SpudFiles

Hmmm.... Where to start...

Well I have decided to go big...giant.... OK Gigantic!

I'm going to launch pumpkins! Thats right 8-10LB PUMPKINS!

I found out that there are a few local meet here in Washinton. A friend of mine is on a team with a trebuchet. They are cool but not my style.

I have a few ideas...but am looking for all the input I can get!

I'm thinking of a Low Pressure, High Volume design but that is just a thought. The basic design will be a 200+ gallon propane tank (chamber) valve assembly and a 10 inch barrel (thinking about 20 feet long). And it will be mounted to a trailer.

I want to start with the valve body. I could use a 10-12 sprinklers
But I was first thinking Piston! Any one seen a 6 inch piston!! Or would a BDisc be better?

Any thoughts are greatly appreciated!

burst disk is supreme, as long as it doesn't exit the barrel(against the rules) or break the pumpkin with the shock.

Butterfly valves are commonly used becasue of their slowness; this protects the pumpkin. There was some talk of a captive sabot that would protect the pumpkin recently.

JSR proposed design to protect the pumpkin from the BD with a captive bolt, I'd go for that if I were you

The designs proposed here are pretty well the best you'll find. Using the proposed system, a fast valve is suggested, since the spring will decrease the initial acceleration of the pumpkin on the captive sabot.

@ramses:

The burst disk D-Hall used on Vera doesn't release any shrapnel. maybe you should take a look at it.

Also, wouldn't it be great to organise a punkin-chunkin event with "unlimited class"?

You could build a massive hybrid then

That burst disc design is a serious valve possibility if using the captive sabot, but it would probably require a lot of experimentation to get it to burst just right.

A massive hybrid would probably make pumpkin mist... There's sadly not much place for hybrids in throwing vegetables since they don't survive the massive accelerations.

I like the B-D for the simplicity of its design, but I fear it will damage the shell of the pumkin.

I read a thread on a double B-D design... one in front of the other to allow more psi in the chamber. So that got me to thinking.. if I used a ball valve in-line with a B-D. Then the pumkin would start to move with the opening of the B-V and when the psi dropped on the barrel side of the B-D then it would release the rest of the pressure, thus accelerating the pumkin.

I will be building a "mini" and I think bell peppers will make a similar projectile.