SpudFiles

Just finished my tennis ball cannon, and realized that my C:B ratio was probably way out of whack. ATM: MY 4'by 2.5" barrel has a volume of 235 CI, my 3' by 3'' chamber measures in at 254. For a combustion the best ratio is between .6 and .8, What would it be for a pneumatic? about the same?

It is fine.....

Gun Freak wrote:It is fine.....

Thanks.

You can simulate any cannon design you want and receive estimated performance for such design using a program called GGDT. Any information you require about using the program can be found on the site so be sure to read it over before asking for help with it.

Last stupid question, what would you select for valve type if using a modded sprinkler valve?

Search the GGDT site. Depending on what model and size you have, there should be an accurate representation for the valve. I think it's under the "Archives" section.

Mr.Tallahassee wrote:Search the GGDT site. Depending on what model and size you have, there should be an accurate representation for the valve. I think it's under the "Archives" section.

Found it. Thanks.

Gidney14 wrote: For a combustion the best ratio is between .6 and .8, What would it be for a pneumatic? about the same?

For high pressure, I prefer a CB of 1:1

For low pressure, you want larger chambers. For high pressure, if the compressor supply is not an issue, large is good, but has diminishing returns. For hand pumping, a smaller chamber can reduce performance a little while cutting the workout on the hand pump to a managable workout.