In indoor helicopters, what is the main source of lift?

In indoor helicopters, the primary source of lift is derived from the rotor downwash. As the rotor blades rotate, they create a pressure difference above and below the blades. This difference causes air to be accelerated downward, resulting in what is known as downwash. The downwash generates lift according to Newton's third law, where the downward motion of air produces an upward reaction force on the helicopter.

While blade rotation contributes to the overall functioning of the rotor, including the influence on lift, it is the interaction between the rotating blades and the resulting downward movement of air that primarily produces lift in a helicopter. Wing shape pertains more to fixed-wing aircraft, where the design of the wings generates lift through airflow differences. Weight distribution is also significant for overall stability and control but does not directly create lift.