SpudFiles

schmanman: I actually have a question about your piston valve: Why did you make the back of it so long? My <a href="http://www.spudfiles.com/forums/viewtop ... 1&">piston valved cannon</a> is very similar to yours (The only significant differences are that your cannon has chambers 2X as large as mine, in addition to much larger barrels, and my valve has about 2.25X the flow of you valve). I'm not ragging on your cannon (its a beast), but I was just wondering (anyways, I doubt that the longer piston body negatively affects the performance).

A <a href="http://www.spudfiles.com/uploader/uploa ... PG">pic</a> of my valve

Since our cannon hasn't been posted yet i won't argue the point any more, but our cannon is bigger than both of Joel's mega launchers. I won't say anymore about it until the cannon is entered in the constest and you can all see what we're talking about. Until then - i pity the doubters

Just post it already so we can critizie you even more

How do you know It has 2.25 times the flow of my valve? and also, I recently rebuilt the valve and shortened it up. believe it or not, I can now swap between 4 inch to three inch (three inch is the barrel side) and 4 inch to two inch porting. so I am not sure that you have 2.25 times the flow if they both have four inch to three inch porting.

It works like this

you put the bushing from 4 inch to 2 inch with the lip ground out in a 4 inch male threaded adaptor that screws into the front of the tee. like this.and viola, interchangeable porting
______
(_____)}} ----{{{--
-- [__]

TEE }}= female threaded adaptor

{{{= male threaded adaptor

-------- =pipe going through adaptor (barrel screws on to here)

but our cannon is bigger than both of Joel's mega launchers.

mine Is too. 18 foot barrels, and 10 feet of 6 inch diameter chamber. how big is it?

Well this was before I heard about your valve-swapping thingy; heres how I figured it out:

My valve (3" porting): ((3/2)^2)pi; =2.25 pi
Your valve (2" porting): ((2/2)^2)pi; = 1 pi

I'd like to see this updated valve; I think I understand how it works

My question is, why not just stick to 3" porting for the whole time?

My valve is 4" and 4" out but I havent made it yet out of sch40 so I cant say to much about it untill I get some pics of it.

wtf is your problem? He was only saying yours is a huge cannon.

And that 4" valve will be more powerful than yours as it has 3" outlets.

OOOOPS never saw there was a 3rd page! :EDIT

what have you made it out of then? Post pictures of that, even if it isn't pressure rated

schmanman why did you make a co-axal valve? you should have put the sealing area further forward so it was over the middle bit on the T. It would increase flow alot as you havent only go the area between the 2" and 4" pipe for the air to flow. Co-axals are alot eaisier to make I think.

Rmich732 thats a really clean looking valve, no primer stains. I think it looks as good as joels supah.

Bluetooth: thanks! I am really happy about how it turned up, but it is not nearly as compact as Joel's megah/supah valve). If I had a lathe and 4.5" Type II PVC rod, things might be a little different though

I have a bunch of videos (none are really great, I used super-low pressures [under 30 PSI on all of them] just to show how the cannon works; I'll post them in the section with the cannon in it

schmanman: dual 6" by 48" chambers, to a 3" tee and cam lock. Unfortunately we have no place to use dual 10' chambers, barely have room for what we have now. Should have pictures up next week.

cool. not enough people build large cannons. they are a ton of fun. find a local salvage yard, and get a car hood or a car door for cheap, then shoot at It and see If you can put holes in It. It is by far the most fun thing to shoot at. If you don't believe me, then try it, and you will be convinced.

P.S- use metal ammo. A 12 inch long 3/4 or 1/2 inch steel pipe pr pipe nipple wrapped in tape then lubricated with wd-40 works spectacularly.

I put one through a carhood,then cardoor,then a two layer metal table, then a 2x4, then a piece of good 3/4 inch plywood, and then a bale of hay, and 300-400 yards Into the field at the same time !!!! this shot was at 85-90 psi. At 80-120 psi (max pressure I've gone to, you cant even see the ammo flying through the air !!! It's crazy!!!

LucyInTheSky said

wtf is your problem? He was only saying yours is a huge cannon.

And that 4" valve will be more powerful than yours as it has 3" outlets.

did you even read my second to last post ? it explains everything. the valve has interchangable 3 inch porting, and has been shortened up,too.

Yea we just shot it again today. Sent quite a few tennis balls out of sight. They work pretty good if you cut a slit and fill them with rocks and sand for wait. Not sure exactly, but at 115 psi, the last one went about three tenths of a mile (measured with google earth). We'll have to find a hood or something to shoot at, should make good damage vids for the contest.

DonTheLegend wrote:...but at 115 psi...

115 PSI with those non-pressure-rated parts?! Geez, you have balls of steel (which you will need when many pieces of PVC shrapnel fly at you at high speed)!

Man, I am afraid to take my cannons above 80 PSI (and they are all pressure-rated)!