SpudFiles

Should I build a simple combustion cannon or a simple ball valve
pneumatic cannon? Which has the most FPS and range?

The pneumatic cannon is faster and shoots farther. I'm collecting parts to build one myself, my chambers are a old Emglo gas engine powered air compressor tanks(steel), my barrel is gonna be 3" diameter Sch 40 (6 foot long), and i'm going to build a 2" piston valve, it should turn out sweet!

I think he's asking, between a combustion and apneumatic with a BALL VALVE, which has more power? Good question, ball valves aren't very good. Add a spring to it to open faster and a pneumatic will own a combustion.

how are you planing to build that valve jrrdw. i'm hopeing to make 2 2'' piston valves for a big canon i what to build, much thanks for any help.

Although the only combustion gun simulator we have is based on metered-propane and chamber fan data, here goes nothing...

Assuming you are using a 2" barrel, and can open a 2" ball valve in 1/10th of a second. (calculations preformed using the GGDT for pneumatics and EVBEC for combustions)

The pneumatic with a 12"x4" chamber and 50" barrel at 120 psi will beat a combustion with the same barrel and chamber for any projectile 200 grams or heavier.
With a longer barrel the preumatic will beat the combustion with lower projectile masses.

So basicaly, unless you use a spring to actuate your ball valve or something to that extent, the 'advanced' combustion will be more powerfull with most projectiles. (as well as being more portable)
Without the chamber fan and using an aerosol, the pneumatic will probably win for most projectile masses - chamber fans add a LOT of power, on the order of 60% more.

How do I spring a ball valve?

You could just use a sprinkler valve. They only cost about 15$ US. But you would probably want to mod it (look it up in the how to's) which would cost about 5-10$ more.

Go with pneumatic. They are more complicated than combustions ( if you could say its complicated i would smack you even if i had to stretch my hand all the way from CA) but more powerful. Combustions also use aerosol, which is REALLY REALLY bad for the ozone layer. So use combustions and all of our kids get cancer. sounds fun

Ozone has nothing to do with Cancer. the only thing is UV and skin cancer.

Kids getting cancer = Bad ( not good)

Scientists during the late 80s and early 90s (I think that's the right time period) thought that the common use of aerosol products were increasing the size of the hole in the ozone layer. Since then, it has been noted that the hole fluctuates in size naturally and that the use of aerosol has little to nothing to do with it size. That's why the craze for non-aerosol products has dropped since then. So really, the use of aerosols is safe and fun!

Edit: The most reliable and powerful fuel commonly used in combustions is propane. Propane is non-aerosol I believe, so even IF I am wrong about the aerosol thing, as long as you use propane you're safe (not to mention you have a better gun!).

noname wrote:Combustions also use aerosol, which is REALLY REALLY bad for the ozone layer.

aerosols do not contain cfcs anymore, no damage to the ozone layer

Im pretty sure one moderate volcanic eruption spews just as many atompshere/ ozone depleting agents as all the aersols being sprayed in the whole world. If your some wackjob enviromentalist why are you shooting spudguns??? Remeber guns kill people, people dont kill people. Remeber, weeding is plant racism...

back on topic, i would go with a barrel sealing piston valve, its much easier than you think.

Pimpmann, watch your stereotyping...

Anyway, to adress the concerns of ozone damage from your fule - if your aerosol contained CFCs, which arn't flamable - it wouldn't be of any use to us. Nowadays, as saladtosser said, CFCs have been fazed out and replaced with the fun stuff: alkanes.

Go hybrid!!!