How a Kite Steers by Twisting Its Tail
The tail likened to a ship's rudder; the bird rights itself against a gust
Leonardo describes how a kite descending head-downward through the air must twist its tail in the direction opposite to the turn it intends, then twist it rapidly toward the desired side, so that the bird turns as much as the tail does, like a ship steered by its rudder but in the contrary motion. A second observation explains that when the wind threatens to flip the bird over backwards, it draws the shoulders of its wings together, shifting weight forward so the heavier front descends first, and spreads and lowers its tail. The page carries a schematic bird sketched at the lower right and a small drawing near the top.
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The kite turns by twisting its tail, like a rudder
A descending kite, boring through the air head downward, must first twist its tail opposite to the intended turn, then rapidly the other way. The bird turns as much as the tail turns, exactly as a ship follows its rudder, but in the contrary motion.
Righting the body against a backward gust
When a wind is about to throw the bird over backwards, it pulls the shoulders of its wings together so that the weight grows greater in front than before. The heavier front part then descends first, and the bird additionally spreads and bends its tail downward.
Schematic bird in flight
A rapidly drawn bird, its wings and tail reduced to a few crossing lines, is sketched at the lower right of the folio, with a smaller drawing near the upper margin. They illustrate the tail-steering and balancing described in the text.