Simple simulation to explain recirculation in helicopters. The helicopter can be controlled using the arrow keys. The helicopter will show air movements based upon the position. If the helicopter goes near the obstacle on the right, increased airflow towards the right side of the rotor will cause a dissymmetry of lift. If not corrected, will result in the helicopter crashing and the project will stop. If the helicopter goes near the grass, a similar phenomenon will occur, but the effect will not be so prominent.