Helicopter Drop

Instructor’s Notes
Overview & Lab Experience
In this lab activity your students will cut a piece of paper and fold it into a design that twirls to the
ground the way a maple seed samara does. After the initial ooh aah, you can then very easily take this idea
and produce a myriad of variations on this basic design and study the relationship of the two halves of
the helicopter and how they affect the flight of the object. You can also draw a correlation between the
amount of air friction, the surface area of the rotors, and the speed at which the helicopter falls. All of
these things relate back to unbalanced forces.

Content Correlations and Vocabulary

Mechanics Flight
Opposing Forces Helicopters
Potential Energy Air Friction
Kinetic Energy
Speed
Gravity

Objectives
1. The student knows force and motion are
related to potential and kinetic energy. The student
is expected to identify and describe the changes in
direction, motion, and speed of an object when acted
upon by unbalanced forces.

2. The student is expected to calculate average
speed using distance and time measurements, and
measure and graph changes in motion.

Time Line
35-45 minutes

Lab Prep
For the purpose of collecting data, the kids
will drop their helicopters from 2 meters above
the floor. If you measure this distance for each lab
team and then hang a string near their lab tables it
will really speed things up. Measure 2 meters from
the floor up. Cut a piece of string, tie a paper clip
to one end, and tape the other end to the ceiling.
The paperclip will act as a weight to keep the string
straight and also serve as the starting point for the
drop.

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 Helicopter Drop
Instructor’s Notes
Safety and Clean-up Concerns
None. Let the kids use their imaginations and explore as many possibilities as time will permit.
You will be amazed at what they create.

Answers to Questions
1. Should be about .001 kg. 2. clockwise 3. counterclockwise
4. slower 5. gravity 6. air friction or drag
7. OPPOSING 8. DIFFERENT. 9. FASTER
10­—20. The answers vary with the helicopter.

Silly Story
My fourth grade science students in California did this activity, without all of the algebra, as
part of a unit on flight. The kids had a lot of fun and really enjoyed the activity. One year I had a very
social bunch and they loved to talk. All of the time. No matter what I did they would still visit with
each other after just a brief moment of silence.
So we are engaged in this lab and I am, as usual, shooshing them. And they are a little more
talkative than usual. Actually, a lot more talkative. It is driving me nuts so I stop them in the middle
of the lab and tell them that if they do not start experimenting quietly I will hand them a monster home
work assignment. There was a moment of quiet immediately followed by more yacking.
I waited until the end of the lab period and, as they were ready to go out the door, I told them
that their homework assignment, due when I saw them next week, was to take the original design and
adapt it to create 50 new helicopters. They could use different materials, add rotors, change the dimen-
sions, whatever they could dream up was fine, but the litmus test was that it had to spin to the ground
when it was dropped. And, as you would expect they stared at me for a second then started yacking
again.
I forgot about the assignment until the following week when I was outside on bus duty. I am
unloading kids from the buses when fourth grade students start pulling up to the curb and getting out of
their cars with these giant garbage bags full of something. My guess was some project for social studies
until one of the kids rolls up to me and announces, “That was the coolest homework assignment ever. I
made 70 helicopters!” It immediately occurred to me that I now had approximately 1500 helicopters to
grade. The kids came to lab that day, busting a jaw, as usual, but they were also really excited to show
me all of the designs that they had created.
The thing that was really cool about this was that there is no way that I could have dreamed up
half of the ideas that they presented. But even more amazing was that as each kid showed off his top
three designs all of the other kids were stone, cold quiet. They were attentive, engaged, and thoughtful,
and it changed the way I presented science lessons forever. Give them ownership, reward creativity,
and encourage originality, and the kids will blow you away with what they produce.

Congruent Labs
Modified Marble Races Counter Intuitive Celts Air Burst Rocket
Balloon Rocket Water Rockets Ramp It Up
Carry Me Back

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 Helicopter Drop
Lab Instructions
The Experiment
In this lab activity you will cut a piece of paper and fold it into a design that twirls to the ground
the way a maple seed does. After the initial ooh aah, you can then very easily take this idea and produce
a myriad of variations on this basic design and study the relationship of the two halves of the helicopter
and how they affect the flight of the object. You can also draw a correlation between the amount of air
friction, the surface area of the rotors, and the speed at which the helicopter falls. All of these things
relate back to unbalanced forces, as you will see.

Vocabulary & Formulas

Velocity: The rate or speed (v) at which an object moves. Measured as distance (d) divided by
time (t) .
v = d/t

Potential Energy: Potential energy is energy that is stored and ready to use. A snowfield perched
in the mountains waiting to become an avalanche has potential energy. Stretch a rubber band, wind a
spring, or fill a bike tire with air and they all have potential energy. The formula is:

PE = mgh

where:
PE = Energy (in Joules)
m = mass (in kilograms)
g = gravitational acceleration of the earth (9.8 m/sec2)
h = height above earth’s surface (in meters)

Kinetic Energy: Kinetic energy exists whenever an object that has mass is in motion with some
velocity. Everything you see moving about has kinetic energy. The kinetic energy of an object in this
case is determined using the formula:

KE = (1/2)mv2

where:
KE = Energy (in Joules)
m = mass (in kilograms)
v = velocity (in meters/sec)

Gravity: Gravity is a force pulling together all matter. The more matter an object possesses, the
more gravity. So things that have a lot of matter, such as planets, moons, and stars, pull more strongly.
In this lab the earth is tugging on your helicopter.

Air Friction: Air friction, or drag, is the force exerted on a falling object by collisions with air
molecules that slow it down. It is dependent on the mass of the object, the surface area of the wings, and
the relative turbulence in the area.
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 Helicopter Drop
Lab Instructions
Materials per Lab Team
A B 1 Pair of scissors
1 Sheet of paper
1 Ruler, 30 cm

Materials per Class

2 Meter sticks
1 Box of paper clips, small
1 Roll of string, cotton
1 Roll of masking tape
1 Digital scale or triple beam balance
1 Clock with sweep second hand

Procedure
1. Use the template on the edge of this page as your guide when you
are cutting your helicopter.

2. Cut 1.75” off the bottom of a sheet of paper. This will give you a
long, skinny rectangle. The next cut to make is along the dashed line that is
between the letters A and B. After that, make two small cuts directly above
the letters C and D.

3. Once you’ve made your

cuts, fold one of the long strips
C D (A) to the back, crease it along
the solid line, and fold the other
strip (B) toward the front. These
are the rotors of the helicopter-
like samara and, at this point, it
should look like a giant capital I
with bunny ears.

4. Fold the sides (C & D)

into the middle, just as you would
fold a legal letter. This is the body
of the helicopter.

5. The last thing to do is to fold the bottom (E) of the samara up about
half an inch. This fold helps keep everything together. A cartoon of what
E the final contraption should look like is pictured above.

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 Helicopter Drop
Lab Instructions
6. Using the digital scale or triple beam balance, weigh your helicopter. Record the mass in
kilograms on your Data sheet.

7. Assume the helicopter flying position: Stand on a chair and extend your arm with the helicopter
in the air just barely touching the paper clip hanging from the ceiling; this is 2 meters above the floor. Place
your other hand on your hip. Drop said invention from outstretched, overhead arm. Make appropriate
ooh-aah noises. If the spirit of Sir Newton is with you, your helicopter will twirl to the floor.

8. Now that the excitement has subsided, drop the helicopter again, and note whether the “rotors”
(those would be the big flaps on top of the helicopter) are spinning clockwise or counterclockwise. Record
your observations.

9. Nab the helicopter, flip the “rotors” to the opposite sides of the body, and drop it again. On
the next page, record whether the “rotors” are spinning clockwise or counterclockwise, now that they
have been reversed.

10. Point the rotors down before you start (rather than up) and drop the helicopter again. Determine
if the rotors spin faster or slower. Record your observations in the space provided.

11. Finally, note the paperclip hanging 2 meters above

the floor. Hold the helicopter at the 2 meter spot with your
rotors pointing up at 45 degree angles and release it. Record
the amount of time that it takes to hit the floor. Repeat this
experiment 3 times and record the times in the data table in
the row for Helicopter #1.

12. Snip 3 centimeters off the end of each rotor and drop
the helicopter from the 2 meter mark again and time the fall.
Make sure your rotors are pointing up toward the ceiling. Do
this a total of three times and record all three measurements
in the data table in the row for Helicopter #2.

13. Snip 3 centimeters off the end of each rotor a second

time and drop the helicopter from the 2 meter mark again and
time the fall. Do this a total of three times and record all three
measurements in the data table in the row for Helicopter #3.

14. When you are done with your experimenting

calculate the kinetic and potential energy for each helicopter.

15. Finally, create a helicopter that has rotors on the top

and bottom and bring it to your next lab period.

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 Helicopter Drop
Lab Instructions
How Come, Huh?
This is a simple exercise in air friction, which produces the unbalanced forces that you are studying.
As the helicopter falls to the floor, the air molecules push up against the blades and slow its descent. The
official term for this resistance to the movement of the helicopter is air friction or, drag. It spins because
the blades are on opposite sides, causing unbalanced forces that spin the helicopter.
When you flip-flop the rotors, the forces are still there, but
they are reversed, so the helicopter spins in the opposite direction.
If you start with the rotors pushed down, there is resistance to the
movement of the air over the rotors and it is so great that it actually
disrupts the smooth falling of the helicopter and it tumbles to the
ground.
Finally, as you shorten the blades, the surface area of the
blades is reduced. Less surface area means that there is less drag,
or friction, pushing back up on the helicopter. With less friction
the helicopter falls toward the earth more quickly. Additionally,
there is less mass to push around and less friction resisting the fall,
so the rotors spin faster. This also translates into a faster descent
to the ground, as you measured.

Extension Ideas
1. Create a helicopter that has rotors on the top and the
bottom.

2. Determine a mathematical correlation between the surface area of the rotors on the helicopter
and how fast it falls to the ground. Graph your results.

3. Make helicopters out of different kinds of materials.

4. Have a contest to see who can make a helicopter that falls to the ground at the slowest rate.

5. Design a helicopter that holds up in a good, stiff, cross-wind created by a box fan blowing air
perpendicular to the direction of the descent.

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 Helicopter Drop
Data and Observations
Name :______________________________________________ Date: __________________

Teacher: ____________________________________________ Period: _________

Observations and Data

1. The mass of my helicopter is _________ kg.

Circle the appropriate word to describe what happened during the experiments for questions
2 through 4.

2. Drop the helicopter. It spun …

clockwise counterclockwise

3. Reverse the rotors and drop your helicopter again. It spun …

clockwise counterclockwise

4. Point the rotors down and drop your helicopter, it spun …

faster slower

5. What is the name of the force pulling the helicopter downward?

______________________________

6. What is the name of the force pushing up on the helicopter as it falls?

______________________________

7. The helicopter spins because it is experiencing OPPOSING/SIMILAR forces.

8. When you flip the rotors the opposite direction, the direction of the spin changes because the
force acting on the rotors is THE SAME/DIFFERENT.

9. The shorter the rotors, the SLOWER/FASTER they spin.

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 Helicopter Drop
Data and Observations

10. Fill in the data table below as you experiment.

Trial #1 Trial #2 Trial #3 Average

Time (Seconds)
Helicopter 1
Helicopter 2
Helicopter 3

Calculations
Calculate the velocity for each helicopter by using this formula: speed (v) = distance (2 meters)÷time
(seconds). Enter the average time from the data table above into the line below for each trial.

11. Speed of Helicopter #1 = ( 2 meter)÷_________ (sec.) = __________ m per sec

12. Speed of Helicopter #2: = ( 2 meter)÷_________ (sec.) = __________ m per sec

13. Speed of Helicopter #3: = ( 2 meter)÷_________ (sec.) = __________ m per sec

14. Graph your data for these three trials on the next page.

Calculate the potential energy for each helicopter by using the formula, PE = mgh.

15. Potential energy of Helicopter #1 = ( _____ kg)(9.8 m/sec2)( 2 m) = _________ J

16. Potential energy of Helicopter #2 = ( _____ kg)(9.8 m/sec2)( 2 m) = _________ J

17. Potential energy of Helicopter #3 = ( _____ kg)(9.8 m/sec2)( 2 m) = _________ J

Calculate the kinetic energy for each helicopter by using the formula, KE = (1/2)mv2

18. Kinetic energy of Helicopter #1 =1/2 ( _____ kg)(________ m/sec) = _________ J

19. Kinetic energy of Helicopter #2 =1/2 ( _____ kg)(________ m/sec) = _________ J

20. Kinetic energy of Helicopter #3 =1/2 ( _____ kg)(________ m/sec) = _________ J

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 Helicopter Drop
Data and Observations
Using the data from the data table on the previous page, construct a bar graph. Be sure to
label the vertical axis with numbers. A title would be nice, too.
Velocity of Helicopter (meters/second)

Helicopter #1 Helicopter #2 Helicopter #3

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