Energy efficient fixed-wing Foldable Rotary Origami Wing drone can change its wingspan during flight

https://newatlas.com/drones/frow-monocopter-drone-adjustable-wingspan/

"squeezes through narrow spaces or drop like falcon by reducing wingspan while flying... wings provide much larger lift surface enhancing energy efficiency... vertical takeoff and landing flying by horizontally spinning entire body, inspired by samara-type maple tree seed... 2 samara-inspired balsa wood wings joined in middle by electronics-equipped hub... telescoping carbon fiber rod runs wings' length. At the end of each wing is a motor/propeller... use wing flaps to steer... bypass hazardous weather, evade pursuing aircraft"

Related: World's heaviest soaring bird inspires wind power design
https://techxplore.com/news/2024-06-world-heaviest-soaring-bird-power.html