Low-cost rocket casing

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Re: Low-cost rocket casing

Postby SANEAlex » Fri Jul 18, 2014 9:19 am

rick m wrote:Just came across these old posts and they reminded me of the students in the afterschool rocketry club I used to have. I was sweeping autumn leaves from outside my door and one of my students said "Rocket fuel" and I said "Let's try it"

We let them thoroughly dry, crushed them, and then tried to grind it into a powder with mortar and pestle l (very hard to grind flexible flat things) and then soaked with super saturated solution of KNO3 for the oxidizer. The result? A very labor intensive low Isp propellant. After that experience, my students were always looking for new solid rocket fuels...cow dung, shavings from the pencil sharpener, etc.

Rick


Have you ever tried toner powder from a laser/photo copier cartage? I think it is mostly carbon black and as its very fine it might make a well mixed fuel IIRC gunpowder is more explosive as a fine mix maybe with pure KNO3 you could make a molar perfect firework rocket or do you think its likely to be actually explosive rather than the slow burn needed for a rocket.?
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Re: Low-cost rocket casing

Postby rick m » Sun Jul 20, 2014 4:55 pm

SANEAlex wrote:Have you ever tried toner powder from a laser/photo copier cartage? I think it is mostly carbon black and as its very fine it might make a well mixed fuel IIRC gunpowder is more explosive as a fine mix maybe with pure KNO3 you could make a molar perfect firework rocket or do you think its likely to be actually explosive rather than the slow burn needed for a rocket.?

Yikes, one of my favorites NOT to work with, the others are RIO (red iron oxide) and machining graphite...what a mess!

I do have to coffee grind or mortar and pestle charcoal when making our primer slurry for our sugar propellant. We have thought about using carbon black as an opacifier for our sugar propellant in less than 1% amounts but carbon is not an ingredient to our propellant (65/35 KNO3 to sugar).

You are correct about finely divided solids increasing the burn rate of the propellant. Scott Jolly micronizes his KNO3 that increases Isp slightly but makes it impossible to pour into the casting tubes because of the increased viscosity (it has a consistency of stiff mashed potatoes). To make it pourable, he then adds a surfactant that slightly decreases Isp.

To get the highest Isp but in a propellant that is still pourable for our purpose, we do a sieve analysis of our KNO3 before purchasing large quantities based on experimentation of what we require. We have a range of sizes that are acceptable and if a batch is slightly out of that range, some can be further ground or larger particle sizes added. Here is an analysis (we post everything, good or bad) of one such batch from a supplier we have used:
http://sugarshot.org/downloads/KNO3_KBH3_analysis.pdf

I recently helped with a 4th of July fireworks display (498 out of 500 mortars successfully fired and 100% of the cakes) for a local municipality and you are correct in saying finely ground will burn faster and make for great fireworks for some applications. Some of the effects require a slower burning powder and in rockets, you can adjust burn rate by the size but too fine and your pyrotechnics will simply blowup instantly. Someone once made up an igniter for us and I commented that it looked like finely ground 'firecracker powder'...the motor CATOed and we think the igniter was too powerful and cracked the bi-propellant grain we were experimenting with.

If you would like to try toner powder as the carbon source for rocket propellant I would certainly be interested in the results...after all, this is 'experimental rocketry' ( :

Rick
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Re: Low-cost rocket casing

Postby SANEAlex » Thu Jul 31, 2014 4:20 pm

I have only just noticed this and despite hopefully being unlikely to need that kind of propellent tho not a 100% certain yet as a solid rocket might make a good final stage under certain conditions I thought I look at the link from curiosity's sake but the direct link does not seem to work for me and then I tried the top level of the domain and that also does not seem to work so there might be a problem with your website as I seem to be able to reach others OK including this one.
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Re: Low-cost rocket casing

Postby Jay » Fri Aug 01, 2014 2:37 am

Just to confirm the observation, the page wouldn't open for me either. Other pages work just fine. Looks like the glitch is back in town!
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Re: Low-cost rocket casing

Postby SANEAlex » Thu Aug 14, 2014 10:04 am

To confirm Jay's observation in another thread the site is back up for me too and the direct link also works thanks.
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