Black Powder Rockets

[saluterocket]

Personally i prefer to use ball milled kitty litter, i have had succesfull results from 1/4 inch id rockets all the way to 1 lb'ers. I have launched many many rockets and have yet to have a nozzle failure.

[Pretty green flame]

I think end burners are more in danger of losing thrust than core burners, compare the burn time for example, core burners burn for a good 0.5sec-1sec when end burners burn for around 5second. And having hot gasses erode the nozzle for 5sec in an end burner you would definetly get a nozzle that has been enlarged ba a few %, and all end burners are very picky about nozzle size.

 

That's my thinking anyway.

[TheSidewinder]

PGF,

 

I've heard several people say that if erosion is a problem, substitute a few percent of graphite for bentonite in that formula I posted. I plan to try that next season. However, all the rockets I made with that original nozzle formula (at least SO FAR) have had no erosion that I could detect.

 

M

[Mumbles]

Not quite the same, but I made a fountain for thanksgiving that had very little errosion. BP based as well. I suppose it would be similar to an end burning rocket. It was straight benonite. There was some errosion noticeable . The inner walls of the nozzle were erroded smooth, but that was about the extent of it(nozzle was drilled).

 

I've heard that angling the interior of the nozzle helps to reduce errosion. It guides the hot gases out easier or something.

[psymon]

Personally i prefer to use ball milled kitty litter, i have had succesfull results from 1/4 inch id rockets all the way to 1 lb'ers. I have launched many many rockets and have yet to have a nozzle failure.

I used to ball mill cat litter until I found out that there is no need to. I have a sieve that I pass my cat litter through. The litter comes out with particles a little bigger than sugar grains. I use this for my nozzles and find that it works just as good as using powdered betonite clay. Try it, it saves so much time.

[Pretty green flame]

The initial results are in, the results are very disappointing, the silica sand/bentonite nozzle were inferior to the streight bentonite ones, in other words, they sucked big time.

 

It seems that the silica sand reduces the clumping properties of the bentonite reducing it into a useless powder and this was in any ratio i tried (30%, 15%, 10%, and 5%)

 

Stick with bentonit guys, silica sand is useless for everything except for makin glass and casting resin rams for BP dies.

[maximusg]

Here's a 1 lb BP core burner that i launched recently. Thers no delay as it was only an experimental rocket to test a new nozzle formula. But ye get the idea. Video is out of focus but the header was a 1" mgal can.

 

[Frozentech]

The initial results are in, the results are very disappointing, the silica sand/bentonite nozzle were inferior to the streight bentonite ones, in other words, they sucked big time.

 

It seems that the silica sand reduces the clumping properties of the bentonite reducing it into a useless powder and this was in any ratio i tried (30%, 15%, 10%, and 5%)

 

Stick with bentonit guys, silica sand is useless for everything except for makin glass and casting resin rams for BP dies.

PGF, you could make some Grog. Get one of those red clay flower pots ( or other cheap unglazed pottery ), crush it into 20 mesh grit. Add about 15% to your bentonite.

[maximusg]

Grog i great for rockets. I got some at a pottery place for 6 bux for 10lb

[Pretty green flame]

The initial results are in, the results are very disappointing, the silica sand/bentonite nozzle were inferior to the streight bentonite ones, in other words, they sucked big time.

 

It seems that the silica sand reduces the clumping properties of the bentonite reducing it into a useless powder and this was in any ratio i tried (30%, 15%, 10%, and 5%)

 

Stick with bentonit guys, silica sand is useless for everything except for makin glass and casting resin rams for BP dies.

PGF, you could make some Grog. Get one of those red clay flower pots ( or other cheap unglazed pottery ), crush it into 20 mesh grit. Add about 15% to your bentonite.

That's actually a very good idea, i'm going to try it first thing tommorow. Thanks for that.

 

Emm....one question though, do you have any experience with home made grog?

[Frozentech]

That's actually a very good idea, i'm going to try it first thing tommorow. Thanks for that.

 

Emm....one question though, do you have any experience with home made grog?

I tried it, and it works. I don't bother most of the time tho, I keep forgetting I have the grog made up. The theory is that the grog 'bites' into the tube wall and adds strength.

[Pretty green flame]

What's everyone's opinion on using motor oil (or lindseed) as an "compacter" in clay nozzles. I hear around 5% will greatly improve nozzle density.

 

What does everyone think about this?

[shadopyro]

Heh lol, i use a bit of linseed oil added to my kitty litter clay.

After blitzing to fine powder in the blender i add a small drizzel of it.

It makes the nozzles really smooth and doesnt break up easily.

It seems to work great for me asi havent had any catoes since i started using it, though maybe thats just an improvement in my technique...

[Pretty green flame]

Thanks for your help everyone, with your help i have made perfect nozzles. I've settled on the following formula.

 

90% Bentonite passed through a 30mesh screen and treated with 5% linseed oil

10% crushed up flower pots (GROG if you will) passed through a 20mesh and retained on a 30mesh screen (thanks for the suggestion Frozentech)

 

The nozzles are smooth, shiny, don't break up and don't erode, absolutely perfect.

[Mumbles]

Out of curiosity, do you let the linseed oil cure on the benonite before using it, or do you just mix it up batch by batch as you need it?

[Pretty green flame]

Out of curiosity, do you let the linseed oil cure on the benonite before using it, or do you just mix it up batch by batch as you need it?

Emm...i just mixed up a batch and used as is. To tell you the truth i have never before worked with linseed oil so i'm pretty much unexperienced with it. What does curing actually do?

[Mumbles]

Curing causes the linseed oil to polymerize into a plastic like substance. It was one of the very first plastics discovered. It's the reason when you coat Mg with it, you should leave it out for several weeks. There is a product called Japan Drier that is supposed to make it cure a lot faster. For it's normal use, who wants to wait for it to cure on woodworking for 3 weeks before applying another layer. Japan drier is a cobalt salt dissolved in petroleum distillates. I'm about 80% about cobalt, but if it isn't it's chromium. I believe that speeds it up to a few days.

 

Might want to do an experiment. Make up a batch. Press some rockets right away and shoot them. Leave the rest out in a thin layer for a month or so and press a few more, see if there is any difference. If a difference is noticed, you should do another test. Mix a new batch and make some more rockets. Shoot some right away, and shoot some a month later and see if the same difference is noticed.

[TheSidewinder]

To add to Mumbles post, for anyone interested:

 

Japan Drier is available in just about any Art Supply Store. It's used in Oil Painting to speed drying. (Oils take weeks or months to dry without it, days to weeks with it. Most people use Acrylics for that reason alone.)

 

I'm curious about this, as well. I have a hunch what the answer is, but I'll wait for results to see if I'm right.

 

M

[shadopyro]

Hm, that curing effect that you mentioned might explain a few things.

When i first tried using linseed, i didnt mix it that well.

After getting back from holiday (i just left it in an open baggie), when i finished ramming the nozzel, a piece of what seemed like rubbery bentonite peeled off...

[Pretty green flame]

Ok, i will try to find the curing agent for linseed oil and do a few tests as mumbles suggested.

 

One other possible application for linseed oil that crossed my mind was packing agent for the propellant grain. The idea is to make the grain more "crack resistant" by ramming to a greater density with the help of linseed oil. Although i ram my rockets hard there's always been that possibility of crackin during transport (bumpy road to launch site) and i have some recent CATO's under suspicion because of cracking. So i'm eager to try and eliminate that possibility.

 

Anyone got any info on this, personal experience?

[Pretty green flame]

Well, my firing site is not exactly round the house. It's a 15-20minute ride, by car, from my house. So please don't make dumb suggestion if you are not aware of the situation at hand.

[shadopyro]

I've had the same problem before with my larger rockets, as i have to mountain bike to my launch site - (very bumpy dirt path!).

I would guess that the addition of linseed oil would make it easier to remove from the drift, and in the case of my nozzeless rockets (which have been ruined a few times due to chipping of the BP), linseed oil will prob stop it from crumbling as much.

How much oil would you suggest adding to it?

[h0lx]

You could try adding dilute silicone or latex to the propellant, which makes it elastic and thus resistant to cracks. Just an idea, I wanted to share.

[Pretty green flame]

Holx, could be that it would work although my main concern would be drastic speed deterioration. I honestly don't know, i might try it someday though, just for the fun of it.

 

Shadopyro, well i have used 3% and the powder showed no visible signs or slower burning or more residue left (nozzle cloging), only a little is needed, i personally will stick to 3% for fuel and 5% for nozzles as this gave me the best performance so far.

 

Just as an interesting fact, i pressed an end plug (with linseed oil) under two tons and then tortured it with a flat head screw driver, i could barely scratch the surface, after a minute of turture the nozzle was in one piece with only a 5mm dent in the middle. This stuff is amazing.

[shadopyro]

Kk cool, think i'll start adding 3% to my fuel.

Cheers