Combustion or Pneumatic Cannon?

A place for general potato gun questions and discussions.
D-Roc
Private 4
Private 4
Posts: 84
Joined: Wed Mar 22, 2006 7:31 pm

Wed Apr 26, 2006 8:14 pm

Should I build a simple combustion cannon or a simple ball valve
pneumatic cannon? Which has the most FPS and range?
User avatar
jrrdw
Moderator
Moderator
United States of America
Posts: 6569
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Has thanked: 39 times
Been thanked: 22 times
Contact:

Donating Members

Wed Apr 26, 2006 8:22 pm

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!
User avatar
Atlantis
Corporal 5
Corporal 5
Posts: 955
Joined: Sat Sep 03, 2005 10:26 pm
Location: Florida

Wed Apr 26, 2006 8:53 pm

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.
"There isn't a problem in the world that can't be solved by the proper application of explosives"
pipeguru777
Private 2
Private 2
Posts: 24
Joined: Wed Apr 19, 2006 9:23 pm

Wed Apr 26, 2006 9:29 pm

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.
User avatar
boilingleadbath
Staff Sergeant 2
Staff Sergeant 2
Posts: 1635
Joined: Sat Mar 12, 2005 10:35 pm
Location: Pennsylvania, USA

Wed Apr 26, 2006 10:01 pm

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.
D-Roc
Private 4
Private 4
Posts: 84
Joined: Wed Mar 22, 2006 7:31 pm

Wed Apr 26, 2006 10:12 pm

How do I spring a ball valve?
User avatar
Shrimphead
Corporal
Corporal
Posts: 509
Joined: Thu Nov 17, 2005 7:42 pm

Thu Apr 27, 2006 5:42 pm

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.
Controlled insanity = Genius
Life flies when you're being dumb.
User avatar
noname
First Sergeant 4
First Sergeant 4
Posts: 2698
Joined: Mon Apr 10, 2006 9:19 pm
Location: Bay Area, CA

Fri Apr 28, 2006 11:04 pm

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
User avatar
SpudStuff
Sergeant 5
Sergeant 5
Posts: 1410
Joined: Sat Dec 10, 2005 3:55 pm
Location: Cupertino, California
Contact:

Fri Apr 28, 2006 11:09 pm

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

Kids getting cancer = Bad ( not good)
User avatar
Shrimphead
Corporal
Corporal
Posts: 509
Joined: Thu Nov 17, 2005 7:42 pm

Fri Apr 28, 2006 11:22 pm

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! :twisted:

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!).
Last edited by Shrimphead on Fri Apr 28, 2006 11:26 pm, edited 1 time in total.
Controlled insanity = Genius
Life flies when you're being dumb.
User avatar
saladtossser
Sergeant 3
Sergeant 3
Posts: 1234
Joined: Sat Mar 26, 2005 10:40 am
Location: Toronto
Contact:

Fri Apr 28, 2006 11:25 pm

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
"whoa... I thought pimpmann was black..."-pyromanic13
User avatar
CS
Moderator
Moderator
Posts: 1837
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah

Donating Members

Fri Apr 28, 2006 11:47 pm

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...
Benny
Corporal 4
Corporal 4
Posts: 844
Joined: Wed Apr 19, 2006 8:21 pm
Location: Tasmania, Australia.

Sat Apr 29, 2006 12:02 am

back on topic, i would go with a barrel sealing piston valve, its much easier than you think. :)
User avatar
boilingleadbath
Staff Sergeant 2
Staff Sergeant 2
Posts: 1635
Joined: Sat Mar 12, 2005 10:35 pm
Location: Pennsylvania, USA

Sat Apr 29, 2006 1:02 pm

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.
User avatar
LucyInTheSky
Specialist 2
Specialist 2
Posts: 293
Joined: Fri Apr 21, 2006 11:46 am

Sun Apr 30, 2006 6:15 am

Go hybrid!!! :twisted:
Post Reply