It's time to figure out the guns for my first ship I'd like to build two triple 7/32” Indiana guns. I have 4.5 inches between the inside edges of the cap rails and 4.25 inches of depth. Before I design them I'd like to find out some more about the 'tried and true' designs that are out there. 1.What is the pneumatic actuator used to open the Buna ball valve. 2.How do I choose the Buna ball size and the hole size for the valve seat. 3.Is the bearing seal the only thing that holds pressure between the valve body and the lower section of the turret? If so will any double sealed ball bearing work? If there is a good tutorial or a set of plans out there that might answer most of my questions.
i have a cad drawing of a cannon assembaly that i drew up for when i construct some it might help you
Some guys in the WWCC you may want to talk to: Ben and Dave build their own cannons and can provide advice on the bearing. Neal and Kotori build beefy torpedo cannons and can provide advice on the buna ball valve. George is working on a tight tolerance, compact torpedo cannon that might be useful for the Kreuzer P. Sparky has done some work on negative pressure canister cannons, and is working on a triple-barrel stomper cannon. The actuator is usually a Clippard MPA-3, MPA-5, or MPA-7 miniature pilot actuator. The number specifies the bore of the actuator. I'll let Kotori describe the ball valve in a bit more detail in a separate post.
Gascan has listed some good people to talk to at the next club meeting. I can draw up some diagrams and plans for you at the meeting, too. Meanwhile, take a look at these threads: http://www.rcnavalcombat.com/rcnavalcombat/forum/topic.asp?TOPIC_ID=1437 http://www.rcnavalcombat.com/rcnavalcombat/forum/topic.asp?TOPIC_ID=181 You'll find some great posts that can shed some light on the design and operation of Big Gun cannons. And now, to try and answer your questions. 1) The pneumatic actuator that opens the buna ball valve is an MPA-7. There is also an MPA-5 and MPA-3, but these are too small for your purposes. 2) I don't know of any rules of thumb for choosing a buna ball, but I do know how to pick a diameter for the valve seat. In general, you want the cross-sectional area of the air path to remain the same throughout the cannon. So the cross-sectional area of the barrels should be the same cross-sectional area as the valve seat. Since you're using 7/32" cannons, the formula is: (7/64)^2 * 3 = (valve seat diameter/2)^2 which yields an approximate diameter of 0.375. Since your barrels are not perfect 7/32" diameter, and there's a few other gizmos in there, it's a good idea to round up to 0.4375 or 0.5. To pick a ball, you just eyeball one that looks like it won't get jammed either open or closed. 3) Technically, yes, the bearing seal is the only thing that holds pressure between the valve body and the rotating magazine. However, I don't think there's any benefit to ordering specially-sealed bearings. First, it's only got to hold a pressure wave, not a continuous high pressure, and second, the hydrodynamics of the cannon make most of the air rush right past the bearing, so there's little loss even if it's not sealed. One of the first cannons I ever had (included when I bought a used scharnhorst) simply used one brass pipe stuck inside the other for a bearing, with a lip cut on the inside one to prevent the magazine from flying off. As for which bearings to use, just about any will do, as long as they don't have great gaping holes to let air out. Basically, if you can't see the balls inside the bearing, you should be OK. The WWCC is having a meeting this sunday to discuss this year's rule proposals. We can talk further about it then, and I will bring a few components to test-fit in your ship. Bring along the hull, and lets take a look.
WOW! I guess I just go to bed too early. I'm at work now and will have to wait until I get home to make sense of all of this. I just wanted to thank you guys for all the input.
it says i dont have permission to write to the file, how do you get permission? and on topic do you need a bench lathe to build a cannon or is it possible without one
Ben suggested that I buy my first set of cannons. Mainly to speed things up. I may do this. I'll check in to see what ideas they have. I'm not familiar with either of these designs. Is there any info on how they work on the web? It's too bad the Big Guns Cannons thread got so derailed. The first page was really informative any chance you guys might continue it someday?
I had seen your 'Big Gun Canons' thread. It was one of the first things I read after joining. I still need some background on how the canister, negative pressure, and stomper canons work to really follow the discussion. I was mainly worried that if I get the ball seat too big the the actuator won't have the force to open the valve. It looks like the MPA-7 has a 7/8 bore so that should be plenty to if the valve seat is 1/2 inch. I just looked in my garage. I have several sets of bearings that might work. Can you PM me the time and place? I don't think I'm getting all the club emails. I don't know if I could or would vote since I am so new, but I would be interested in knowing what changes I can expect for next years rules.
There haven't been any club emails about this. The location hasn't been set yet, but the time is set in the rulebook: the first Sunday in November. I have contacted the other club officers to find out more about this. This year there is a record-setting three rule change proposals (our lowest number ever), and the meeting will clarify them before they are sent to members to vote on (you may vote if you have paid dues this year). 1) increase battleship armament 2) eliminate ship-deployed mines 3) allow ships to carry anti-fouling gear to protect against weeds Ooooohhh! Sparkly! That photo just goes to show that you should never feed wild transports. If they get used to warships, they may become dependent or even attack. You should leave them alone and enjoy them in their natural habitat.
ok the file is up you either need solid works or edrawings viewer(free) and to note there are obviously parts missing i just wipped this up one night before work, and i have never built a cannon before so everything is a assumption and taken from what i have been reading
The guys did a good job of answering my questions in this thread... if you haven't seen it yet: http://www.rcnavalcombat.com/rcnavalcombat/forum/topic.asp?TOPIC_ID=1488
I have a lot of other photos from the Convoy vs the Entire Fleet sortie, but my resizing tool is on the fritz at the moment. Putting a bunch of full resolutions images up would take too much space. More later
Put 'em on photobucket! That's what I use for most of the images I post here. I also post combat photos to the WWCC website, but I've fallen behind there... Anyway, that's a really cool picture. My old ship getting beaten up by my new ship, as is proper. And remember, NEVER feed wild transports!
