Cannon Design and Construction- Suggestions Welcome

Hi all, another thread I had started began to get a little derailed, so I decided to spawn this one into it's own. The original thread is here : http://www.rcnavalcombat.com/Forum/...fault.aspx
I had a requset to post some details of the cannons I have begun to build, so I'll make a few posts here with some CAD outputs, and some pictures of what I have so far. As I have begun the construction process, I've noticed several things that may not work, so some changes / remakes may be necessary. Some basic background on what these are for, what I've designed so far, built so far, and what I hope to accomplish:
I am currently building a big gun Emile Bertin, a light French cruiser, and wanted to build rotating cannons for it, mostly just to get my feet wet in the cannon building process, and of the 3 ships I am currently working on, this one is the farthest along by a long shot. I know I can put torpedos on this ship, but again, I want to build some cannons, I may try to squeeze torpedos in too, if there is room, but that looks like a longshot. I may also dual purpose it so I can run cannons or torpedos if room isn't sufficent for both.
The cannon is based on the typical big gun Indiana cannon, with just some minor differences to try to keep the height of the cannon to a minimum, as well as try to keep the weight fairly low.
I have begun building two different diameters of cannon, 2-1/2" dia, and 2" dia.the 2-1/2 for the forward batteries, and the 2" for the rear. I know they won't hold much ammo, but again, it's an exercise in learning and experimentation.
There have been numerous compromises (and mistakes) to get where I am now, and again, i will probably have to re-do some of it once I get to a point where I can do some actual testing
Everyones thoughts and suggestions are welcome, as well as requested
I will try to post updates as things progress

 

Here is a Cad Section View. It's a bit difficult to decipher all the parts it if you don't know what you are looking at.
The manifold, magazine sleeve, and breech plate are all seperate pieces. The colors got a little washed out during all the file outputs, conversions,, and resizing, but I'll try to name some of the parts by color. I will sort of start at the bottom and work up. I'll start to post pics of the pieces as I get them made, and that will clear up a lot.
Yellow= Copper Accumulator
Dark Blue = Brass Adapter, Soldered to Accumulator, Threaded to Ball Valve Body
Magenta1 = -019 O-Ring
Red1 = PVC Ball Valve Body
Bright Green - Ball Valve Assy, Not all Parts Shown
White1 = Aluminum Rotation Bushing
Medium Blue = Aluminum Manifold
Magenta2 = Delrin Breech Plate
White2 = Aluminum Magazine Sleeve
Dark Green = Polycarbonate Cover Plate
Red2 = 4-40 Stainless Bolts
Not Shown - Brass Riser Tubes That Will Look Basically Like An Upside Dowm Flanged Bushing, Inserted Up Through the Bottom Of the Breech Plate - There are some dashed lines that roughly depict the concept in the breech plate.

 

Side view of the rotation bushing. The bottom is threaded to screw into the ball valve body.

 

Top of rotation bushing. I broached a hex in it to tighten it with an allen wrench.

 

2" manifold on left, 2-1/2" manifold on right. All holes will be tapped 4-40

 

2-1/2" single row ammo magazine on left. 2" single row ammo magazine middle, 2" double row magazine on right. I also have double row ammo mags for the 2-1/2. I wasn't sure if there would be room for single row or double row mags, or how well they would work, so i made both. In the pic, only the 2-1/2" is drilled, the rest are yet to be done.

 

Rotation bushing in bottom of 2-1/2" manifold with magazine sleeve setting on top. It's a little hard to see, but the delrin breech plate will be captive in a counterbore in the magazine sleeve, and will be compressed on top of a ridge on top of the manifold.

 

Side view of the 2" assy. There is a radius groove near my thumb that will serve as a pully for an o-ring for rotation. I think Its still going to be too tall to fit in the rear of the ship once the ball valve body and accumulator are on

 

I have actually finished and tested these quite a while ago, but I forgot about the build documentation I had started here. They work fairly well with 2 problems.

1) As I expected, they fire a little weak. They had no problems penetrating 2" of foam @ 125psi with the first barrels I had on them. I noticed a big gun rule from one of the clubs that stated the barrels had to be scale length, so when I cut them down the power plummeted. From all the builds I have seen, I don't really recall ever seeing a barrel that was only about 1-1/2 inches long though. Seems this may not be a widespread rule??

2) After about 50 or salvos the sleeve type rotation bushing started to sieze up making rotation very difficult. It seems maybe dirty air was forcing contaminants between the walls??

None the less, I would finish the write up here if there was any interest in it, I sort of forgot about this thread since it didn't seem to generate any interest.

 

Here is a pic of the completed unit.

 

Another view:

 

If anyone is interested in seeing any of the individual components just ask an d I will throw up some more pics. I may try to post some of the breech plates and ball valve assembly just because I enjoy torturing you guys by indirectly forcing you to look at stuff

 

Will do. I probably have the 3d solidworks file floating around I could scale up to the 5/8 ball for bigger cannons if you want it. I could also save it as a .stl file or another file type as well. I have 2d drawings also, I think. It will be tonight or this weekend before I can get to the camera.

 

Cool! I will try to find it. With the 3d you should at least get a good idea of the inner workings. How did you model the prop you made? It looked great!

 

On to the breech plates. Here they are in all thier glory in various stages of completion. As you can see, the barrel risers press in from the bottom, with a flange on the end seating in a counterbore on the bottom of the breech plates. This was done to insure there was no chance of them ever coming loose and blowing out of the breech plate. After all the barrel risers are pressed in, the angled holes are drilled through the breech plate and into the risers.

 

How does one drill the holes accuurately???? Build a fixture.

 

The risers slide into the holes on the fixture , the fixture is set on the angle milled on the end on the drill press and drill away. Perfect repeatable results every time. (The part has to be clamped to the fixture before drilling!)