SpudFiles

SEAKING9006 wrote:As long as I use strong enough fishing line, it should work.

As long as you use strong enough fishing line.... True.

I gather than that you're going low pressure and minimized accelerations? IE, deliberately low performance?

I'm going for grenade launcher rather than anti tank gun, if that's what your asking. And yeah, 25-50psi is where I normally run my cannons. That limitation is mainly based on the low capacity of my compressor, 3 gallons. As long as it will shoot out of the cannon, with a good trajectory, that's fine. If I need to bring the pressure higher, I'll just use heavier line.

yes fishing string is strong, but it just will not stand up to rapid acceleration

I would attach the rope outside the front end of the barrel, and then have the rope simply go into the barrel.
Instead of having the spool outside the barrel, why not just throw in all rope and shoot that too? No more inertia problems.

great idea here, i would love to see a prototype in action. i honestly think the line will break at the breach hole. why not use the tried and tested working model of a fishing bow. i made one a few years ago and it works great. just a good zebco 303 or something similar, not a open face reel. but it must be mounted at the muzzle on the outside.

I've drawn up the 3'rd version of the concept (2nd wasn't drawn) and I'm adding it now. In this revision, there is no breech hole. A piece of 1 1/2" with a threaded port for access will hold the spool internally. The entire barrel/tee/reel housing will all be one piece, secured to the valve with a union. A small piece of 3/4" sticking up will likely be attached to keep it straight.

Why not put that spool on the left side of the T (behind the ammo) so its fired along?
That way the projectile has to pull less on the string to accelerate it.

I may use that idea later, but I'm focusing on a simple projectile that doesn't have too terribly many aerodynamic efficiency. As it is, the cannon will have relatively low performance.

I am set to build the first prototype. All I need are fittings and a few different diameters of pipe. I can't wait to test it!

UPDATED, see first post.

UPDATED, cannon complete.