3 replies to this topic

[felixthecat]

i while ago i mixed 200g of 6 3 1 bp and rammed four 3/4 coreburner rockets,,the kno3 was from a ebay( and was sold as pyro grade) instead of my usual supplier,,,when i tested a motor it failed to develop enough thrust to fly and instead was like an upside down charcoal fountain,,a second test was identical...so i had 2 charcoal fountains left,i decided to see what  would happen if i filled the hollow core with coarse mgal and al flitters...the result was a pleasing fountain with a strange pulsing effect, 5 times during the burn(which was longer than a similar sized solid core fountain) the fountain died to almost nothing then burst back into life in a large mushroom shaped pulse that looked really good,,im going to do the same with the other motor and hope to repeat this. if it works im going to try ramming my usual fountain mix using my coreburner tooling and see if i can repeat the results...does anyone have any ideas about the mechanisim behind this `pulsing` effect

[megabusa]

Most likely due to the effect of slag clogging the nozzle.

Every so often the pressure increases as the blockage builds up to a point where the pressure clears the blockage with a surge in the plume effect.

[Sparky]

Yep I had this problem when making a gold glitter fountain composition. It was very slow burning and drossy, the slag would form a partial plug and the increased pressure inside would improve the reaction speed enough to "cough" it out. It's simply a factor of the poor BP you've rammed into the tubes. I had to mill my BP a little to get the reaction a little more vigorous and remove the pulsing.

[felixthecat]

thanks for your input guys,,,the second test was identical and i intend to see if i can replicate the results with 55/35/10 with kno3 i know is good,,,,sorry for the delay in replying,,,things are rather hectic at the moment