Thrust testing some Lego propellers and rotor blades.
At the end I try to get a tandem helicopter build (externally powered) up in the air. Enjoy!

Tested parts:
Propeller 2 Blade 9 Diameter [2952]
https://www.bricklink.com/v2/catalog/...
Technic Rotor Blade Large with 3L Liftarm Thick and Black Rubber Tip [99013pb01]
https://www.bricklink.com/v2/catalog/...
Propeller 1 Blade 14L with Two Pin Holes and Four Axles [89509]
https://www.bricklink.com/v2/catalog/...