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Boomerangs, or "booms" as they are
called by enthusiasts, are curved sticks of wood or plastic
that either return to the thrower or travel in straight
paths for long distances. Although the Australian Aborigines
are generally credited with inventing the returning kind of
boomerang more than 10,000 years ago, many cultures,
including Egyptians, Hopi Indians, people in southern India,
and people in Africa, Polynesia, and northern Europe, have
used the non-returning kind as hunting sticks and as combat
weapons.
For thousands of years boomerang
design and performance have remained relatively constant.
Recently, however, modern aerodynamics research, engineering
studies, and computer simulation technology have led to
design changes that have increased boomerang performance
dramatically. While conventional boomerangs may return in
flight for 10-15 seconds, new boomerangs have remained aloft
for nearly three minutes. Drawing upon existing NASA
low-speed airfoil research, designers have employed
computers to subtly alter airfoil cross-sections to maximize
lift while minimizing drag. Performance improvements have
led to the creation of international boomerang flight
competitions that include events in accuracy, distance,
catching, two-boomerang juggling, and maximum time aloft
(MTA).
Many middle and secondary schools have
bicycle wheel gyroscopes for use in physical science and
physics classes. Inquire if one is available for your use-
If not, a small gyroscope can be substituted. Small
gyroscopes can be obtained at toy and museum shops.
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Lesson Outline
1. Discuss the role engineers play in solving problems and
in the development of new and improved products.
2. Talk about the history of boomerangs as a tool for
hunting and protection. Permit the students to observe the
airfoil shape of a wooden or plastic boomerang. If feasible,
take the students outside and demonstrate how the boomerang
works. Be sure to follow the instructions that come with the
boomerang and try it several times before the lesson. If it
is not possible to go outside, throw a four-wing boomerang
to show how it returns to the thrower. (Refer to the plans
for constructing the four-wing boomerang later in this
activity.)
3. Demonstrate how aerodynamic lift can be achieved by
blowing over the upper surface of a piece of paper held at
one end. Compare the side view curve of the paper in this
demonstration with the side view of the boomerang
airfoil.
4. Ask the students why the boomerang curves back to the
thrower. Illustrate this effect with the bicycle wheel
gyroscope and turntable. Place a volunteer student on the
turntable and give the student the bicycle wheel gyroscope
to hold. Spin the wheel and ask the student to tilt the
handles. The torque produced will be translated by the
gyroscope into precession that will cause the student and
wheel to turn in a circle. (If a small gyroscope is used,
suspend one end of the gyroscope's axle with a string. The
gyroscope will precess in a circle.)
5. Distribute paper boomerang construction supplies and have
each student make and fly a four-wing paper boomerang.
Discuss how the boomerang might be changed to improve its
performance. Improvements might include MTA, distance, and
unproved aerobatics. Using the remainder of the supplies,
have the students construct and test their ideas for
improved boomerangs. Relate this activity to the work of
engineers.
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Grade Level:
This lesson is designed for middle to
junior high school science students. The lesson can be
adapted for high school students by increasing the detail
provided on the aerodynamics of boomerang flight.
Boomerangs are thrown in a vertical
plane towards an imaginary spot that is about 10 meters away
and about 5 meters above the ground. As the boomerang flies
in that direction, gyroscopic motion and drag effects cause
the boomerang to circle and reorient itself to a horizontal
plane. Torque that leads to cession is produced by the
boomerang's spin and its forward motion through the air. The
upper blade of the boomerang has a greater relative wind
speed than the lower blade. This increases lift for the
upper blade and reduces lift for the lower blade. The
difference in lift produces torque.
Objectives:
1. To demonstrate how scientific
principles relating to force and motion combine to cause a
boomerang to return in flight.
2. To apply the methods of engineering
to improve the performance of boomerangs.
Materials
• Stiff paper (such as used file
folders)
• Boomerang patterns
• Pencils
• Rulers
• Scissors
• Drawing compasses
• Books (for launching ramps)
• Commercial boomerang (available from many sport, toy,
or museum shops)
• Bicycle wheel gyroscope, turntable or swivel
chair.
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For Further Information
Explaining all of the complexities of
the flight of a boomerang is beyond the scope of this brief
activity write-up. The resources below will provide you with
technical details on boomerang Eight including the important
topic of how relative wind direction results in gyroscopic
precession.
Haggerty, 1 (1992), NASA Spinoff 1992,
NP-201, pp. 50-53. (Describes current research and how
engineering techniques are employed.)
Hess, F. (1969), "The Aerodynamics of Boomerangs'",
Scientific American, November, pp. 124-36. (Detailed
description of how a boomerang works.)
Mason, R (1937), Boomerangs: How to Make and Throw
Them, Dover Publications, New York. (How to make and
throw boomerangs.)
Musgrove P. (1974), "Many Happy Returns," New
Scientist, January 24, pp. 186-89. (Discussion of
returning and nonreturning boomerangs)
Ruhe, R (1977), Many Happy Returns-The Art and Sport of
Boomeranging, Viking, New York. (Boomerang history and
making and drawing instructions.)
Four Wing Paper Boomerang
1. Cut out the pattern for the boomerang trace it onto one
half of a used manila folder.
2. Cut out the boomerang from the file folder.
3. Fly the boomerang by holding one wing of the boomerang
between your thumb and index finger. Keeping the boomerang
vertical, impart a spinning motion to the boomerang as you
throw it straight forward. The boomerang will travel
straight out from you a meter or two, circle, and come back.
By the time it returns, it will be spinning on a level plane
Catch the boomerang by clapping it between your hands or by
thrusting your finger into the hole.
4. Try throwing the boomerang horizontally and observe its
flight. Warp the boomerang's wings to see what effect the
curvature has on the flight.
This activity was
provided by NASA Johnson Space Center Houston,
Houston, Texas 77058
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