[0xfaded]

At the front of my mind are aircraft piston engines, which haven't progressed much beyond the 60s. One notable exception are the Diamond Astro engines, which are based on mercedes blocks.

Seeing as mass scale ICE development is probably a deadend, hopefully the current state of engines will hold over until battery energy densities become viable for light aircraft (an extremely selfish desire, i admit).

[rasz]

Lack of civilian aviation development is a result of misguided regulation. "OMG stuff is dangerous, lets require expensive certification for even the most trivial things ... except for the dangerous stuff that is already in use right now" and then we end up with brand new 2021 Helicopters shipping with 70 year old Lycoming engines.