Best in class? Probably not, it is a pretty large class. :) Though the gun looks very good.

Not too many possible mods,. Multiple spark gaps are a possibility. A shooting chrono would be nice.

I'm not a big fan of coax's since they have a lot of extra surface area but it does keep the overall ...

Here is a link to a short video I have made about my cannon. It doesnt go deep into details but I'm guessing experienced spudgunners will know whats goin on.

[youtube]http://www.youtube.com/watch?v=8G4g5x79x3A[/youtube]

Now it's not without it's kinks, but I'm proud of this cannon and looking for ...

Where talking about the same thing. Because you can relate the internal pressure to Work and kinetic energy, and doing the way i described it is no less accurate then the way you described how to do it. It just all depends what you know and what your looking for.

You guys are right but kinda wrong too.

Force * Distance = Work
And work is in units of energy.

Kinetic energy need to be included.

KE = (1/2)mv^2 = one half mass times velocity squared

The correct way to find the average force your gun exerts on any object down the length of the barrel ...

If I do it I want to do it right. Especially on such am expensive gun. I would go with CPU fan, Plus 2 square batteries, and a switch. I've never see one of those cad fans before though.
Are there fans small enough to fin inside a 3" chamber?

We'll while this thread is hot I'd better post this two. I have 4 guns. The big one. An awesome mapp gas metered chamber, a hair spray chamber, and a mini. The gun I use in this vid is the common hair spray gun.

Def go high quality on this one, worth it.

but we found out that the gas sinks
This is part of what the chamber fan is designed to fix. It's not exactly hard to put one in place, I think it could well be worth your time.

@mrbadexample: Big bore cannons always tend to have lowish muzzle velocities, because the forces available scale with ...

the seconds we would save by adding a fan just aren't worth the work to us right now.
It's not just seconds saved, it much improves power, efficiency and reliablity.

Power isn't a concern just yet, but if it is mapp gas will be used instead of propane. If more power is needed after that then we ...

My first question is, does anyone know of a Combustion PVC Cannon bigger than mine.
How are we defining largest combustion? This has a total volume (of both chamber and barrel) of a little over 150 litres.

Yours is, from your dimensions, a bit less than 100 litres, meaning Gort's cannon is ...

Hello, this summer I finished a PVC cannon that I believe may be the worlds largest in the category of Combustion PVC Cannon, but I'm unsure of this so that's why I came here. The barrel is 8" X 5' and the chamber is 10" X 3'. I made a video about the whole thing.

http://www.youtube.com/watch?v ...