Fusion driven. A 25x1cm steam plasma tube at 4 atmospheres will release a constant 580kW of heat, from 3.79x10-19cc of regular water a year.
The physics is a bit involved. Basically the turbulence of the plasma, smashed H ions and free electrons together, to form neutrons. These bond with other ions, to cause them to fission into hydrogens.
The fission into massive heat – with a little light and X-rays – as dangerous as a beating heat – which does Molecular Nuclear Fusion.
1 Molecular Nuclear Fusion H2O+TU->He+O+E2+X-rays
Which is why you can take you pulse with a Geiger counter – as it does Molecular Nuclear Fusion with every heart beat – you do nuclear fusion, in your heart and arteries. Biologists – world experts on nuclear fusion.
In a glass tube we get the twice as thermally efficient H fission.
2 O ions 16O2++TU+4n0-> 8H++6e-+E the n0 unwind matter
3 H ions 1H++e- ->n0
1H++r n0->Er3+L+X-ray Er3=5x1018 W per atom
So lightening suggest 580kW, but the physics says 1.16MW. The Internet suggests we need 7.5kW for a personal helicopter – I would have suggested about 8kW. https://en.wikipedia.org/wiki/Robinson_R22
So we may only need a 25x1cm steam plasma to power the device.
To get one up and working in an undergraduate practical project, taking up a term. A Dr – 3 afternoons.
We drive a small turbine, to generate about 140kW. We take off 2kW to drive a little Carnot system, that returns 85% of the heat to the water boiler. This avoids the needs for a big radiator. Shedding over 1MW of heat.
This probably reduces out tube size to 10x1cm. To stop the craft, we turn down the plasma to 3.2 atmospheres, where it keep arm, without generating much power. 1KW might be a good idea.
Then to drive the craft, we increase the plasma pressure, and within 2 seconds we are air born.
This is serious power, to drive a back mounted fan. That will propel us at jet speed – with no need for a craft.
If we want to turn a conventional craft into a super sonic one, we have a ring of water nozzles, so the jet exhaust will suck water drops out. Which then boil, propelling the air craft at supersonic speed – only using a conventional amount of fuel.
We can use the heat of the exhaust, to boil off liquid, and use this steam in place of combustion products – so we fly the craft off water.
We can fly the craft into space, using a steam reservoir to fly the jet home! Once going, we need no external steam feed. Set up a Moon base – it is only 2 days away. We use large jets on the far side of the Moon, to stop it receding from the Earth.
In the Jurassic it was half the distance away.