Using metered propane (or MAPP, or butane, or....) will be more efficient then dropping some alcohol or gasoline in the chamber. There are several threads here, along with several calculators in the wiki that will assist with any questions you have on that subject.
Another thing you could do is use some math and figure out how many drops to put in chamber (although building a meter may be easier, as gasoline and such have impurities that will affect performance).
Loss of power
That reminds me of another problem I was having when I first built my launcher and it was "Spray & Pray"....After every shot I had to "hand" fan the chamber and barrel so fresh air would be there for combustion. If I didn't I wouldn't get good shots. The very reason I installed a combustion fan.
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Kaotik Kustoms
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Which way do i want to to vent my cannon? Should i have the fan vent towards the barrel or the back of the chamber?
vent to barrel,rear to front.
You will end up spraying the hair/deodorant stuff to the side of fan. Small fan will be fine.
The electrodes will have to be cleaned so keep that in mind when installing fan. The starch and goo from sprays will end up grounding electrodes.<a title="IMG_0095-1.jpg" href="http://s116.photobucket.com/albums/o12/ ... .jpg"><img src="http://i116.photobucket.com/albums/o12/ ... 0095-1.jpg" border="0"></a>
You will end up spraying the hair/deodorant stuff to the side of fan. Small fan will be fine.
The electrodes will have to be cleaned so keep that in mind when installing fan. The starch and goo from sprays will end up grounding electrodes.<a title="IMG_0095-1.jpg" href="http://s116.photobucket.com/albums/o12/ ... .jpg"><img src="http://i116.photobucket.com/albums/o12/ ... 0095-1.jpg" border="0"></a>
Propane is definitely THAT MUCH better and beyond... It can increase muzzle velocity over 200 miles per hour (about 300 fps) in some cases....
If your not ready for propane (you seen like your interested though), try adding a chamber fan first...
How are you spraying denatured alcohol and gasoline into the chamber? A regular spray bottle should atomize the liquids enough so that they blend decently with the air... Directly pouring them in definitely doesn't work (but you did mention spray).
After every shot try to thoroughly evacuate the exhaust fumes from the chamber so it is full of nice clean air... Blowing into the chamber with your mouth will most likely result in hot corrosive fumes blowing into your eyes and nose... Which for some reason doesn't bother me, but there's no way it's good for you
.... From one of the most safety conscious people here 
Normally smaller propane tanks are used, but it is possible for 20lb tanks to be used...
It matters on the size of your chamber really, but you do get quite a few (actually many) shots from even small camping size (1lb or 14.1 oz) propane cylinders.
edit: some people posted during my typing...
An added note on chamber fans... Covering the electrodes in hot glue\epoxy will help isolate them from corrosion and shorting, so take prevention measures before installing the fan, so you don't have to fiddle with it later.
If your not ready for propane (you seen like your interested though), try adding a chamber fan first...
How are you spraying denatured alcohol and gasoline into the chamber? A regular spray bottle should atomize the liquids enough so that they blend decently with the air... Directly pouring them in definitely doesn't work (but you did mention spray).
After every shot try to thoroughly evacuate the exhaust fumes from the chamber so it is full of nice clean air... Blowing into the chamber with your mouth will most likely result in hot corrosive fumes blowing into your eyes and nose... Which for some reason doesn't bother me, but there's no way it's good for you
.... From one of the most safety conscious people here Normally smaller propane tanks are used, but it is possible for 20lb tanks to be used...
It matters on the size of your chamber really, but you do get quite a few (actually many) shots from even small camping size (1lb or 14.1 oz) propane cylinders.
edit: some people posted during my typing...
An added note on chamber fans... Covering the electrodes in hot glue\epoxy will help isolate them from corrosion and shorting, so take prevention measures before installing the fan, so you don't have to fiddle with it later.
-FrOgY-
I wish people would stop needing a better signature!
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Kaotik Kustoms
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frogy wrote:Propane is definitely THAT MUCH better and beyond... It can increase muzzle velocity over 200 miles per hour (about 300 fps) in some cases....
If your not ready for propane (you seen like your interested though), try adding a chamber fan first...
How are you spraying denatured alcohol and gasoline into the chamber? A regular spray bottle should atomize the liquids enough so that they blend decently with the air... Directly pouring them in definitely doesn't work (but you did mention spray).
After every shot try to thoroughly evacuate the exhaust fumes from the chamber so it is full of nice clean air... Blowing into the chamber with your mouth will most likely result in hot corrosive fumes blowing into your eyes and nose... Which for some reason doesn't bother me, but there's no way it's good for you
Normally smaller propane tanks are used, but it is possible for 20lb tanks to be used...
It matters on the size of your chamber really, but you do get quite a few (actually many) shots from even small camping size (1lb or 14.1 oz) propane cylinders.
I was using a $1 store spray bottle but i would still have left over liquid that wouldnt burn.
I have no problem running propane if it is that much better. I just watched a vid on how to make a meter for propane.
How do i figure out how much propane i need to send to the chamber?
That is why there are tools like Prometer. At the top right of this page under "Archive" is "Other". Click on that then Computer Applications. You must first determine the volume of your chamber only. You can calculate this or fill it up with water then empty it into a measuring cup. Figure about 4.3 percent propane. I tried more but I always use that. It will ask you to enter a desired pressure as well; I use 55psi but I also use 90psi. Ask around to see what others use. Enter the info in the spreadsheet, chose the diameter of the meter pipe you want and voila...you have the length. You then need some hardware and tools. It takes a while but you'll love the results. I'm now propane and I'll never go back
I believe this video tutorial at BCVids is pretty good, but you will have to make an account there to watch it...
http://www.bcvids.com/dload.php?action=file&file_id=24
Normally a propane meter is pretty cheap to make... All it requires is a few pipe nipples, a 90 elbow, a tee, a pressure gauge, and 2 ball valves to make the meter assembly... Plus a few more dollars to adapt it to connect to a propane tank.
http://www.bcvids.com/dload.php?action=file&file_id=24
Normally a propane meter is pretty cheap to make... All it requires is a few pipe nipples, a 90 elbow, a tee, a pressure gauge, and 2 ball valves to make the meter assembly... Plus a few more dollars to adapt it to connect to a propane tank.
-FrOgY-
I wish people would stop needing a better signature!
I wish people would stop needing a better signature!
Whoa, should I be worried? I'm a first-timer who just slapped together an extremely simple combustion cannon using some generic 5 euro PVC pipe pieces and a PC fan, and so far I've only shot some potato pieces and such using deodorant.frogy wrote:Propane is definitely THAT MUCH better and beyond... It can increase muzzle velocity over 200 miles per hour (about 300 fps) in some cases....
If your not ready for propane (you seen like your interested though), try adding a chamber fan first...
Is it risky or something to start using propane?
NSF-PW SCH 40 PVC and solid wall SCH 40 DWV ABS are both fine for metered propane combustions. SCH 40 DWV PVC is kind of iffy, and cellular core plastic pipe of any kind is a bad idea.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
I have no idea what kind of PVC mine is...
Already with deodorant the spud gun is much more powerful than I expected - the spud is so fast that I can't see it in flight, and when shooting solid objects the potato only leaves a wet splat. I just hope the chamber doesn't blow up when I move on to a 50/50 butane and propane mix.
I have heard that PVC explodes into shards when it fails. Is it an "ouch" thing, or is it particularily dangerous? Will I be OK with just eye protection?
Already with deodorant the spud gun is much more powerful than I expected - the spud is so fast that I can't see it in flight, and when shooting solid objects the potato only leaves a wet splat. I just hope the chamber doesn't blow up when I move on to a 50/50 butane and propane mix.
I have heard that PVC explodes into shards when it fails. Is it an "ouch" thing, or is it particularily dangerous? Will I be OK with just eye protection?
I have 1 piece of cellcore in my launcher. I used it, unknowingly, to hold the two pvc fittings that make up my combustion chamber. It's only as long as the shoulders of the two fittings but it's cellcore all the same. I think the only thing in my favor is that I don't go crazy with the propane. When I start buying for my next launcher I'll be more careful. Remember, just because Lowes carries pressure rated pvc in 1/2, 3/4 and 1 1/2 inch doesn't mean the 3 inch is pressure rated as well. My lesson learned was to read all the damn labels.
As far as eye protection, that's up to you. Don't hold the thing on your shoulder like a bazooka.
As far as eye protection, that's up to you. Don't hold the thing on your shoulder like a bazooka.
I'm not sure how Europeans rate their PVC...
Deterrent can you please take a picture of the pipe your chamber is make out of? The writing on the pipe would help us greatly to determine if it is safe or not...
Deterrent can you please take a picture of the pipe your chamber is make out of? The writing on the pipe would help us greatly to determine if it is safe or not...
-FrOgY-
I wish people would stop needing a better signature!
I wish people would stop needing a better signature!
