Fixed-wing flight isn't unknown to the natural world.[0] Flagella use propeller motion for propulsion.[1] Lots of animals use jets.[2] I'd consider the combu

Fixed-wing flight isn't unknown to the natural world.[0] Flagella use propeller motion for propulsion.[1] Lots of animals use jets.[2] I'd consider the combustion engine to be the most novel 'human' design with regards to aircraft propulsion -- or the way we achieve jet propulsion; that's pretty unique. [0]: https://en.wikipedia.org/wiki/List_of_soaring_birds https://en.wikipedia.org/wiki/List_of_soaring_birds [1]: https://en.wikipedia.org/wiki/Flagellum https://en.wikipedia.org/wiki/Flagellum [2]: https://en.wikipedia.org/wiki/Jet_propulsion https://en.wikipedia.org/wiki/Jet_propulsion