Looking at the diagrams, the fulcrum is in the middle of the ornithopter, at the top of the fuselage. It’s there where each wing pivots as they flap up and down.

Discusses the principles of levers, a type of simple machine that helps lift heavy loads by changing the direction or magnitude of force applied. It explains how the position of the fulcrum ...

You can locate the fulcrum at one of three points: It is now in the middle location. The mechanical advantage of the lever with the fulcrum here is 1:1.