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Softball + Propane = AWESOME!

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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Softball + Propane = AWESOME!

Unread postAuthor: xpitxbullx » Wed Jun 04, 2008 1:32 pm

My multi-barreled gun has a propane setup now. I can tell the difference between using Gumout Carb Cleaner and using the propane. Very consistent and about 20% more powerful. Hey, I still have to give Gumout it's props...it's still pretty good.

I wrenched off a propane torch top and used hose from a broken bicycle pump. The hose after the blowgun screws into a tire valve.

Softball w/Gumout distance (measured with a GPS) = 686 ft
Softball w/propane distance (measured with a GPS) = 885 ft!!!

Dialing it in today for a couple of hours was FUN! The softball attachment requires a little more propane than the other barrels. The rigging is zip ties for now until I build a nicer housing for it later.

Propane has made me a believer. Does it matter if the tank is right-side up or upside down when pressurizing?

Is MAPP gas any good for this setup?

Jeff
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propane setup.jpg
temporarily using zip ties
softball_cannon.jpg
all the barrels
softball_cannon.jpg (31.42 KiB) Viewed 748 times
Last edited by xpitxbullx on Thu Jun 05, 2008 2:59 pm, edited 2 times in total.
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Unread postAuthor: harmon12407 » Wed Jun 04, 2008 7:23 pm

Yep, MAPP is good for this setup.

According to the Latke Tests, MAPP yields slightly greater muzzle velocities than propane does, but it equates to about an 11% velocity increase for a 300% price increase.

http://www.burntlatke.com/lpmapprussets.html
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Unread postAuthor: Spuddin » Wed Jun 04, 2008 7:35 pm

850 feet is some wicked distance with a softball, thats a 4 inch chamber right? and about what psi do u use. great job!
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Unread postAuthor: xpitxbullx » Wed Jun 04, 2008 11:59 pm

harmon12407 wrote:According to the Latke Tests, MAPP yields slightly greater muzzle velocities than propane does, but it equates to about an 11% velocity increase for a 300% price increase.


Propane setup was about $60 for 20% increase. another $6 for 11% sounds like a bargain. :D

Spuddin wrote:850 feet is some wicked distance with a softball, thats a 4 inch chamber right? and about what psi do u use. great job!


4" chamber, 4" softball barrel (seated 4" above the breech to create a larger combustion chamber.

With the propane setup I have, I pressurize to 30 psi and when using the softball barrel I use 36 psi.

Thanks,
Jeff
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Unread postAuthor: drex » Thu Jun 05, 2008 12:08 am

map the bottle itself cost a hell of a lot more than a bottle of propane
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Unread postAuthor: starman » Thu Jun 05, 2008 12:37 am

Very nice! You've been making a lot of headway the last few days. Once you go to propane you wont want to do anything else. Looks like you've the fuel/air mix right too. MAPP offers a little more energy, however, without a burst disk setup, it's unlikely you'll see a significant performance difference from propane.

On your meter, you decided not to use a valve to close off the propane tank from the meter...?? How are you injecting the right amount? Resticter and quick shot method?

Keep the propane bottle upright...tends to leak liquid propane if upside down.
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Unread postAuthor: xpitxbullx » Thu Jun 05, 2008 4:05 am

There are 2 valves. There is a valve on the propane can adapter (hidden from view in my pic) and the blowgun is my other valve. I could have used a ball valve in place of the blowgun but I think this way looks better.

Since the barrels are detachable, I can make a burst disk segment right there. What kind of performance increase do you think a burst disk union can give me? Seems like a lot of work in between shots if I go that route.

I would do it if I could get another 300 feet out of it. The softball and rag wedges in there pretty tight as it is.

Jeff

EDIT: I took it out today and remembered to bring my GPS...
885 FEET!!!

Launched at about a 40 degree angle with the first bounce at 780 feet. I wonder what the initial speed is out of the barrel. Probably a couple hundred miles an hour. You can leave it to your imagination on what kind of damage that can do (if you're into damage possibilities) >:)
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Unread postAuthor: jimmy101 » Thu Jun 05, 2008 1:52 pm

xpitxbullx wrote:Since the barrels are detachable, I can make a burst disk segment right there. What kind of performance increase do you think a burst disk union can give me? Seems like a lot of work in between shots if I go that route.

But with the burst disk adaptor you can still fire the gun in the non-burst disk mode. Great for getting that kick-ass maximum range for bragging rights while still being able to reload quickly for days when you just just want to launch stuff a long way.

HGDT will help you estimate the increase in muzzle velocity obtainable with a burst disk.

I wonder what the maximum practical range is for a softball? Tennis balls (low mass, low sectional density) hvae pretty short max ranges.

What kind of softball are you using? IIRC, they come in a couple different masses and hardnesses. Perhaps switch to a heavier softball to increase the range? (Higher sectional density and greater mass will drop the muzzle velocity but increase the range.)
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Unread postAuthor: xpitxbullx » Thu Jun 05, 2008 2:09 pm

jimmy101 wrote:What kind of softball are you using? IIRC, they come in a couple different masses and hardnesses. Perhaps switch to a heavier softball to increase the range? (Higher sectional density and greater mass will drop the muzzle velocity but increase the range.)


I'm using a league regulation 12" softball. It feels as hard as a baseball. I don't think it comes in a heavier size. It's between 177-198 grams.

Jeff

EDIT: Ohhh, I just found a lacrosse ball at the park that fits PERFECTLY into my tennis ball barrel. It fits so good I don't think a tissue wad rapped around it will fit down the barrel. Its solid and heavy. :twisted:
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