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Propane help.

Posted: Sun Aug 27, 2006 5:33 am
by Travisimoo
Hello spudfiles :o
So, my kid brother found a pvc pipe in the dumpster..and brought it home. I've seen spudcannons on youtube several times and after seeing the bbq igniter, I realized.. "holy crap this is a potato cannon O_O"

So, yeah...

thats how I got into spudgunning.

Now I've got a question regarding propane uzage...
I did use the search button, came to no avail...

So on to the question at hand.
I remember reading on a site [Either here or SpudTech.com] that if I used a blowtorch head on my propane tank, I wouldn't have to worry about the proper oxygen to fuel ratio too much, because the blowtorch head takes care of that...

So, after using a 1 second shot of propane into the combustion chamber, and igniting..nothing?

So I tried 2 seconds, and three..and even four, giving ample time [around 5 minutes] to vent the chamber...all to no avail.

1.5" 5 ft barrel...
3" 2 ft combustion chamber...

Thanks for reading, and any help will be apprediated...


-Travis.

Posted: Sun Aug 27, 2006 6:06 am
by rna_duelers
www.burntlatke.com has everything and a tool that u just type in the volume of your cannon and it tells you how big a pipe u need,its the best combustion site i no of.

Posted: Sun Aug 27, 2006 6:19 am
by Travisimoo
Sweet, thank you..
How do I found the volume of my cannon / combustion chamber?

Posted: Sun Aug 27, 2006 8:13 am
by LucyInTheSky
pi*radius of pipe^2*length of pipe

pi = 3.14159

Posted: Sun Aug 27, 2006 11:27 am
by Mihlrad
opening the valve on the torch head, does not give you any ratio at all. It actually gives you worse accuracy in your fueling. The amount of propane you put it in varies every time because of the speed you are opening or closing the valve. The only way to not have to worry about your fuel amount, is by using a meter. Its all on burntlatke.com.

By the way, this is the pneumatic section.

Posted: Sun Aug 27, 2006 11:48 am
by dongfang
I used to have a gun larger than that, but I used a lot less fuel.

Try, instead of 1, 2 or 3 seconds, 1, 2 or 3 pretty light taps on the propane can (do you inject into a small hole you have drilled? If not, you might want to drill one. 1.5 millimeters or around there.)

If it ignites but performs lousily, it's most likely overfueled. If it makes hell of a bang, it's either slightly underfueled, or correctly fueled. If it doesn't ignite at all, it could be either. But 1 second sounds waaaaaaaaay to much in my experience. That's what my 9 litre chamber gun needed :wink:

Posted: Mon Aug 28, 2006 12:07 pm
by Travisimoo
dongfang wrote:I used to have a gun larger than that, but I used a lot less fuel.

Try, instead of 1, 2 or 3 seconds, 1, 2 or 3 pretty light taps on the propane can (do you inject into a small hole you have drilled? If not, you might want to drill one. 1.5 millimeters or around there.)

If it ignites but performs lousily, it's most likely overfueled. If it makes hell of a bang, it's either slightly underfueled, or correctly fueled. If it doesn't ignite at all, it could be either. But 1 second sounds waaaaaaaaay to much in my experience. That's what my 9 litre chamber gun needed :wink:
I don't think a 1 second shot out of MYYY torch head will do much at all.
Its only a 1/4inch pencil-point flame torchh...

By the way, I'm just putting the propane into the breech...I don't have any holes drilled or anything..except for the igniter.

Sorry that its in the Pneumatic section, I could have swore I put it in the combustion... :roll:

Anyone care to move? :arrow:

Posted: Mon Aug 28, 2006 4:19 pm
by Mihlrad
There is part of your problem right there. Just spraying the propane into the breech your losing a huge amount of what gets sprayed in. Its a gas, its not like it just stays in the breech, gas fills the area available to it. Close off the breech, drill a hole and thread the torch head.

Again, its all at burntlatke.com if you want us to help you, do the things suggested.

Posted: Mon Aug 28, 2006 5:12 pm
by Travisimoo
Alright, thank you so much guys :]

Posted: Mon Aug 28, 2006 6:45 pm
by schmanman
better yet, put a hose over the tip of the torch, then thread a hose barb into the PVC, and put a hose between them, connecting the two with the hose. that way, you can hose clamp the torch to the side of the cannon, and it wont be hanging off by the torch head at a weird and awkward angle (dont forget to hose clamp the two ends of the hose)

Posted: Mon Aug 28, 2006 7:42 pm
by Travisimoo
Hehe, I'm going to build an injection system with my sister :]

http://www.burntlatke.com/lp.html