some of our submarine models have fin planes and it would be consequent to make them working by radio control. To control them independently from the other planes you need an additional servo and a force transmission to the fin planes. In general this raises the difficulty how to get this transmission sealed and make it easy to decouple as the fin is normally mounted on deck and for getting access to the interior of the pressure hull (or the WTC) you would have to decouple the plane drive normally.
I suppose that there are already suitable solutions found by other modellers and that they are doing the job well.
For myself I have found a solution that uses magnetic coupling between the servo inside the pressure hull and the fin planes outside and I have implemented this coupling in my class 212A submarine model (see sketch and photograph, I hope the pictures will speak for themselves).
Due to the magnetic coupling it is easy to strip-off the pressure hull tube (with the conning tower on it) from the inner technics rack that contains the servo – and vice versa when reassembling the parts.
And this solution does not require any seal because transmission is provided by magnetic force just through the pressure hull tube wall. That is always tight and that is important for a submarine when “rolling in the deep”.
Maybe this might be an interesting alternative also for other submarine modellers among us.