ok well i tried to mod the valve, i got it done with 1/4 npt but it was threaded into about 3/32 thick plastic so i decided for a bigger diameter (3/8 npt) but i couldn't find a tap to tap the hole so i put the flow control back in and tried it with the solenoid.

MERGED:

http://i182.photobucket ...

ok so i build my cannon and put the valve in with the arrows pointing in the direction of the flow, the only problem is when i pressurize it it leaks down the tube. i checked everything there's no debris on the diaphragm or the seal. but i noticed the pressure balance hole goes from the output part ...

well the loop i was thinking of was you need the reynolds number to calculate the Cd of the object, and you need velocity for the reynolds number and then each shape has a graph that has no equation (it's based solely on experimental data) that needs to be examined by hand each time, for every ...

To actually find the velocity using drag you need math physics and science that is way above high school level, and you would need matlab and know how to program in it. To do drag correctly it is very complicated and technically impossible to solve because to find the drag you need the velocity, but ...

i was going for more of

i'm not an idiot know how these systems work but you guys have more practical experience.

i knew the mythbusters used one but if any one here has maybe they could compare how it flows compared to a sprinkler valve even though the butterfly would be manually opened

Has any one tried using a butterfly valve?

Here is where you would find expensive valves, they are industrial valves not sprinkler and say they are good to 150 psi, but could probably take many of thousands of psi before it would yield.

And well this is my first pneumatic gun, i have a combustion one that'll put a golf ball out to about ...

Ok to start out i am not an idiot i am a mechanical engineer and know more about some of these things than you guys do i just choose not to put the hours into trying to solve a problem when i could ask for help of someone who has more practical experience. I am constructing a golf ball cannon i know ...