What Performance To Observe
This movie shows tech ed students' final parachute designs.
Pay close attention to the flight path of the different
chutes. Notice whether the canopy is stable or not,
and very importantly, whether it is fully inflated
throughout its fall.
Everyone can tell when there is catastrophic failure in
a design: the car's brakes don't work when you put your
foot to the pedal, a door handle spins freely instead of
opening the door, or a parachute collapses and falls like
a rock. Getting students to notice more subtle problems
with their parachutes is a difficult yet worthwhile goal.
One such problem involves the canopy alternating between
being fully inflated and partly deflated. Getting them to
reason about the cause-effect relationships
between their parachutes' features and performance is an
ultimate learning goal since students would then be doing
informed designing rather than random trial-and-error
Here are some parachute performance criteria that students can focus
on in their investigations:
Time of Descent -- This is the main measure of the
model parachutes mentioned in the LBD's
design brief. However, students can focus so much on their stopwatch that
they miss cues about their parachute performance that they should try to alter by changing the design.
Flight Path -- Does the model parachute fall
straight down, at an angle, or oscillat while descending?
Minimizing or avoiding oscillating improved the chute's
Inflated Canopy Does the canopy remain fully
inflated, or does it sometimes partial or fully collapse? Once
inflated, the chute should stay inflated.
Stability Does the canopy remain
balanced during descent, does it list to one side, flip
over or oscillate while descending? Stable, even travel
downward is better.