Doug, yeah, leaving them in water to see if the VP will shrink is obviously a non starter. I guess you could nip down the road an hour or two and see if you can find a Swiss Watch
Maker who could get it down to 30mm Dia. If you do find one, I will order a couple of 40mm for my tug and a further on for my trawler.
As to the Magnetic Motors, for me its about space in the model to fit enough generation capacity to meet the full load requirements.
Assuming the load current can be generated, a method of switching in or out the magnetic gen sets as the load varies will be required. I am assuming that you will need more than one unit.
Then, as you say we need a direct reversing ESC that will handle both the load and the power from the magnetic get sets as opposed to the nice smooth supply from a battery
.Big Boys Toys
like ships and rail locos have a Thyristor Bridge to do it, We could use suitable transistors or high current power micro circuits to build a DIY one.
Having said all this, is it a value solution to save the fitting of a battery
? Loads of different views and issues to weigh up for each modeller to reach there own conclusion. For now I have to much invested in batteries, not only as power sources but also as ballast!
Big Boys Toys