Curved Sprung Legs for the Flying Machine
Wedge-shaped elastic feet and retractable ladder-legs, likened to a swift that draws up its legs in flight
Leonardo designs the landing gear of his flying machine as curved, springy ladder-legs shaped to fit the operator's body. A detail of foot a shows a wedge that drives into the ground and finds no obstacle at its point, so the machine takes no damaging shock on landing, and hooks under the foot let it alight on tiptoe rather than jarring the whole body on its heels. He compares the legs to those of a swift, which cannot take off from the ground because its legs are too short, and directs that the machine be tested over water for safety. Once airborne the legs are drawn up, as shown in the second figure. Several sketches show the curved ladder-legs, the sprung foot and the double figure of the machine.
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Sprung wedge foot a that absorbs the landing shock
When the foot of ladder a strikes the ground it cannot deliver a blow harmful to the instrument, because it is a wedge that drives in and meets no obstacle at its point; this, Leonardo notes, is perfect. Hooks fitted beneath the foot make it land on tiptoe, so the frame is not jarred as it would be landing on the heels.
Retractable legs, and the example of the swift
The curved ladders perform the office of legs, and the wings may be beaten below their base. A swift set on the ground cannot rise to flight because its legs are short; once risen, it draws its legs up, and so should the machine draw its ladders up in flight. Leonardo advises testing the true instrument over water so a fall does no harm.