248 replies to this topic

[aquarius]

Haha! So Mr. Confuzius is present!

For clarification: I am aware of "slow" charcoal, and that was actually my point, as a note to self: Use faster BP, if it does not work, use a smaller nozzle.
I don't think I will mess around with my fuel, once I have a standard fuel locked in, I find it easier to work on the tooling. That might be because I own a lathe...

As for me, I suspect using my standard tooling with a 5 mm nozzle on a 15 mm ID is too big for a end burner on 70:20:10 BP.
Once I get some more time on my hands, I'll turn out a few more tools and make the nozzle smaller, I'll try 4 mm.

I like to regulate the nozzle diameter or spindle length, as opposed to having 19 different fuels lying around for spesific drivers...

[Pyromaster2003]

Do you mind sharing those test vids cplmac?

aquarius, with out a doubt the nozzle is too big for the propellant you are using. Each to their own but i like experimenting with difference comps and design specs for rockets so you can produce different effects and results. With end burners theres no need for the hassle of turning out rocket spindles just drill the clay nozzle carefully until you reach the propellant, then all you do is change the drill bit around to change choke diam.

Been making some powerful end burning rockets the last couple of days, one was made with this spec and in this order:

3/4 inch ID tube, 5 inch long
3/4 inch long clay nozzle with 3 mm choke
2-1/4 inch long propallant grain (50/50 willow meal/green mix with 3-5% 250 mesh Spherical Al)
3/8th inch hard rammed clay plug
Ti flash poured to within 1/2 inch from open end
3/8th toilet paper rammed puck pushed in so it was flush with tube end and secured/strengthend with strips of gaffa/duct tape.

Pics and vid:

www.pyrotubes4europe.com/pyropics.html

Vid was took off my phone so quality is sh*te but if you look close you can see how high up the smoke from the salute is, went about 200 feet in no time!

[cplmac]

3" salute with Ti whistle spolette

My first salute shell, also 3" no tail (first one, didn't know any better)

2.5" Whistle ball salute

2.5" Red Flash Salute, different camera, so volume is lower

I haven't done a salute in awhile. I spent a couple of months trying to dial in red flash, but I think I have it about as good as I'm gonna get it. I have lots of rocket videos which would be more appropriate for this thread. Here is one from two weeks ago:

3lb Glitter Rocket to Report

Edited by cplmac, 24 March 2007 - 12:03 AM.

[Pyromaster2003]

Good stuff i like a big chest thumping aerial maroon and that rocket was spot on

[aquarius]

Tried a new tooling I made today, a endburner with 15 mm ID and 3 mm nozzle.

Three different fuels; 70:20:10, same with 10 % C added and a fast 75:15:10 BP with homemade charcoal.
With the two slower the driver lifted, but not sufficient thrust to lift anything serious.
The one with fast BP went up a few meters and then went bang..

Are endburners that hard to get right?
I might try to make the choke section longer, to create more pressure with the slower fuels.
Back to the ramming station..

[BrightStar]

Are endburners that hard to get right?

Yes, unfortunately

Best to work in the summer, when at least you'll get some sunshine and fresh air with test after test after test...

From my notes:

12mm * 80mm end burning rockets, approx 8g charge... a) 75-15-10 + 5 Al willow with 3mm nozzle - instant CATO, 75-15-10 +5 Al willow with 3.5mm nozzle - delayed CATO several metres off the ground - suspect uneven ramming of comp, c) 75-15-10 +5 Al with garden charcoal, 3.5mm nozzle, essentially a smoke charge!, d) RHP formula with willow, dry meal, 3.5mm nozzle, 1cm core depth, success but still too slow...

Edited by BrightStar, 04 April 2007 - 06:18 PM.

[Wyvern]

I have just bought some Molochite in order to try and make my rocket nozzles a littlr bit more fire resistant and also hopefully considerably stronger, has anyone experimented with this before and could point me to a good molochite:bentonite ratio otherwise i shall just experiment and post the results.

[Pyromaster2003]

I know this isnt any help with your question but whats wrong wih cat litter clay? I use it straight from the back in little rocks and this really grips into the tube when rammed hard and the choke doesnt degrade at all, maybe it does a tiny bit but its not noticable. Iv notice if you ram powdered cat litter you end up with a cato when making end burners, or core burners for that matter, but when just ramming it straight from the bag in rock form its very strong.

[Wyvern]

I know this isnt any help with your question but whats wrong wih cat litter clay? I use it straight from the back in little rocks and this really grips into the tube when rammed hard and the choke doesnt degrade at all, maybe it does a tiny bit but its not noticable. Iv notice if you ram powdered cat litter you end up with a cato when making end burners, or core burners for that matter, but when just ramming it straight from the bag in rock form its very strong.

hmm thats interesting, it must just be the clay i have, when i inspect the remains of my rockets i always find that the nozzle hole is about twice the size than when i rammed it.

[pudi.dk]

I also use the pellets as they are, except I turn them in a small amount of waterglass to make it more fireresistant.

[BrightStar]

Iv notice if you ram powdered cat litter you end up with a cato when making end burners, or core burners for that matter, but when just ramming it straight from the bag in rock form its very strong.

I noticed this too - ball milling or grinding cat litter seems to make it much weaker than fresh stuff out of the bag. It seems to be a mixture of bentonite, sand, organic fillers and wax and these appear to separate during the milling process.

Wyvern - my most successful mix so far is: 10 parts sandy cat litter, 10 parts bentonite, 2 parts graphite, 1 part wax. I haven't really done any proper tests to optimise it or tried grog (or Molochite) yet, so I guess you'll have to play it by ear... maybe 1/3 or so of the total? There used to be some nozzle mixes on pyrotooling.com, maybe they will be restored when the site is rebuilt.

[Pyromaster2003]

Could be the clay or could be how hard you ram it? i really hammer this in with 5-6 very hard blows. Then again it could be a very hot comp your using - i normally use meal/green mix and ti/al for propellant in end burners...adding waterglass sounds like a good way to make it even more resistant to degrading good idea.

[Wyvern]

I dont think its lack of ramming, i realy give the clay a beating with a wooden mallet i use bentonite from a pottery supplier so its possible that kitty litter has other ingredients it which help with its fire resistance

[Pyromaster2003]

That will be it then.

All this talk about rockets got me thinking about making a couple tomorrow might go for a big 3lber if i can be bothered driving half hour out of town!

[pyrotrev]

I suspect the reason "raw" kitty litter is stronger is due to the structure of some of the minerals in it, maybe some type of clay that has relatively large crystals. Milling it down destroys these and reduces the ability of the stuff to hold together - finer is not always better.