tennis ball launcher chamber size??

[ovie707]

im going to make a tennis ball cannon so i made the barrel 2.5inches

what size should i make the barrel for optimal performance

[rednecktatertosser]

Firstly is it going to be pneumatic or combustion?

If pneumatic then what kind of valve will you be using?

Details my friend... Details. Use the search function, and do some research before you ask question like this, some of the people here dont take kindly to this kind of post....

EDIT: sorry for that slip up, I defiately missed the combustion section tag up top, just come here from recent topics! sorry guys.

[SpudFarm]

DETAILS!!

[ovie707]

Firstly is it going to be pneumatic or combustion?

If pneumatic then what kind of valve will you be using?

Details my friend... Details. Use the search function, and do some research before you ask question like this, some of the people here dont take kindly to this kind of post....

its in the combustion section isn't it?? and i did search it didn't come up with anything useful

its a combustion cannon that uses pvc pipe

[Hubb]

Obviously, you didn't search too much. I'm in a good mood so I'll point you in the right direction. Search for chamber to barrel ratio.

Besides, where are the details that were asked for?

[ovie707]

sorry im a noob at this and need some time to get used to it

[SpudFarm]

you need to write your post like this:
"hey guys, i am new to this hobby and i have a simple question. i wonder how big i should make my combustion chamber for a xx" long 2.5" sch40 barrel"

[Hubb]

Good.

Burnt Latke has plenty of information that may help you. Check out his data tests for ratio findings.

[ralphd]

Well, let me just say that launching tennis balls is a lot cleaner than spuds. Burnt Latke is a good place for info but I like to hear "real life" stories.

My launcher was first designed to have a .8 to 1 barrel and it was very loud which means energy is being wasted up the barrel. I then found through Burnt Latke's research that .7 to 1 was optimal so I bought a connector and lengthened my barrel by 8 inches.

Theoretically my muzzle velocity increased but now I have a heavier launcher and my noise problem is still there.

Don't get me wrong I like the posted research to focus my design but I still like to ask questions to get "real people" response despite the asses cutting me down.

[Hubb]

Burnt Latke conducted his experiments using potatoes as ammo. Potatoes are heavier than tennis balls, which means the C:B for spuds is going to be different than for tennis balls. Tennis balls are going to accelerate faster.

I would start with a larger C:B (maybe around 1:1) then work from there.