OK....I clearly recollect seeing an article on the construction of copper pipe accumulators. Can anyone direct me to it? Secondly, how does one determine the appropriate size of the accumulator? Thanks, CWebster
Not sure about the first one, but for the second one, it depends on which format. For Fast Gun, I have no idea. For Big Gun, you want 1.5 to 2 cubic inches of volume per barrel. 1.5 to 1.7 cubes for .177" and 3/16", and 2 cubes for 7/32" and 1/4". So for a 2-barrel 1/4" cannon, you would want about 4 cubic inches of air.
For fast gun, I size mine depending on application; cruisers get smaller ones (like 1/2" diameter by 2" long), battlecruisers and battleships get 3/4" by 3 or 4". Use one accumulator per cannon, with a check valve on the input side (from the regulator). I don't have a link to the tutorial, tho
Thanks Karl, that was helpful. I am indeed talking about Big Gun. I just know I saw a short pictorial article on building these things...I will continue to look. CW
Seems to me I've seen an article on the accumulator thing too, but don't remember where. If I come across it, I'll post a link.
Here is a link to what I was thinking of (I think??) probably not what you were after.. http://rcwarships.org/rcwarships/nwc_new/?category_id=27&menuaction=phpbrain.uikb.view_article&art_id=7
There is also the corresponding/older article for the same subject: http://rcwarships.org/rcwarships/nwc_new/?category_id=27&menuaction=phpbrain.uikb.view_article&art_id=5
That's a first class how-to (I like parts lists and pics I am confused about one thing that I hope the big gun gurus can help me on; how does it not chain-fire a bunch of bearings together? i.e.- what serves as an interrupter pin? I ask because eventually, I'll need to arm Nevada with big guns
For the Arizona styles (and variants) the bearings that aren't in the "loaded position" are just pushed back up the magazine a little by the CO2 blowing by, and therefore kept clear of getting into the breech until the firing valve is closed again. The magazines are just gravity feed. Cheers Jeff
My understanding of the breech mechanism is slightly different. The pin (see the first article) is set so ball in the breech and the first ball in the magazine overlap a bit. When you fire, the ball in the breech pushes the other ball out of the way, and the momentum and gas pressure push it further up the magazine. By the time it rolls back down, you have usually stopped firing (or there isn't enough gas to propel the ball out the barrel.) This is why most Indiana guns have screws in the breech, to allow the ball in the breech to be adjusted up and down if necessary.
Thanks. You basically gave a more complete answer than mine, or at least filled in the gap that I'd left off. As you mentioned, there is only room for one ball in the breech (thanks to a correctly set setpin of some variety), but when firing, the next ball cannot drop into the breech until pressure has gone back down. That part of the Indiana and the Arizona are the same. On my Indiana's, I've seen balls shoot out of the loading tubes, into the magazine proper, and then balls drop back down again during firing. The times when I've forgotten to put a pin in my loading tube, I've had a bearing fire straight up out of the magazine, so it's definitely CO2 pushing them back out of the way. In between the two answers, is one complete, and correct answer. Cheers Jeff
