I need combustion chamber math help for 3 or 4" barrel.

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
Essohbe
Private 2
Private 2
Posts: 26
Joined: Wed Feb 22, 2012 4:30 pm
Location: McMurdo, Antarctica

Sun Dec 16, 2012 4:22 pm

Alright, I am TERRIBLE with math and I need help figuring out how big a combustion chamber I'd need for a 6" PVC chamber with a 4" PVC barrel (or 3").

Will be metered propane most likely. I know there's formulas but I don't know how to add in all my variables.

Thanks anyone for any direction you can give me.
User avatar
mobile chernobyl
Corporal 3
Corporal 3
United States of America
Posts: 756
Joined: Sun Dec 03, 2006 11:53 am
Been thanked: 7 times

Sun Dec 16, 2012 5:07 pm

If you haven't already - read this:
http://www.spudfiles.com/spud_wiki/inde ... rrel_ratio

And all you need to know is there.

You really should be able to do this little bit of math!
User avatar
CS
Moderator
Moderator
Posts: 1837
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah

Donating Members

Sun Dec 16, 2012 6:34 pm

jsefcik
Sergeant 2
Sergeant 2
Posts: 1138
Joined: Tue Jun 07, 2011 10:11 am

Sun Dec 16, 2012 9:59 pm

what ever your chamber is double that with your barrel,

if your chamber is 1.5 feet make your barrel 3 feet and so on
User avatar
mobile chernobyl
Corporal 3
Corporal 3
United States of America
Posts: 756
Joined: Sun Dec 03, 2006 11:53 am
Been thanked: 7 times

Sun Dec 16, 2012 10:22 pm

Sorry Jsefcik - that does not work in all cases. In fact, that will rarely work. Sure it will produce a spud gun - but not an optimized one.
User avatar
pneumaticcannons
Specialist 3
Specialist 3
Posts: 392
Joined: Sat Oct 30, 2010 9:45 am
Location: shite country in asia
Contact:

Mon Dec 17, 2012 12:25 am

I am TERRIBLE with math
Not exactly the best hobby to be terrible at math in.
Don't take that the wrong way, i'm not telling you to quit, just ask your math teacher for help or something... lol
How old are you?
ramicaza <- My Youtube Channel
Essohbe
Private 2
Private 2
Posts: 26
Joined: Wed Feb 22, 2012 4:30 pm
Location: McMurdo, Antarctica

Mon Dec 17, 2012 12:29 am

Very cool, thanks guys. I think I got it. That calculator link is AWESOME btw...

LOL, yeah I'm 32 BTW... I failed every math class in high schooll then flunked 6 of them in college until they let me take geometry instead which I tested out of. Go figure.
jsefcik
Sergeant 2
Sergeant 2
Posts: 1138
Joined: Tue Jun 07, 2011 10:11 am

Mon Dec 17, 2012 1:51 pm

mobile chernobyl wrote:Sorry Jsefcik - that does not work in all cases. In fact, that will rarely work. Sure it will produce a spud gun - but not an optimized one.

thats what i always went by, sorry about that
Essohbe
Private 2
Private 2
Posts: 26
Joined: Wed Feb 22, 2012 4:30 pm
Location: McMurdo, Antarctica

Sat Dec 29, 2012 10:22 am

Does putting a bend in the barrel coming out of the chamber impede the combustion at all or affect the ratio? I've seen both types of straight and bent chamber-to-barrel designs and it doesn't seem to matter.

Any comments?
User avatar
PaperNinja
Specialist
Specialist
Posts: 190
Joined: Sun Jun 17, 2012 7:51 pm
Location: Droneland

Sat Dec 29, 2012 10:42 am

It slightly reduces flow, but I don't think the effect is very significant.
Essohbe
Private 2
Private 2
Posts: 26
Joined: Wed Feb 22, 2012 4:30 pm
Location: McMurdo, Antarctica

Sun Dec 30, 2012 12:09 pm

Good to hear.

QWERTYUIOP{ASDFGHJKL
Post Reply