Originally Posted by Viperfish
ill take 10!
ROFL, still a work in progress! will update as it goes.
imo indirect fire should have at least 1.5X the range of a regular AEG (2-3X ideally)
This mechanism for the air cannon i'm upgrading to test this, I've probably run 20-30 HPA tanks through it (via reg. set to 100+/- PSI) with barely so much as a leak. (in paint ball) BUT I NEVER run it over 120-130 PSI (ABS is rated to 250 PSI afaik). usually I ran it no higher than 100 PSI. pressure chamber has a hot water relief valve on it (rated for 150 but starts to leak around 105-110)
I was getting 300++ feet of range with "shells" from the old one (1/2:2 or 1:4 == valve:barrel diameter ratio)
at 1:3 the shell will probably be out of the barrel before the valve is completely open, lots of punch so long as I can keep the whole system pressurized to at least 75-80 PSI when shell is about to exit the barrel. if I have issues I'll actually do the volume calculations.
its just a question if a: the 1/2 tube will feed enough pressure/quick enough to the barrel (pass 3/4 and straight to 1" if that's the case) b: if the 3" x 2 foot pressure chamber is enough volume to drive a 3" barrel (next step 4" pressure chamber or longer, now 3" X 2 feet) I'll probably draw up the frame next, it would be nice to swap from "field gun" style to vehicular mounted (ATV front rack etc)
I've thought about making the pressure chamber "volume adjustable" too, so I can "tune" it for max air efficiency. I would only get about 10 shots from a 3000 PSI standard size HPA tank with the smaller 2" barrel.
I'm getting a compressor from a friend this weekend and hoping it has 12V so I can build it in with a car battery :-)
once I'm happy with the range of the cannon again I'll get back to the nuances of the shell, I need a better pressure collar system to keep the 2 halves together, the chute may need to be larger/lighter material (or "pop out" like one of those kids forts that use the plastic coils to spring open, that's a whole re-design of the shell), "nade to shell" friction will have to be tuned...and probably the biggest PITA...tuning the fins on the back to get decent spin/stabilization with out too much drag