In fluid dynamics, Bernoulli's Equation states that an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
Wings Flap downwards. Due to inertia, there is less air above wings.
( Pressure bottom - Pressure top ) x Area of Wings is greater than Gravity
Wings Flap downwards.
The Rear of wing lags behind the Front.
The horizontal force is the source of boost.
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt.
Leonardo da Vinci sketched this device.