The great scientist Leonardo da Vinci envisioned a helicopter five centuries ago.
Recently scientists were able to fly a model by building the propeller he designed.
Specifically, the propeller of his helicopter was shaped like a screw.
The idea was, as its propeller spins, it pushes the air down, pushing the device up.
However, the Italian scientist was unable to construct his design since he did not have the appropriate materials. It still lacked a continuous source of energy and motion that could spin its propeller continuously.
In order to test his design, such a propeller was built and mounted on a small drone.
[Source: http://www.bigthink.com]
