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11iFLY | INDOOR SKYDIVING Copyright © 2018 iFLY Holdings, Inc.
The Science & Engineering of iFLY
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STEM is fun!
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STEM is used in the real world to solve problems and improve lives.
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Exciting futures in STEM await you.
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This is a Closed
Loop Vertical
Wind Tunnel.
350 HP fanX2350 HP fanX2
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Wind tunnel
testing
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What forces are acting upon a sky diver in the tunnel?
gravity
drag force
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Air
is a
fluid.
By Georgepehli (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
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0 5 10 15 20 25 30
05
00
10
00
15
00
Time(s)
Ve
rtic
al H
eig
ht (m
)
Skydiver's Height when
Falling from an Airplane
Skydiver’s Height When Falling from an Airplane
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0 5 10 15 20 25 30
-80
-60
-40
-20
0
Time(s)
Ve
locity (
m/s
)
Skydiver's Velocity when
Falling from an Airplane
Skydiver’s Velocity When Falling from an Airplane
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0 5 10 15 20 25 30
-10
-8-6
-4-2
0
Time(s)
Acce
lera
tio
n (
m/s
2)
Skydiver's Acceleration when
Falling from an Airplane
Skydiver’s Acceleration When Falling from an Airplane
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0 5 10 15 20 25 30
-10
-6-2
Drag Force Reduces
Acceleration Magnitude
Time(s)
Acce
lera
tio
n (
m/s
2)
0 5 10 15 20 25 30
-80
-40
0
Terminal Velocity Reached
with Drag Force
Time(s)
Ve
locity (
m/s
)
0 5 10 15 20 25 30
-10
-6-2
Drag Force Reduces
Acceleration Magnitude
Time(s)
Acce
lera
tio
n (
m/s
2)
0 5 10 15 20 25 30
-80
-40
0
Terminal Velocity Reached
with Drag Force
Time(s)
Ve
locity (
m/s
)
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gravity
force of air force of air
gravity
When drag force = gravity, you reach terminal velocity.
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𝐹𝑊 − 𝐹𝐷 = 𝑚𝑎
𝐹𝑊 − 𝐹𝐷 = 0
𝐹𝑊 = 𝐹𝐷
At terminal velocity:
gravity
force of air force of air
gravity
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A larger
frontal area
decreases
your velocity.
By User Alers on sv.wikipedia - Originally from sv.wikipedia
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wind
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How fast
does the air have
to move
to support
your weight ?
Engineers and scientists use mathematics to quantify physical principles…because…
we want to be able to predict what’s going to happen.
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What factors contribute to your terminal velocity?
➢Mass
➢Gravity
➢Surface Area
➢Drag
➢Air Density
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Mass
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Gravity
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Frontal Area
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Drag
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Air Density
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The experiment plan: predict your terminal velocity
𝑣 =2𝑚𝑔
𝐴𝑓𝐶𝐷𝜌
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Experimental Activity
➢ Measure yourself to find your frontal area.
➢ Go flying!
➢ During your flight, we’ll record your terminal velocity
➢ After your flight, use your measurements to predict what your terminal velocity should be.
➢ Compare your predicted velocity with your actual velocity. How close did you get?
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Now let’s go flying!
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Additional Slides
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Drag coefficients for simple objects
What would you guess the drag coefficient of your body is in
free flight?
CD
Cylinder
Flat plate
Sphere
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Fluids also have viscosity, which produces friction forces
Which type of fluid has the higher
viscosity, liquids or gases?
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Drag is the combination of friction and pressure forces
Which kind of drag do you think is more important for air flows?
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How do we know the air speed?
…with a Pitot Static Tube.
Can you find them in our wind tunnel?
…we measure it…
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Drag of an object depends on its shape, its size, and the velocity of the air stream
Shape:
3838iFLY | INDOOR SKYDIVING Copyright © 2018 iFLY Holdings, Inc.
The Science & Engineering of iFLY
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