Since the amount of frontal surface area influences a
body's Drag Force when moving through the air, creating
a parachute that quickly inflates and remains inflated would
be helpful. An external or built-in frame can aid in this.
When a non-framed chute deploys, its inflated diameter is
only two-thirds the canopy's diameter when it is spread
out flat on the ground. Since area is related to the square
of the radius (A=Πr2), the chute's area when deployed is less
than half than when it is fully spread out. A parachute with a
frame thus has the potential to displace nearly twice the
volume of air as one with no frame.
There is a trade-off in designing a chute with a frame, however. The weight of the
parachute system with a frame will increase. This may be acceptable (when allowed by
the rules that govern the model parachute challenge), if sufficiently light-yet-strong materials are used
for building the frame.
REALITY CHECK: Parachutes that are packed into a backpack-like container make frame-based
Hang gliders, however, do utilize a frame to help the canopy maintain its wing-like shape.