8 replies to this topic

[Dan]

i was searching the net today and i came across this rocket propelent formula. it is from http://krimzonpyro.c...ir/compoDB.html.

Rocket propellant #2
Source: rec.pyrotechnics
Comments: The propellant has a burn rate of 0.0385 inch/sec at 100psi and a burn rate of 0.04 inch/sec at 300psi. Burn temperature is approx. 1800K. and ISP=180.
Preparation:

Ammonium nitrate..................................85-90%
Elastomeric binder (HTPB or other urethane plastic).....?

i was thinking for the urathane plastic i could use gorilla glue of something of that nature. would i cast it in the tube first, let it dry, and than drill out the core? would it be a sensitive combination? also how much glue do i use?

thx for the help
Dan

[paul]

This propellant is by no mean usefull in pyrotechnics. Its way to slow and needs a very stable and good confinement. And the HTPB has to be of a special kind, I think. Nothing you would get in a hardware store.

Further on it needs an very big amount of heat to get it started. Have a look on Nakkas page for further details on compositions containing ammonium nitrate!

[Dan]

thx paul. i am glad i ask. saves me a whole lot of time.

BTW does anyone know a formula that i can just poor the propellent in and not have to ram it? maybe like an epoxy of some sort of glue?

Thx for the help.
Dan

[miniskinny]

Here's one that'd you just pour into your rocket and put the nozzle on after it dried:
Potassium nitrate.................................74.5
Sugar.............................................25.5
You'd put this, perhaps, on your stove burner, medium heat; when you see a carmel-ey substance on the bottom of your container on the stove, using an upward motion, move the melted substance to the top. Do this until the whole container is filled with a toffee-colored substanced. Pour this into a preferrabley cardboard rocket mold, and allow to cool. You can even put the nozzle on when it's not quite cooled down, this way you can stick the fuse in so it will be immobile.
This is a very common formula, so I don't know exactly who made it up, but I got it from
http://krimzonpyro.c...ir/compoDB.html.
-mini

[Dan]

thx miniskinny
when i try to make smoke balls with the same ingrediants the sugar tends to dry before it is all poored out. also with it drying so quickly wouldnt that couse air spaces in the propellent and possiblely making it cato. also could i drill out the core with a drill press (at the lowest speed ofcorse). also one other thing wouldnt ants be attracted to the sugar? i guess i will give it a shot though.

thx
Dan

[BigG]

Gentelment - please refer to Nakka's page for more information about candy propellents. The man done a lifetime of research on the subject, and I fail to see how we can add to that. On his pages is a compleate discussion of preperations, casing and additional valuable information.

http://www.nakka-rocketry.net/

[alany]

Yeah it is tough to keep candy 'pourable' long enough to cast into a good grain, especially if you are trying to get all the bubbles out. Having it slightly moist tends to keep it liquid a bit longer but decreases its performance quite a lot. You can (with practice) keep it plastic enough to press into a grain mold, even around a metal core to avoid having to drill it later, but it helps if the core is pre-warmed in the oven before use.

I used to use a toaster oven to soften up a lump of candy, press it into a cardboard tube, then shove the core down the middle and stick it in the fridge (in a plastic bag) to freeze completely solid quickly (Once frozen you can pull out the core pretty easily). It helps if your fingers don't feel pain! Or you have to wear a suitable pair of gloves, problem with wearing protective gloves is that you loose the touch and fine manapulation ability.

Don't get me wrong, touching the molten propellant will give you a very nasty burn, it sticks and keeps on burning, however it can be manapulated in the pseudoplastic state while cool enough to touch briefly. The mold also heats up and starts getting too hot to hold tightly for extended periods.

Sorbitol is interesting, it stays slushy even after cooling for quite some time, many hours. Sucrose exhibits the effect too somewhat, as does fructose and glucose, but with sorbitol it is quite pronounced.

When I still experimented with candy propellants I always added about 1% red Iron Oxide, it makes a big difference. But all in all I found sugar based propellants too hygroscopic and fiddly to work with.

[neo]

I tried that one today, but that was 60/40 mix so it didn't fly
Had a plastic tube and the funny thing is that it melted Anyone know why?
Is it that when it flies it gets cooled by the air?

[Stuart]

I cam across a very interesting webpage the other day about candy propellant. Instead of melting the Sucrose and Potassium Nitrate to get a good mix, he use's recrystallisation. Its quite simple and easy and makes propellant which becomes bendy when heated up and can be pressed into shapes and molds. The research isn't as extensive as Nakka's but it still has lots of very interesting information.

http://www.jamesyawn.com/

Stuart