure what to call it. The motor used 3/4″ cores (since I didn’t have a 5/8″ drill bit with me at the launch to core the motor), so it was probably a very full J motor rather than the usual baby K we get from this case. But still, way cool flight.

Moral of the story: Carbonate reds are reds too!

Posted August 13, 2008 in Media, Propellant Formulation, Tests & Flights. Add Comment / Trackback