I want to rebuild my air reservoir for my twin sterns. I was a planning on using 3/4" copper tubing but am unsure of the length. Should I also make a reservoir for each gun or make one big one and then feed each gun from the one reservoir?
You may like to take a look at my Bismarck page for inspiration. https://www.scrapcombatships.com/commodore/warships/bismarck.html I will say that the tanks in my Bismarck are probably overkill - 3/4" pipe about 3" long should be more than sufficient. But as some have said, "Nothing exceeds like excess". Also, given you'll only be running duals, the simple fact of the matter is that if you put a splitter on the regulator and run a separate 1/4" hose from the regulator to the solenoids, that will probably be sufficient volume to make you happy. Which is to say: A lot of what you see are relics from a past where we were using less optimal gases, and regulators which did not keep up with demand effectively.
I got about 10” (could make it 12”) between the solenoids and the regulator. Do you think that length of hose would be long enough?
I would recommend tanks. I had duels setup on a BC reg with no tanks and the results were not all they could be even with lengths of hose. I use spent 16g capsules as tanks.
On all the boats I've ever accumulator tanked, you ideally want one tank per gun with check valves so the guns don't rob each other. Without check valves, the system is going to "share" regardless of what you do. I'll let others chime in, but this has been my methodology.
Some variation of this MJCV-1AB You can get them in different gender combinations for your specific application, helps cut down on the number of fittings required. I used to buy them with clippard's own AVT series air volume tanks for accumulators, they had female threads built in, so you could get a Female -> Male check valve that would thread right in and your air fitting would thread right into the input side of the check valve...made a very clean setup.
Alright, Im going with tanks. So back to my original question. I was thinking 3/4" diameter but it seems like 1/2" would be fine. What length should I go for? Or what is the math calculation to figure out the length?
You're looking for the internal volume of a cylinder. Volume of a Cylinder Calculator I used 2 cubic inch per cannon, I think @Kevin P. has a specific size he normally goes for too.
I'm no math expert, but that seems roughly correct? If the calculator says its good lol I just did the math on my own and got roughly that.
I tried working backwards and got a different answer. Not sure why... 2 = H * Pi * (0.75/2)^2 This gave me a height of 4.5 which is very different than the calculator.
You entered diameter instead of radius (0.375). I usually used 1 cubic inch per gun, which comes out to 2-2.5” long with 3/4” ID. here’s a link to the clippard tanks https://www.airlinehyd.com/product/CLIPPARD-AVT-12-1/1302725 In the past, when considering the costs for pipe, end caps, fittings, effort/leaks, the clippard tanks were a better choice for me
Ahh yes leaks. Soldered tanks give the gift of emergency torchwork at Nats. Experienced several times over the years.
don't forget to consider where the air accumulator tanks will be placed. 2cu.in. is an excellent target size if you have the space and weight available. The ones on my predreads ended up somewhat smaller due to size limitations.
