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Need Help GGDT'ing my gun.... Please help...

Unread postPosted: Thu Aug 10, 2006 7:39 pm
Author: spudkpi
I have just made a coaxial piston cannon and i would liek to GGDT it but i dont know the exact inner and outer dia. of the chamber or the flow coef. or the friction of the projectile or any of it... if someone could give me a link to a walkthrough or just help me out I would greatly appreciate it... thanks.


Here's my gun: http://www.spudfiles.com/forums/viewtopic.php?t=3079&

Unread postPosted: Thu Aug 10, 2006 8:25 pm
Author: Steve-
i need help too, i can't figure out why the outer diameter would change anything because isn't that only the pipe wall width which only changes the strength of the pipe???

edit: i think i got it, the outer diameter is the inner diameter of your chamber and the inner diameter is the width of your valve input

new edit: i looked on the website and acctually the inner diameter is only for coaxial meanin the outer width of the tube inside the chamber.

newer edit: benstern beat me too the punch

Unread postPosted: Thu Aug 10, 2006 8:55 pm
Author: spudkpi
is it really? thanks man ill try it

Unread postPosted: Thu Aug 10, 2006 9:15 pm
Author: benstern
Inter diameter is only used if you have a coaxel cannon. Just put the inter diameter (exact not nominal size) of you chamber in the Outer Diam box.

Unread postPosted: Thu Aug 10, 2006 9:32 pm
Author: spudkpi
Thanks benstern.

Unread postPosted: Fri Aug 11, 2006 12:01 am
Author: Shrimphead
If you were to go to the "other" section of this site, then to "pipe info", you could find out the pipe dimensions.

Unread postPosted: Fri Aug 11, 2006 2:24 pm
Author: spudkpi
Yep there it is.... with a paintball it shows 635 ft/s at 80 psi.... thanks guys