Glider with manoeuvrable tips
While sensing the difficulties involved in accomplishing the great dream of flying with man-powered machines, Leonardo started to study gliding flight. In the glider designed by him, the flier's position is conceived in such a way as to allow him to balance himself by adequately moving the lower part of his body. The wings, an imitation of the wings of bats and of large birds, are fixed in their innermost section (closest to the person) and mobile in their outer section. The latter in fact can be flexed by the flier by means of a control cable maneuvered through handles. Leonardo had developed this solution after having studied the structure of birds' wings and having observed that the inner part of their wings moved more slowly than the outer part and that, therefore, the function of this part was to sustain rather than to push forward.
Codex Atlanticus, sheet 846 v.