system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When a helicopter’s blades start spinning, how is the helicopter able to stay on the ground? Wouldn’t the thrust generated from the blades push the helicopter off the ground?
gpt
No.

The blades are adjustable.  When they spin on the ground, they have 0˚ angle of attack, so they produce no lift.  When they are spinning, a control can increase angle of attack (for some or all of them) causing the helicopter to lift up or fly to the side.