Elenco Mechanical Butterfly - Manual (Page 9)

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It is not simply wings beating up and down; it’s a jointed motion. Whilst beating
down the wings are “flat” in order to push as much air as possible, whereas when they
are raised, they are angled so that they create less resistance. If the dragonfly, and
therefore Da Vinci’s machine, was not like this, it would not be able to fly because the
power created when the wings beat downwards, would be cancelled out when the
wings returned to their starting point.
Da Vinci wrote:
The wings must return to the top very quickly, whereas pushing backwards with the
part of the wing which pushes the air must be done at the speed required by the engine
each individual time. The movement of each of the four wings is synchronised with the
others.
Da Vinci resolved the problem by designing two pairs of wings, one for the front and
one for the back, exactly as on a dragonfly. When the wings are beating, the pairs of
wings both rotate around their main linch-pin. The energy for this movement is
provided by two spring loaded motors which drive a mechanical system made from
gearwheels, a camshaft and connecting rods which in turn allow the pairs of wings to
move alternately and in synchrony. Whilst the wings move quickly up and down
pushing the air, rods of exactly the right length fold the wings downwards ensuring
they are angled when they come back up, exactly as it happens in the animal movement.
The mechanism is very delicate and in order to make the machine work correctly it
must be very finely tuned. Furthermore, the power the motors were able to supply
would definitely not have been sufficient to lift the machine off the ground. In spite of
this, the machine plan is absolutely fascinating and, even if they are too slow, the wings
move in exactly the same way as a dragonfly’s.