I dreamt I invented / flew / swam / road a trans-medium sports transportation device last night. I think this idea came from a youtube video in which they stated that hydrogen was not toxic to breath and could be used to make a breathable air mixture like helium oxygen albeit explosive.

Here's how it worked. You had an experimental plane tube like section. The prop was driven by a very trick single cylinder motor. The piston of the motor was a metal with a high strength and curie point and there was a head built out of alternating layers of metal that would conduct a magnetic field and one that wouldn't. (yea I know wear would be high) and behind it a coil of copper wire.

The cylinder moving would convey a magnetic field to the coil or vice versa. The motor would been entirely sealed with the head exposed outside with cooling fins but the exhaust and intake would go to valving that either went to source of air and fuel and exhaust or a sealed box. In the sealed mode the air intake would also seal.

This would allow the device to act as a gasoline motor/alternator in air mode and as an electric motor in underwater mode. The head would have a third solenoid operated valve so that in electric motor mode compression is relieved.

You'd have an advanced battery pack as well and some electronics that consisted of bridge rectifier charge regulator or alternately inverter. It would probably be lithium / sulfur chemistry because nothing else could provide the necessary density. The regulator would monitor charge state and force a surfacing if too low and shut down charging if too high or battery gets too hot.

The wings would be multiple fold-able design and shaped for maximum lift as this would not be intended as a high speed device owing to power and weight balance not being ideal. They would have tensioning cables arranged to unfold and tension them for flight operation. A largish rudder and vertical stabilizer along with power modulation and a vertical winglet attached to a front steering wheel would assist in directional flight control, ground steering, and directional control on the ground in conjunction with rear rudder.

To save weight the cockpit would not be enclosed and the front wheel and rear wheels would always be extended. There would be a hydrolyzer to provide an oxygen and hydrogen atmosphere for breathing under water.

Excess hydrogen not needed for the breathing mixture could be used to inflate a balloon for buoyancy. The rudder and vertical stabilizer could also be used for dive/surface and directional control.

I don't know if material engineering could even make this all practical, but it would be a cool stunt device for an escape or invasion device in a bond movie.

Anyway, I'm posting this hear firstly for entertainment, at least If found it interesting to fly / ride / submerse in the dream, and second, so it gets on the Fediverse and by extension on Wayback Machine so if anyone does do the engineering and tries to patent it, I can claim prior art, get the patent and license it to you.