15 replies to this topic

[Pieman]

I've just recieved my new tooling from Greg (see under the pyro tools -> rocket tooling thread) and really want to get onto making some rockets.
What formulae do people use when making BP rockets? I've got some good BP meal ready made and was thinking about slowing the mix down a bit with charcoal or a bit of atomised aluminium powder, at the moment I'd imagine it would just CATO.

[seymour]

Personally I would mill up (even using the chemicals in a coffee grinder then mixing is fine) Potassium nitrate, Charcoal and Sulphur in the ratios 6.3.1 or 65.25.10 and save your meal, but if you want to use it, I'd add 20% charcoal, and see how that works. everyones fuel is different, so if you want it faster or slower experiment.

[maxman]

What size core burner? A 1lb can use slower fuel than a 4oz. I use 70/30 and 80/20 respectively meal / charcoal

[Pieman]

Sorry I forgot to mention. I've got a 1 pound (3/4") and 8 ounce (1/2") rocket tooling set

[dr thrust]

hi pieman, it also depends on your tooling, if youve got a long spindle you need a slower fuel , like 65,kno3,25 lumpwood charcoal,10 sulphur ball milled for one hour and riced with 2% vaseline dissolved in thinners,(thanks jerronimo )to make a hotter fuel change the charcoal to willow. the riced bp is nice to work with,no dust just let it dry for a few days until the smell of thinners goes, also you can change the vasline for 3% baby oil which is a mineral oil, i'll try it myself at the weekend

Edited by chris m, 08 November 2007 - 07:47 PM.

[aquarius]

Chris M, please keep us posted on the "Baby Oil"- experiment. I guess you are trying it out as a binder and as a retardent?
I used linseed oil in my delay, and it worked ok, smelled a bit thought. And I am afraid properites will change when/if the oil dries out.
So I'll shift to Baby Oil and Sodium Bicarbonate to slow my delay mix down.

As for myself, I use a 70:20:10 mix, ball milled in a tumbler for 6 hrs, and added 3 % Red Gum. Wetted, riced and dried, moistened with 6 % alkohol and handrammed. A bit hot though, my drivers need a strong endplug. Ramming it wet works very well, almost no dust at all, but it needs to dry before it is used. I made my rockets for max performance with this 70:20:10 mix, and later added 10 % of fine charcoal for tail and ease of mind. Not all the same on the thrust side, but with lovely tails and less chance of blown endplugs or CATOs.

[maxman]

Sorry I forgot to mention. I've got a 1 pound (3/4") and 8 ounce (1/2") rocket tooling set

1/2" is 4oz 8oz is bigger i think about 14 or 15mm whatever that is in imperial. Please correct me if i'm wrong.

[dr thrust]

your correct according to weingart 4 oz is 1/2 of an inch and 8 oz is 5/8 of an inch, about 15mm .as for the babyoil bp so far so good,batched some last night its a lot easier than dissolving/ melting vaseline!, just waiting for the thinners to evap,also i did a quick "test" on a dry bit seems to burn faster and cleaner than the vaseline bp. chris

[marble]

Greg emailed me a good doc that covers the basics

http://www.warezwall...etromontano.doc

I use 60/30/10, ballmilled for 15mins with native hardwood charcoal.

Edited by marble, 10 November 2007 - 12:49 PM.

[dr thrust]

thanks for the link, marble, in the doc they talk about adding 5% mineral oil to the clay for the nozzle,i'll try that while ive got the baby oil out, i wouldn't mind trying some graphite , i wonder i could use a pencil?

[marble]

That would work fine I imagine, they do add clay to the graphite in the pencil though (I don't think that would make a difference)

[FrankRizzo]

thanks for the link, marble, in the doc they talk about adding 5% mineral oil to the clay for the nozzle,i'll try that while ive got the baby oil out, i wouldn't mind trying some graphite , i wonder i could use a pencil?

You sure could, though buying a big bottle of bulk graphite shouldn't cost more than £5. Just look at the local farm implement store...it's often sold as a lubricant for seed drills.

[dr thrust]

thanks for the graphite idea, i'll look into that, anyway just fired a couple 1lb,ers ten mins ago! both the same comp half with a vaseline binder and half with baby oil, the vaseline rocket had a thick orange tail and a good height, but the baby oil rocket launched well but disappointingly, ( to me anyway )there was hardly any tail just a few sparks it was hard to tell where it was in the sky! so it does work i guess, just not what i want! going to try a "visser" comp next 69,27,4,but vaseline riced

[icarus]

use really cheap supermarket barbecue charcoal lumpwood for slower bp+ i leave some coarser lumps in for a nice spark trail

[dr thrust]

hmmmm,the plot thickens!! whilst looking for graphite on the skylighter website there was a small explanation of its uses here it is. "graphite( and also lampblack) is used to opacify rocket fuel grains... the opacifier accelerates the rate of burning and prevents infrared enery from penetrating the propellent grain causing motor preignition.

so my question is ive never seen any comps with it in has anybody used it in rockets