One problem with a parachute is it gets easily stuck in the trees. A
hot air balloon shape makes an effective parachute, with less
risk to get stuck. It has a chance to glide through the branches:
The aerodynamic shape of this parachute makes you need a bigger one to
get the same fall speed. Reciprocally and advantage of the aerodynamic
shape is you get a stable and vertical fall.
The little size of the opening at the bottom makes the balloon will
inflate slowly while falling. This is a disadvantage in some
circumstances. The advantage is there is no parachute opening shock.
Also this allows to deploy several parachutes altogether with less risk
they
get mangled. That can be interesting for example for space capsules.
Such a parachute, in black and dropped from a high altitude in
sunlight, may have the time to warm up the air inside and become a hot
air balloon till sunset. That makes quite a long fall time. An
application could be for a probe in the high atmosphere of planet
Venus. Another application is a toy for summer days you inflate by
running.
I tried to make an entirely closed shape using very porous tissue to
close the bottom of the parachute. That way there would be no opening
at all hence there would be even less chance the
parachute gets stuck in the trees. But the parachute didn't inflate
correctly:
One of the many technical challenges with a parachute is to reduce the
parachute's size during the fall. That can be achieved for example by
winding up the parachute cords. The parachute size can be decreased
further by using cords latched inside the parachute. That way the
parachute can become virtually closed. Maybe that can be used after the
fall too to get the parachute back to a little shape. The hot air
balloon shape offers another way, by using an opening above the
balloon, just like real hot air balloons have. A simpler approach is to
use a slightly porous tissue for the parachute structure and a little
cord to tune the parachute opening diameter below.
