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Going all out...but im stuck.
Posted: Tue Nov 15, 2011 11:40 pm
by xKantor101
I am finally deciding to build my biggest and baddest cannon yet, which may not be so big and bad to you guys.
I want to use a fan/electric ignition/propane meter in this cannon. its a big step up from the spray and pray cannon which ive built many times before. i understand how to build most of this project, but i dont know what to do about air mixture. if i use a propane meter, how can i get air into the chamber? ill sketch up some plans tomorrow during school and post them up here so u guys can see where im stuck.
Posted: Wed Nov 16, 2011 12:31 am
by jackssmirkingrevenge
If you have a fan, it will blow air down the barrel after each shot, giving you all the fresh air you need.
Posted: Wed Nov 16, 2011 7:41 pm
by motorfixer1
Instead of a screw on plug you will have some sort of valve between your chamber and the atmosphere to allow the entry of fresh air between shots. Thats as far as I can spoon feed.
Posted: Wed Nov 16, 2011 10:46 pm
by chronicod4
just went through that phase from spray and pray to propane metered injection , inside fan , dual sparks and a rifled barrel but it is not totally done just needs to work out all the bugs. But you will need a fan to mix the propane and air and to vent the cannon if you don't your cannon will be unreliable and you wont get all that much more power out of it.
Posted: Thu Nov 17, 2011 8:42 pm
by xKantor101
just added the pictures in hope that they can get what im trying to say across.
Posted: Thu Nov 17, 2011 9:04 pm
by Gun Freak
Plan B will be much quicker, I would think.
Posted: Thu Nov 17, 2011 9:19 pm
by xKantor101
well i think ill choose B but i just dont want to have to have it be open while i fuel the chamber. it brings back terrible memories of rushing the shot due to escaping gas while screwing it back on. maybe have it open while venting and loading, then when i fuel have it closed.
Posted: Thu Nov 17, 2011 9:32 pm
by MrCrowley
Yeah, you have the cap closed when fueling. After the shot, you open the cap to vent the chamber and then screw it back on before fueling.
Posted: Fri Nov 18, 2011 1:04 am
by jackssmirkingrevenge
MrCrowley wrote:After the shot, you open the cap to vent the chamber and then screw it back on before fueling.
If the fan is blowing the gas out of the barrel I don't see the need to open the cap...
Posted: Fri Nov 18, 2011 1:10 am
by MrCrowley
Just repeating what most others do on their builds, I've never built a combustion with a fan personally
Wasn't sure how great the flow would be since you essentially have one opening for both gas outlet and gas inlet (the barrel) especially if the fan is near the back of the chamber.
Posted: Fri Nov 18, 2011 7:46 pm
by motorfixer1
You should trash that DWV cap and go for a pop valve or a ball valve instead. Those things are molded from thin PVC and the increased energy of a metered propane setup could prove to be devastating to the cap and those around it when it eventually fails. Furthermore all of the parts you use should bear the NSF-Pw badge meaning they are for use with pressurized water. If not you are flirting with disaster. Just my $0.02