Author Options:

help with black powder rocket Answered

hi i am making a black powder rocket similar to a bottle rocket just bigger scale and am having trouble with it ill give as much info as i hope someone can help me out thanx the rocket engine is 53 mm in length 1.5 mm thick wall 16 mm inside wall to wall hopefully that all sounds ok the (nozzle) in the end is 6mm thick was planing on filing it with black powder and packing it in around a core with 42 mm of powder and a further 5mm plug on the end then turn it over and put in a fuse etc... strap to a small stick or skewer and launch what i am wanting to know how big should the nozzle hole be to actually get lift off and should i just insert a fuse or a fuse and quick match or fill the core with loose black powder and make a paste of black powder and plug the end and insert a fuse onto that im probably going the complete wrong way about this if i am feel free to tell me what im doing wrong or what i need to do thanks


win you mix black powder damp it with 90 % alcohol this will make it so you do not lose a hand or kill your self and yes you can pack it with it damp but it takes a long time to dry out win pack in a tube but worth it works beter and the rockit form is the same as i use in my guns and cannon you just have to pack it right and use the right size nozzle for the load and i make this stuff a lot i make 8 to 50 lb at a time and i make test bach at 50cc i have made it useing outher i play with the mix a lot never ajust your potasium nitrate aka kno3 just your charcoal you can make it faster or slwoer by adding or takeing a way or useing outher charcoal a realy soffwood charcoal will burn fast a hardwood charcoal burn slow at less it works for me and i messt with the burn rate a lot i even have put outher stuff in my powders to make them explod or flash burn balsa wood charcoal makes black powder burn fast and light fast pine is harder to light and burn slow just make a small mix then add to it and play with your mix till you get one you like then rember what the mix is a good strting mix is the 75% potasium nitrate10%sulfer 15%charcoal do not for get dampin it a bit with alcohol i think it burns beter after doing this too

hi again thanks for all the info at the moment i think it could be a bit risky going so big so quick so im going back to the original ones i have made before


and ill try make them a bit more powerful once i perfect them i will slowly get a bit bigger sounds a bit safer to me lol
thanks again for all the help especially westfw


11 years ago

Your wall thickness is a little thin for a core-burning BP rocket. There are apparently standard diameters and wall thicknesses active since LONG ago (see Kentish), and Estes uses especially high-strength tubes and STILL has thicker walls than you mention for their 13mm ID motors. I guess you're doing the ramming with a hammer (which always made me really nervous), which SHOULD give you a solid enough BP slug to avoid the problems others are talking about, though achieving that gets harder as diameter increases. Kentish says the proportions stay constant. For a Bore of B, you want: External diameter 1.5*B Length 8*B Core Length 6*B Core Bottom 0.4*B (Nozzle exit diameter) And then you "adjust" the BP till the rockets fly without blowing up. If they blow up, add more charcoal. If they burn without flying, add more KNO3.

thanks very much for the info westfw will come in handy so this size rocket shouldn't explode if i follow the kentish info and make sure it is packed as tight as possible without blowing myself up thanks again ill let y'all know how it goes

At an event like Western Pyrotechnic Association's "Western Winter Blast", rocket makers with DECADES of experience have perhaps 10% of their rockets explode instead of fly. They have a big thick plywood "blast shield" that they duck behind when launching. With homemade black powder, you have added variables, and will have to adjust each "batch" of powder "just right" to get reliable operation. By following the Kentish recommendations, you'll be in a realm of dimensions that are known to work at least sometimes, a set of values where there is experience in the hobbyist fireworks community, and stuff like that. That doesn't mean the rockets won't blow up a lot, or that they'll fly well without a lot of "research."

I have convinced myself that the current interest level in non-BP rockets (candy, AP composites, etc) has as much to do with increased reproducability of results (ie by starting with surplus AP with graded particle size instead of "very fine KNO3") as it does with the increased performance over BP.


11 years ago

All I can suggest is a cell phone with 911 in speed dial!

ok ok u guys have realy lost me i have made these ones


thats the link to the black powder bottle rockets just smaller than i am wanting to make now i have gotten these to work just wanting to make them alot bigger ?
i cant see how it would explode unless the nozzle whole is too small ??
the black podwer i am using is made from an instructable also
75 15 10 of saltpeter coal sulfur
thje smaller ones work great was hoping on makeing them bigger to launch bigger payloads etc...
guess ill just have to stick to the small ones lol dont wana end up in hospital lmao
anyways thanks for the info so far

black powder rockets dont work because black powder burns way to quickly. try what i did:
Take a SOLID rocket, with NO powder in it... and no place for powder... and then get your self a tube that it will fit into...ram a black powder charge down teh tube.... followed by teh rocket... light the charge and BOOOMMNNNN!! explosion + flying rocket.
BE CAREFUL! this could actually kill you. Use a loong fuse. i make mine about 10 seconds long, makesure yout tube wont explode... i use PVC

Here is a vidoe of mine working.
youtube vidoe


Well heres some pictures of my next project. Those tubes are SOLID, they could hold the weight of a book or 2.

Smoke Bomb 019.jpgIMG_0006.JPGIMG_0007.JPG

I totally agree with Aeshir, black powder and anything else you would be able to lay your hands on would burn much to fast. Try taking apart a rocket engine, not only is the casing about five times thicker than yours, but you'll see the powder is one solid grain. This prevents it from flashing, it takes a while (about a second) to burn through the entire grain. Please don't try to make this, the amount of powder you would be using would be sufficient to fire a small cannon.


11 years ago

It won't work. Homer Hickam tried this, and it blew up in his face and sent his mom's fence flying into the air. The black powder just explodes (burns way too fast), and the energy can't escape out the nozzle fast enough. The energy that can't escape ends up pushing against the inside sides of the rocket and well.....BOOM! Try saltpeter.

Just please don't use black powder. It's VERY dangerous and it will only blow up.