My last wheel was too crude. This upgrade explains a little further.
The flying saucer I drew will work based on existing technology and Corona Motor experiments. It’s irrelevant wether Aliens have visited this planet in the recent or distant past with regard to the workability of that saucer. Moreover the turbine can be driven by combustion gases and shift to internal storage by reason the NASA Space Shuttle Rocket of Werner Von Brawn vintage converts only 3 per cent burn into useful thrust. The Turbine is from 60 to 80 per cent effecient and direct shaft vibration to piezo-electric power over 90 per cent Effecient. The Corona Motor 90 per cent Effecient. 60 per cent times 90 per cent times 90 per cent has three per cent beat by a large margin. Even more it gets a substantial height and speed from atmospheric gases it does not have to carry internally Hense lighter. Nuclear power is for past orbital as an option.