Elenco Great Kite - Manual (Page 9)

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Da Vinci described its dimensions, the materials with which it is to be built, its shape
and how it works; the whole notebook revolves precisely around the construction and
use of the machine. Da Vinci also imparted some “flying lessons” on how the pilot
should operate the machine. The piloting must have been complex. He would use his
hands and feet to activate ropes and could rotate, move and open and close the wings
with his own movements. Da Vinci’s design is not drawn in its entirety. We must
therefore reconstruct the indispensable parts. These include: the canvas to cover the
wings, some articulations and pulleys, and the tail, which Da Vinci knew was
indispensable for controlling the machine. Da Vinci’s instructions for building the
machine are extremely precise and even regard the materials to be used. He also
advised which ones to avoid.
On folio 7r of the Codex on Flight, he wrote:
… not one single piece of metal must be used in the construction, because this
material breaks or wears away under stress, so there is no need to complicate the job.
Da Vinci suggested using resistant leather for the joints and silk for the ropes. The
canvas could be taffeta, a very thick silk, or a linen canvas that is starched so any
holes are sealed to prevent air from passing through. Also with regards to the canvas
that would cover the wings he suggested referring to the wing membrane of a bat
since, unlike bird feathers, air does not pass through it:
Remember that your bird must only copy the bat because the membranes act as a
framework, connecting the major articulations of the wings. If you wanted to copy
the wings of feathered birds you would have to remember that they have stronger
bones and quills because they are permeable; the feathers are divided and the air
passes through them. On the other hand, the bat is held up by its membranes, which
connect everything together and are not permeable.