Seems like pie in the sky? Well not anymore according to this report, which suggests that Dutch engineers are exploring using lighter materials and some are pondering ideas
as radical as returning to propeller-driven planes as an eco-friendly
alternative to passenger jets.
I think any exploration is worth it innovation is going to be the only way to reduce this industry's carbon footprint, not reducing passenger numbers which is never going to happen!!!
Not pie in the sky. I designed and built a proto-type inner atmospherical Flying sphere (Flying Saucer) over 40 years ago. I have lacked the funding to take the design to full scale but it could be done. Lighter materials would definitely be a plus especially using Carbon Fiber which would surely affect the economy of the Wankel rotary engine. Paul Moller has the right power plant and has done a masterful job of maximizing its efficiency. I'd love to incorporate his engine in my craft.