RC Space Battleship Yamato Construction

Growing up Star Blazers was one of my favorite cartoons.  At the time I didn't even know what anime was. I just knew I loved the "Argo" (Yamato). Technology being what is these days I can 3D print/build just about anything so its time to put my favorite boat, starship, submarine, aircraft carrier etc in the water!!

My goal is to make the Yamato and rc boat.  I originally thought about making it a working submarine but opted out because I didn't want to deal with design headaches that come with that. Plus I don't have anyplace to sail where I could see it below 3".   I am planning to add lights, remotely controlled sound and a working wave motion gun.  Obviously, not a real wave motion gun but a water shooting one.

I purchased the 3D files on Facebook and they are really good.  They just weren't designed to be a RC model.  The ship is originally designed to print in 3 large sections that glue together.  For a successful RC boat I need to be able to take part of it on and off to access electronics.  So, I need to split it up further and it was time to learn some Blender skills!

.  

Fortunately there are tons of great videos on how to do this in Blender.  After some trial and error I came up with a design that lets me take the top deck off.  I had to print the ship in more pieces but it works out great for my needs.  I also plan on having the main guns be motorized so keeping the turret holes in one piece was a must.

. 

I printed everything on my FLSUN V400 and the prints came out great!  The ship is almost 4' long in total.  Next major hurdle is/was propulsion.  I have previously done a RC conversion on a 1/350 Tamiya USS Enterprise aircraft carrier. For that I used a pair of small DC 109 motors.  On a 2S battery I never needed more that a quarter throttle to keep it at scale speed.  Anything else and it was comically fast zipping around on the water.  So I figured two of those motors should move the Yamato at a scale speed.  

This is true. The problem is propellers.  I tried four or five different 3D printed propeller designs that sprayed a lot of water and had no thrust.  I finally went to Five Below and purchased a $5 RC boat with dual props.  They worked like a champ.  My setup has the DC motors mounted in the water where the Yamato's auxillary engines go.  I modified the auxiliary engine piece to hollow out pockets for the motors and the wires. 

Originally, I was going to use a water jet like I've seen in a lot of the RC Yamato videos online.  I had problems with that. First, water jets need a hole in the boat to suck in water.  Second, it has to be appropriately scaled to provide enough thrust.  Finally, it you have to seal the intake hole and make sure there is sufficient water.  This last point was just too much.  Most of the pump designs have an RC speedboat in mind. Not a modified WWII battleship.  So, I opted to use the little DC motors underwater and keep it simple.  I even experimented with a couple of brushless motors and drive shafts coupled through the hull.  Just way to much complication.  The little DC motors aren't going to win any speed competitions but they seem perfectly fine for scale cruising.

To date I have done a couple of water tests and the DC motors using differential thrust seem to be working.  

One other note about differential thrust and ESCs.  I'm setting this up on a Jumper T16 like I did KITT because I want to use the touchscreen to control the sounds and lights.  Reverse is pretty necessary on a RC car but I figure I can do without on a boat. So, I'm using a pair of brushed RC airplane ESCs.  Couldn't find any of these waterproof.  The waterproof versions are all for boats/cars with 0 throttle in the middle.  On a traditional RC plane controller this would have the throttle in full reverse with the left stick in its usual lowered startup position.  So, airplane ESCs it is.

Right now I'm working on ballasting the boat properly. I'm probably going to glue on the wings for more stability.  I know that the Yamato would not have its wings deployed while sailing on the water. It's my boat though the wings just look cool.

I resin printed the main guns to get the most detail. I printed the barrels hollow and I'm going to try to pump water through them for a main gun firing effect.  

More updates will be forthcoming but that's where we are for now.