# How butterflies fly

Source:
* [YouTube](https://m.youtube.com/watch?v=FfeiU_eIB1c)
* https://www.sciencedaily.com/releases/2021/01/210121132059.htm

> Until now, the common perception has been that butterfly wings are aerodynamically inefficient, however, the researchers suggest that the opposite is actually true.

> ... researchers studied the wingbeats of freely flying butterflies during take-off in a wind tunnel.

> _During the upward stroke, the wings cup, creating an air-filled pocket between them. When the wings then collide, the air is forced out, resulting in a backward jet that propels the butterflies forward. The downward wingbeat has another function: the butterflies stay in the air and do not fall to the ground._