History and Evolution of
The first known parachute design, sketched in 1495 by
Leonardo da Vinci, was a pyramid-shaped canopy supported
by wooden poles. This early design was not tested until
the 19th century, when a significant flaw was noted
-- the chute violently swayed and oscillated
during descent. This was because the air that the parachute
had passed through—called its wake—was
forming alternating eddies behind the canopy, first
on one side and then on the other. This made the canopy
begin to oscillate, which caused air inside the canopy
to "spill out" from alternating sides, making
the swaying more extreme.
The early designs lacked a vent at the top or apex
of the canopy. Adding a vent there produces a vertical
stream of air in the middle of the wake that combats
the formation of alternating eddies. Oscillations are
dampened and chute descent becomes more stable.
Parachute Design Tip: During moments
when a parachute is tipped at an angle during an oscillation,
it falls faster (and also is at risk of collapsing completely).
Reducing oscillations keeps the parachute oriented so
that it creates the most drag.