Here is my first submarine, scratch built 1:40 Scale Type 2D.
I found on researching the Type 2 boats that U-141 had the 8 dark stripes as camouflage,
and had a devil riding a torpedo as the emblem on the corning tower.
The hull is a one off, balsa/bass wood covered with 5 layers fiberglass cloth and epoxy resin.
I then opened up the boat at the waterline and took out all the wood etc.
The boat is powered with a single 6 volt 4.5 amp hr lead acid battery, gives me about an hour and a half.
Dual geared Aeronaut 6 volt motors provide sufficient power for the sub.
I have used the simplest system possible, where I use a 6 volt air pump
drawing air in from the periscope into the ballast tank to bring the boat up.
Trick is to have the periscope above the water. The pump can handle air and water- no problem
Pumps can be had from Caswell Plating.
I have a 4" dia 4" long lexan ballast tank where I have installed a propel failsafe back up system.
The boat runs beautifully!