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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: Technician1002 » Fri May 29, 2009 11:16 am

Mongloid wrote:You must have put a fan in it.


If it is perfectly mixed on delivery to the chamber, there should be no reason for a fan. It's already mixed.
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Unread postAuthor: chenslee » Fri May 29, 2009 11:53 am

Here is the simplified diagram. No metering, no fan, no air pump. Just Propane and a valve. I had it shooting very consistent, powerful and fast last night.

STFU ABOUT THE FAN. There is plenty of air/wind in there.

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Unread postAuthor: Technician1002 » Fri May 29, 2009 12:04 pm

chenslee wrote:Here is the simplified diagram. No metering, no fan, no air pump. Just Propane and a valve. I had it shooting very consistent, powerful and fast last night.

STFU ABOUT THE FAN. There is plenty of air/wind in there.

Image


I don't understand how you are venting it between shots. How do you get fresh air in and the spent air out? Are you using the torch to bring in air with the propane? If so the mix may be slightly rich. Most torches depend on some secondary air besides the venturi injected air. Do you have a photo of the torch head install. Does it draw air from outside the chamber?

Never mind.. It looks like the torch vents are outside the chamber.
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Unread postAuthor: Ragnarok » Fri May 29, 2009 12:20 pm

chenslee wrote:STFU ABOUT THE FAN. There is plenty of air/wind in there.

And you're not reading what people have said. Fans are not just about fuel mixing.

If running, they cause chamber turbulence. This then increases the flame front propagation rate in the fuel, improves the pressure rise in the chamber, and with it, brings greater muzzle velocity and power.
At the same time they also improve shot to shot consistency.

You might not NEED a fan, and I'm not saying that you have to put one in there, but the fact that you're getting ignition every time does NOT mean that having a chamber fan can't still offer a large slew of benefits.

Anyway, very impressive video.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: chenslee » Fri May 29, 2009 4:11 pm

I agree. A fan probably would help, but this setup just doesn't lend itself to a fan.

First of all, I'm fueling when the bolt is back. Running the fan during this operation and swirling around the fuel and air is going to mix more outside air in, and eject even more fuel to atmosphere.

Second, I'm not going for power or distance. I'm going for reliable and easy to use. If I wanted to go for distance I have a chunk of 3" bore, 36" long aluminum body I could have adapted and made a single shot.

Third, the Bernzomatic stem I'm using has three sections. The first section is an orifice, the second is a venturi carburetor, and the third section (the tip) has mixing vanes in it. As far as I'm concerned, the fuel and air are mixed already.

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Forth, if I ran the fan after I shut the bolt, it adds a step to the firing process; something I don't want to do.

Update:

I ran about 100 balls through outside and the new setup yielded about 50% more range than the airpump/orifice system. The balls feed beautifully and will even feed upside down.

Update:

I have a water filled frozen tennis ball at home now. I'm going to test it tonight.

Also: http://bernzomaticinjuries.com/bernz_002.html


Update:

Undaunted by 3rd degree burns, I made some fireballs. They feel warm and wet and smell like burnt hair if you were wondering.

[youtube]http://www.youtube.com/watch?v=pVmhNG4JFDQ[/youtube]

And some more random shooting

[youtube]http://www.youtube.com/watch?v=WbkyNxrjLDY[/youtube]


6-24-09
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