Edit... This is Trinity's latest incarnation. Scroll down to see more photos.
Thank you SpudFiles!
I've been lurking in your forms for many months now, but I finally just joined so I could thank everyone here.
Go easy this is my second cannon. It's fully functional but only about 90 percent complete. Sorry about the Crummy smart phone photos and primer stains, but a little spray paint can fix that.
"Trinity" Named for its three valves.
The basics...
Valves: Three 1" Orbit Sprinkler valves ( Pneumatically triggered by 4th sprinkler valve)
Pilot: 3/4" Orbit Sprinkler valve ( Pneumatically Triggered )
Chamber: 36" pf 3" sch 40
Total air volume: 335 cubic inches
Barrel: 60" of 1.5"(1.73" id ) sdr 26 sleeved with 60" of 2" sch 80 and a 24" by 3" sch 40.
C/B: 2.37/1 with the sdr and 1.9/1 with 3" sch 40
Range: 1000+ feet with golf balls.
After starting with a compact single sprinkler valve launcher this thing is a monster. Thanks again SpudFiles And everyone here for the knowledge to build my first two cannons.
Hooked...Boomer

Edit...
A little info about the pilot valve. When I first started testing I was using a brass cross fitting and a blow gun to pilot all three valve. Well this worked it wasn't ideal. There was a slight delay( 1/10 of a sec maybe? ) before the valves opened. After changing to the sprinkler valve pilot the trigger responds instantly and with authority.