For my 1:96 Gustav V build I am planning to arm the 6" secondaries with Arizona cannons. Assuming a MJV-2 + accumulator for each barrel, how large of an accumulator should I need? Would one cubic inch be enough to fire a BB without a fast-gun style o-ring?
A friend of mine ran an experiment with different size accumulators on an Arizona cannon. He found a sweet spot between 1.5 and 2 cu. inches. Any smaller required a large increase in operating pressure, any larger didn't provide significant benefit. I like the clipboard MAT- 2 tanks. He once soldered some .5 inch copper pipe to make 2 cu. Inch accumulator to make a compact quad for his Normandie, but the small diameter limited the flow and raised the required pressure.
Was the 1.5 - 2.0 cubic inch the accumulator size for a single barrel? Also what was the caliper of the round? I'm guessing BBs?
I remember that experiment. Yes, it was 1.5 to 2 cu.in. per barrel, using the standard one MJV-2 and accumulator per barrel. Setups involving multiple barrels per MJV/accumulator combo are possible but difficult and inefficient. The exact volume you'll need is dependent on the length and blow-by of your barrels. Short barrels don't benefit from larger accumulators, so if you've got short barrels you'd better have tight tolerance barrel material. Long barrels generally require a larger barrel, due to pressure drops from smaller accumulators, so if you've got long barrels then err on the large size. I have had great success using 1/4" OD steel brake line barrels, the longer the better, with 2cu.in. accumulators.
