The Alpha Unit

black tide · Thu Nov 18, 2004 1:08 pm

<div align="center">THE ALPHA UNIT

Here's my Alpha Unit. I'ts the first cannon I've made and incorporates my own super high flow valve. It shot a tennis ball with loose foam wadding about a quarter mile at 60 psi. The barrel is 3" with a 4" valve (yes it is indeed 4 full inches of flow!!!!) Two 2" ports dump into it as you can see from the dual fill chambers. The first test I made with it was at just under 30psi and the valve opened so fast it blew it right out the back of it. So that's why there are straps holding a modified plug on the end of it so it still works. Oh, and the duct tape is for looks

~Andy
</div>

spudshot · Sun Mar 27, 2005 10:42 pm

looks cool but the reason the plug blew is because its NSF DWV, or not made for pressure, so is that double Wye you have on there, and the elbows. you should really use NSF- PW fittings only, as they are much safer, i'd be intrested in knowing how the valve works exactly, maybe some paint drawings or auto cad renderings?

SpudStuff · Thu May 04, 2006 9:37 pm

I think it might be a barrel sealing valve like in a copper piston but just with two inlet instead.

boilingleadbath · Fri May 05, 2006 7:06 pm

Your quarter mile measurment wasn't done very well.

I opened up calculator, and calculated that in an ideal system - no flow losses, no pressure loss during firing cycle, no wadding mass... a simple 400 some pounds of force for the full 10' of the barrel... your velocity is about 335 m/s.

I then opened the GGDT and made a launcher (uses 195 psi hydrogen through a burst disk, if you are interested...) that gets the same velocity with a 53 gram projectile.

Using the GGDT's built in flight simulator, and a Cd of .3 - which is way too low - I got a range of ~1/6 mile. I have to use a Cd of .18 to get .25 mile, which is moving in on dart territory.

So, in conclusion, it is compleatly impossible for you to have shot 1/4 mile with a tennis ball, unless you weighted it or something. If you did, I'd be happy to recalculate...

Edit: Oops, I need to pay more attention to where these things are posted... the above was a grand waste of effort, as the poster isn't coming back.

)DEMON( · Sat May 06, 2006 9:18 am

good,because i think you would have made him feel realy bad when he read that,if somebody likes to live in their own world then let them

SpudStuff · Sat May 06, 2006 10:24 am

i dont think the ducttape he put on it made it look better

SpudMonster · Sat May 06, 2006 7:39 pm

Only PCGUY can start threads here.

SpudStuff · Sat May 06, 2006 8:16 pm

not how this wasn't posted by PC Guy and what were you trying to prove

Flinchy · Sat May 06, 2006 11:03 pm

looks like a first timer all right. be careful when you purchase your piping, always read down the pipe to make sure its pressure rated. its a pretty creative design, however i think it would be a little better if you didn't have the barrel on the bottom.

Flinchy · Sat May 06, 2006 11:10 pm

looks like a first timer all right. be careful when you purchase your piping, always read down the pipe to make sure its pressure rated. its a pretty creative design, however i think it would be a little better if you didn't have the barrel on the bottom.

kris · Fri Sep 22, 2006 10:39 pm

have you herd of pipe cement

PVC Arsenal 17 · Fri Sep 22, 2006 11:13 pm

have you heard of dead topic?

you actually think duct tape would really work? It's to cover up primer stains.

killagorrila99 · Sat Sep 23, 2006 1:13 am

HAHA MAN! I actually pressure tested duct tape! Ya no what it can hold? !100 psi! WOW!

PVC Arsenal 17 · Sat Sep 23, 2006 2:57 pm

yeah but i'm sure it leaks like mad