Tangents: Vacuum tubes can work a very long time without breaking, if they are never turned off. Wankel engines have less moving parts then piston engines and

Tangents: Vacuum tubes can work a very long time without breaking, if they are never turned off. Wankel engines have less moving parts then piston engines and can last longer because of it. Problem with Wankel engines is that they need heat and a good seal to be efficient. Stirling engines could, in theory, be superior to bout piston and Wankel engines, in efficiency and lifespan. [0] Fuel cells used to power electrical engines is yet another alternative that combines the high energy density of liquid fuel with robustness of very few moving parts. [0] https://www.youtube.com/watch?v=H_Vnxapd5fs https://www.youtube.com/watch?v=H_Vnxapd5fs