gdeputy Posted June 6, 2014 Posted June 6, 2014 Got around to trying out making a BP rocket motor for the first time today. Did an 8oz using tooling I made based on dimensions from the Rocket tooling sketcher. Tested the motor in the ground, nozzle up. The motor lit, burned pretty vigorously, almost too vigorously, then chuffed out. It then started back up and burned less vigorously for a second or so. I'm thinking the motor chuffed out when the core finished burning and was left with only the delay column, then managed to start back up until that was gone. Sound reasonable? Fuel is 60 - 30 - 10 hand screened BP. KNO3 was milled in a coffee grinder, everything screened together and hand mixed, no ball milling involved. After use, the nozzle is still intact, etc. Sorry for the crappy cell-phone video... http://youtu.be/t-zq-wGGjDE
dagabu Posted June 6, 2014 Posted June 6, 2014 Great job on your first BP rocket motor, it didn't chuff, that was the end of the core burn, the delay was next and by the time it burned through the delay, there was a doughnut of powder left which increased the surface and looked like it was "going again". Could you please put a stick on that thing so we all can go, Ohhhh, Awww, OOOOhh! 1
gdeputy Posted June 6, 2014 Author Posted June 6, 2014 Thanks for the feedback, #2 will be pointed the right way (up). How big of a heading can an 8oz rocket generally lift?
dagabu Posted June 6, 2014 Posted June 6, 2014 Thanks for the feedback, #2 will be pointed the right way (up). How big of a heading can an 8oz rocket generally lift? Start with a festival ball and go from there. You really need to get a test stand to measure the thrust, if you get the ACME from Peret, it comes with some nifty software that will give you weight and shell shape lift heights. Of course, the delay will ultimately determine the location the shell bursts.
nater Posted June 6, 2014 Posted June 6, 2014 A festival ball is a good start as Dag mentioned. I also like to make simple bag shell headers. Wrap a few turns of recyled kraft around the end of the tube with about an inch pasted to the outside of the tube and a few inches exposed to make an empty bag. Dump a teaspoon or two of your granulated BP fuel or favorite burst in the bottom and load with stars, leaving enough room to close the bag with a triangle fold or bunched up and tied like a bucket. Add more granulated fuel or BP to fill the spaces inbetween the stars and then close the bag. Now you are ready to fire. The effect will be like a mine in the sky, a very traditional header for a BP rocket.
gdeputy Posted June 9, 2014 Author Posted June 9, 2014 Made some festival ball sized can shells and tested one on top of a rocket last night, worked great! Thanks again for the help. Will get video on the next one.
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