How to keep my BP fountain from becoming a salute?

[stug161]

I enjoy making some small simple fountains for backyard fun. Just a basic comp of KNO3 24, Sulfur 4, Charcoal 4, and cast iron turnings 10 (FROM AN ENGINE BORING BAR!! ) It provides for a quick easy mix with nice results. I hand ram it in 5/8 ID tubes 3 1/2 long with a bentonite nozzle. The first few I made had no nozzle and it just burned of course. Then I tried a 7/16 hole and it provided a good display with lots of sparks. Then I went to a 3/8 hole. That made it much better! Probably 10 foot length fountain with lots of noise and plenty of show! How small can I make my nozzle to get even more distance/height? Will the thickness of the nozzle itself change the pattern? It sounds like a rocket engine now, which is ok, but I sure dont want it to ka-boom on me! Also, any good suggestion on slowing the burn down? It seems to go through the whole 3 inches in about 4 seconds. Maybe just add more metal?

 

 

Thanks, Robert

[andyboy]

More metal, different ratios of chems, larger particle-size, using an inhibitor (flour, wood meal, betonite etc). Hope that helps

[Miech]

If it sounds like a rocket engine I'd go for a different formula. Try Chrysanthemum #8 as base mix, and add about 10% by weight of metal. A nozzle of about one third of the tube ID works for me, but you might want to make it smaller or larger. When ramming about 5 inches of composition in a tube you should get about 30 seconds of burn time. Beware, cast iron is cited to be prone to sparking when rammed, so pressing is preferred instead. Coat your iron with linseed oil if you plan on storing your fountains.

 

If you want them to spit higher, you could also try Chrysanthemum #6, it's more oxygen balanced and burns faster. For slower and more discrete burning fountains try tiger tail as base mix. Don't go over 20% of metal, it will clog up your nozzle and introduce a risk of explosion.

[Seymour]

To answer your question about nossle thickness, increasing it will to an extent increase the height of the spray, and to slightly greater extent increase the chances of a boom.

[Twotails]

Now, you guys are talking about (clay) nozzles for BP fountins, what about useing the crimped paper method? i know it wont last as long, and sometimes special tooling is required, but would that work also(to an extent?)

[Mumbles]

If you have a core burner rocket tooling, you have all the special tooling you need. I don't see why it wouldn't work. I've seen another method of crimping, but I don't know many details.