7 replies to this topic

[vaslop2005]

Now heres a challenge to all the chemistry people out their. whilst looking at passfire, I saw a promising propellant that looked relatively simple.

1. Mix 70 parts ammonium perchlorate (200 micron), 17 parts triacetin (liquid plasticizer), 9 parts single-base smokeless powder, and 4 parts course charcoal or aluminum flitters in a plastic beaker.
2. Immediately pour the propellant slurry (before it thickens) into a rocket motor casing that is closed with a clay bulkhead on one end, and press the propellant slurry with a drift by hand. Insert a straw into the propellant at the end to form a cavity.
3. Wait for the plasticizer to dissolve the smokeless powder and form a gel.
4. Finish the motor by putting blackmatch (or a hotter pyrogen) in the staw cavity, and fusing and nosing.

I like the idea of a pourable composite, as it could eradicate voids and incomplete pressing that some formulas are sensitive to.

Now back to the question, does anyone know a source of this 'triacetin' or whether it can be made from esterification of glycerin with acetic acid, but still allowing for separation from the copious ammounts of water present (hopefully it isn't miscible)? I know that composite motors arent strictly used in pyro, but I'm planning on making some coloured tailed rockets that use a similar type of fuel for each colour, and that can be fully blended. (I believe AP to be the most promising oxidizer for this...) Also their is the problem with obtaining single base NC, but that will come later.

Thanks

[CCH Concepts]

i may be wrong, usually am, but isn't single base NC a HE like used in cordite?

[vaslop2005]

well, technically you are correct, but cordite and NC explosives are very insensitive, and are the modern replacement for gunpowder, and are only designed for deflagration. They can detonate also, but they are very stable (apart from the hexanitrate form, but this isn't what is required/wanted) and similar to ammonium nitrate in its sensitivity, in fact its sensitivity is dwarfed by the ammonium perchlorate in the same formula.

[CCH Concepts]

so theres not a risk of a cato having a HE components to it. i was just thinking if it blew on the ground, could the blast be enough to detonate the remaining NC and if it did how much worse would that be than say a whistle motor?

[vaslop2005]

I am open to being proven wrong, but I don't see a deflagration, in the style of a composite rocket fuel like this, having any way near the instability or speed or decomposition to cause a DDT (deflagration detonation transition) in full, you might see a very incomplete detonation, but this will only spread the rest of the fuel around the test site, not even burning, due to the large loss of pressure causing the flame front to become unstable (I have experienced this before, and it used under 0.1 grams of fuel, the rest being spread in my sand test box.) from what ive seen, a whistle rocket is still the most powerful CATO i have ever seen.

well actually, I once saw an idiot try and set off an ammonium nitrate rocket with a detonator, and that was incredibly loud...!

[CCH Concepts]

I'm not expert, i wouldn't know what would or wouldn't happen in this scenario. id be interested to see what some of the more experienced guys think.

but on a more constructive note, i defiantly like the idea of a pourable motor.

[Arthur Brown]

Triacetin is the tri acetic acid ester with Glycerol, and it is available as a plasticiser but 500G seems to cost 16.10 GBP, plus vat and carriage S24/25 :Avoid contact with skin and eyes applies.
Whether you can make it yourself depends on your organic chemistry skills, work out the reaction mechanism then determine the conditions, then source the acetic acid and glycerine (Which could raise eyebrows at any chemical sellers).

There are also other methods that would allow you to avoid the need for single base powder. Numerous propellant formulae exist that can be slowly poured then they harden.

Please do masses of documentary research before you make anything.

[vaslop2005]

I am just looking for a relatively simple, stable AP propellant that can be poured, I thought it was a lost cause untill I found this. Where is it that supplies triacetin? I'm guessing a lab supplier. Also would you be able to post any formulae of these other pourable propellants.

It is quite hard to find documentation regarding AP formula, or atleast I'm struggling.

Thanks V