8 replies to this topic

[PyroSkitz]

Hi Guys/Girls as ive seen on here recently.. just a quick question for people with far more knowledge than i have but i recently purchased a 3/4" gerb tooling stand, and ive made 3 beautiful gerbs so far which im rather happy with but the simple question is could the gerb tooling be also used to make a rocket using slowed down BP... (basically a tiger tail mix with added black powder for a bit more speed....)

any answers or information on this topic would be greatly appreciated

Thank you all
George

[PyroCreationZ]

I don't have experience with rockets (yet) but from what I know, rocket tools and gerb tools are the same so yep you should be able to make rockets with it.
Why would you use slowed down BP? You need fast BP for rockets, slow comp (i.e tigertail) for gerbs

Edited by PyroCreationZ, 28 August 2010 - 10:15 PM.

[seymour]

What are the specs for your gerb tooling?

I assume that it is going to make 'End burning' fountains, as in, there is NOT a deep core penetrating the composition grain.

If this assumption is indeed true, then the 'standard' fuel is straight black powder mill dust, straight from your barrel. Since the surface area that is burning is so small in this design, you need a very fast fuel. You can add a little Titanium or sparky Aluminium to give it a trail, but you probably don't want to add any charcoal to slow it down.

These normally have a nossle ID of about 1/4th the tube ID, though you should have some leniency.

[Arthur Brown]

To my knowledge gerb and rocket tools are similar but different. Rocket tools usually have a long spindle so that they burn on a larger flame front. People spend years optimising the design of their rocket spindle for the comp they wish to use, then they settle on a comp and spindle.

Yes the tool is similar but in a gerb the spindle is about the same length as the diameter as the tube bore, in a rocket the spindle is about 6 - 8 times the tube bore.

[seymour]

To my knowledge gerb and rocket tools are similar but different. Rocket tools usually have a long spindle so that they burn on a larger flame front. People spend years optimising the design of their rocket spindle for the comp they wish to use, then they settle on a comp and spindle.

Yes the tool is similar but in a gerb the spindle is about the same length as the diameter as the tube bore, in a rocket the spindle is about 6 - 8 times the tube bore.

That is all very true for Core Burning rockets, but certainly not End Burning rockets.

If it works will depend on the diameter of the spindle that forms the nossle. PyroSkitz, you are going to need to tell us what this is for us to be able to stop talking about 'What if" and just say 'yes' or 'no'.

[alany]

I made a gerb with stinger tooling once. Worked well, brief but very tall. Used Weingart cone composition.

[PyroSkitz]

wow thank you for all your information , and i dont have a veneer to measure the cores diameter or length, which is very frustrating... + you will probably reply to this saying your BP cant be that fast, but i am extremely worried about putting my milled BP in a rocket, wouldn't it just create a M80 basically ? + for effects i will add 250mesh magnalium, i will test one in the next few days and report back ASAP with video, but im glad i have a bit more information that i can trust a bit better than my previous judgment one last thing, is it does create a slight core, maybe 3/4 of an inch actually into the tube ?

[seymour]

250 mesh MgAl is a bit fine... surely that will just give you a white flame and no tail? It would certainly boost the BP's power though!

one last thing, is it does create a slight core, maybe 3/4 of an inch actually into the tube ?

Ok, we are definitely working with End-Burners then, so this means fast BP. BP too fast for rockets is not unheard of, but I think you should be fine, Especially with the smallish motors you are making. With larger rockets, things become a real pain.

Measurements need not be exact... Holding a ruler up to the spindle will allow you to give us measurements that would be useful.

If the nossle diameter is wider than a quarter of the tubes ID, then you may have issues with very poor flight, even though you are using fast BP.


As for loading straight BP, once you've rammed or pressed it in to the tube well, it becomes a single grain, and will behave much more 'tamely' than loose powder or grain. It still might 'cato', but that's part of the fun of learning to make rockets... there are so many variables that if you don't make a mistake somewhere, you are very unusual indeed.

My rockets probably went from 80% exploding, to 95% flying over several years...

Edited by seymour, 29 August 2010 - 10:59 PM.

[PyroSkitz]

ok, time to report back, made a rocket today, no measurements to be precise, just a tea spoon of magnalium to taste....sorry for not measuring it, but finding an exact formula would of just been annoying, anyways it worked fine, it had a header on it, with some silver streamer stars, lauched perfectly, but im guessing due to header weight/ stick length and other factors contributing to it, it veered off and went at a 45 degree arc, it was still a straight curve so it didnt wobble or anything like that, but i am happy with my first result , the video will be posted as soon as possible, due to HD camera / slow internet it might take some time