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Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: Ragnarok » Sun Feb 10, 2008 7:02 am

Actually, this is quite an old idea, I remember it from back about a year and a half back. There was a thread on UKSGC, and I'm sure there's a thread on spudfiles... here!

Most of the maths has already been done for you. In terms of energy, it's going to give off 6% more than propane in the same volume of chamber, and it also burns cooler so less heat is lost. In theory, it could yield quite a lot of power.

For a 3 litre chamber, it's just 0.5cc of sugar for the right ratio assuming total burn. In reality, you might need a little more to compensate.
However, the main problem is keeping the fuel suspended, but I think if you used a modified jet ignition to blast the powder into the air and simultaneously light it it might work.
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Unread postAuthor: jimmy101 » Sun Feb 10, 2008 11:03 am

The tricky thing about a dust explosion is getting it to work! Dust explosions are really finicky when it comes to the conditions.

You need just the right particle size. Something like table sugar is much to coarse to reliably ignite. Powedered sugar is closer to what you want.

You have to get the fuel well distributed and suspended in the air. Humidity has a large affect on getting the fuel suspended properly.

A high speed fan in the chamber should be able to suspend the fuel, a jet ignition system might be a bit'o overkill.
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Unread postAuthor: Ragnarok » Sun Feb 10, 2008 2:51 pm

Icing sugar might work. That's about as fine as it gets in sugar terms, and it will quite easily become airborne - if you've ever tried pouring it from a large height, a lot will drift across rather than down.

Jet ignition may be too much - but my experience with these things says that most of the time you need a flame to light suspended powders, because sparks don't have enough energy in them for igniting a powder.
However, a flyback transformer would certainly provide a reliable ignition source.

Whether a stungun would do the job - I'm doubtful. I've spent enough time burning stuff with mates that I've picked up how sensitive airborne dust is to particle density when you're trying to light it. Eventually we realised that when we were sprinkling the milk powder everywhere, we had to do it about 18" to 2' above the flame. Too low, the dust was too dense. Too high, it was too sparse.

However, when it was done right, you got these wonderful flames that chased up the column of dust, as the heat from the flames helped separate the dust above it.
Wonderful orange flames.
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Unread postAuthor: jackssmirkingrevenge » Sun Feb 10, 2008 11:16 pm

jimmy101 wrote:The tricky thing about a dust explosion is getting it to work! Dust explosions are really finicky when it comes to the conditions.


It makes the poeple who are actually killed and injured in them really out of luck then :?
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Unread postAuthor: jimmy101 » Mon Feb 11, 2008 3:58 pm

jackssmirkingrevenge wrote:
jimmy101 wrote:The tricky thing about a dust explosion is getting it to work! Dust explosions are really finicky when it comes to the conditions.


It makes the poeple who are actually killed and injured in them really out of luck then :?

Yep. Grain silos are/were notorious for dust explosions. But even in the days before regulations meant to minimize the hazard, dust explosions were still pretty rare. A silo could be used for decades then suddenly decide to blowup. Like I said, the conditions have to be just right. The temperature, humidity, percentage fill, and of course, you need a suitable ignition source.
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Unread postAuthor: OuchProgramme » Mon Feb 11, 2008 8:42 pm

Well if 6 people had died and the fire is still raging on...

I'd think it would be perfect. Stay behind bullet proof windowssss
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