Fol. 17v

Leonardo reuses the paper from an earlier drawing that shows the muscles of a leg, but he does not write over it, perhaps to underline the role of the limb which, according to him, provides a good part of the thrust of the flying machine.
Next to this, on the lower part of the page, are tails seen from every perspective, with text explaining the functions.
Above, an important if vague frontal vision of the flying machine, a complete drawing of which was not provided in the Codex by the Maestro.

«Se l'uccello scende a levante stando sopra il vento meridionale coll'ala destra, senza dubbio si rovescerà se non volta subito il becco a tramontana e allora il vento colpirà i palmi delle sue mani al di là del centro di gravità e si innalzerà la parte anteriore dell'uccello stesso»
(If the bird descends towards the east, remaining above the southern wind with the right wing, without a doubt it will turn over unless it immediately turns its beak to the west, and then the wind will strike the palms of his two hands on the other side of the centre of gravity and the front part of the bird itself will rise up.)

NOTE. For each page of Leonardo’s Codex we provide a brief summary, with the quotation of one that page’s most significant passages edited in modern Italian, with an English translation.

translation by Kim Williams