Wing-beating device with a screw and lead screw system

Leonardo focused on mechanical flight mainly during his first spells in Milan. This led to a number of machines, intended to be operated and leave the ground thanks solely to elaborate mechanisms and human muscular effort. The flapping-wing device shown features a screw and lead screw system, and two side stirrups, which make the wings move alternately up and down. By placing his/her feet in the stirrups, the flier powers the device through his/her thigh muscles.
Manuscript B, sheet 77 r.