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Teacher Background

What It’s About

Most students may envision boomerangs as wooden throwing sticks, but these fascinating flying devices can be made of many different materials, including metal, plastic and even paper. Some boomerangs are designed to return, but others do not. Both tools have been used for millennia.

The non-returning boomerang goes back to the Stone Age. Used as a throwing stick for hunting, it was shaped to travel long distances on a very straight flight path. Versions of the non-returning boomerang were used in Europe, Australia and Egypt, and among some western Native American tribes.

The returning boomerang was raised to a high art by the Australian Aborigines. It was used for hunting, and as a battle club, musical instrument and even fire-starter. Hunters would throw returning boomerangs near roosting birds, seeking to scare them into flight so they could be caught in nets. Hunters also would throw boomerangs through flocks of flying birds, hoping to clip a wing and bring down dinner.

Both forms of boomerang are amazing aeronautical devices, basically rotating wings curved like an airfoil. All non-returning boomerangs are straight, but the returning variety can have many designs. The classic returning boomerang has a lazy “L” shape, but some look like a question mark. Some returning boomerangs have three or four wings (like a cross). The different features determine how quickly a boomerang returns when thrown. Large, open designs tend to travel furthest, while tighter shapes and boomerangs with extra wings tend to follow shorter paths.

Several physical processes make a returning boomerang work: aerodynamic lift, gyroscopic precession, drag and gravity. The proper way to throw a boomerang is in a vertical plane, tossed slightly upward and with a rapid spin. The spin produces a gyroscopic effect that keeps the boomerang moving along its plane without flipping and fluttering. As the boomerang travels forward, the rapid spinning of its wing tips produces a strong lifting force. Because the boomerang is oriented vertically, the lift pushes sideways, causing the boomerang to turn and return to the thrower.

The forces influencing the flight of a boomerang are similar to the gyroscopic effect that keeps a bicycle upright and stable. To turn a bike, the rider merely tilts to one side or the other. This puts a sideways force on the spinning wheels, causing them to turn in the direction of the rider’s lean.

The leaning force on the boomerang is caused by an imbalance in the lift between the top and bottom wings as they spin forward through the air. The top wing moves against the airflow and produces a strong sideways lift. Simultaneously, the lower wing is moving in the same direction as the airflow, which produces a weaker sideways lift. The difference in lifting forces causes the boomerang to lean sideways. As with a bicycle wheel, the gyroscopic effect of the boomerang lean causes the boomerang to turn in a circle and return to the thrower.

Objectives and Standards

Students must answer the following question.

Will a boomerang always come back, no matter how it is thrown?

Materials and Setup

Materials per Student

• Pair of scissors

• Pencil with flat sides

• Sheet of 8.5-in. x 11-in. card stock

• Thick book

• Copy of “Finger Boomerangs” page

• Copy of “Four Wing Boomerang” page on card stock

Optional Activity: Paint Stick Boomerang

Teacher Materials

• Hot glue gun with glue

Materials per Student

• 2–4 pennies

• 1 or 2 heavy rubber bands

• 2 wooden paint sticks

• 10-cm x 10-cm square of sandpaper

• Colored markers

• Safety goggles

• Copy of “Paint Stick Boomerang” page

Setup

1. Create one set of boomerangs for demonstration. Test-fly them to practice your launch technique and to ensure the boomerangs return.

2. Make copies of the “Four Wing Boomerang” page on card stock (one per student).

3. If conducting the optional activity, obtain 48 wooden paint sticks (used to mix paint) and sandpaper (40–60 grit) from a hardware store. Cut the sandpaper into 10-cm x 10-cm squares (1 per student).

Procedure and Extensions

Time: 1–2 Sessions

What To Do

1. Ask students, Do you know what a boomerang is? What does it do? Have you ever seen one thrown, or have you thrown one yourself? Discuss the shape of airplane wings and compare them to boomerang wings. Ask, What does an airplane wing look like from the side? (Refer to the wing diagram from the activity, “Ring Wing Gliders”) Remind students of how airplane wings produce lift. Point out that boomerangs are rotating wings, similar to the blades of a helicopter or a ceiling fan.

2. Have students make finger boomerangs out of card stock paper. Use the patterns on the “Finger Boomerangs” sheet as a starting point. Review the instructions on how to launch these boomerangs as a class, and have students fly their own. Although the blades of these boomerangs are flat, they become airfoils when spinning, and generate lift.

3. Ask, Are there other boomerang shapes that will return? Have students use the rest of their card stock to design boomerangs of other shapes, cut them out, and test-fly them. Lead a class discussion of which shapes worked, which didn’t, and students’ speculation about the reasons for these outcomes.

4. Tell students they have “graduated” to a larger boomerang. Have them cut out their four-wing boomerangs. Demonstrate for students how to throw this boomerang, then have them fly theirs. Ask, Do you think there is a limit to how big you can make this kind of boomerang from card stock? If you wanted a larger boomerang, would you have to use different materials or add something to make it work? Discuss their ideas.

Optional Activity: Paint Stick Boomerang

1. Have students build more advanced wooden boomerangs from paint sticks. With this kind of boomerang, it is critical that students understand how to shape the wings, because paint sticks are much heavier than paper and must generate more lift to work. Refer to the “Paint Stick Boomerang” page for diagrams and instructions about which edges should be rounded or sloped. Caution students to be careful not to mix up the edges. OR, as a guide, mark or label the edges of the paint sticks to be sloped or rounded. Have students use sand paper to shape the stick edges. (If necessary, scissors can be used instead.)

2. When all the edges are shaped, have students assemble the boomerangs.

3. Distribute colored markers and let students decorate their boomerangs.

4. Fly the wooden boomerangs in a room with a high ceiling (like a gym) or outside, preferably when the wind is not blowing. If there is a gentle breeze, prompt students to throw the boomerangs into the wind, not with it. As always, a boomerang should be thrown in the vertical plain, not horizontally (see student sheet), and with a chopping motion that spins the boomerang as it is released. The rounded side of the boomerang should face left when held vertically, and it will fly in a counter-clockwise circle.
   
   Note: Left-handed students should hold the rounded side of the boomerang facing right, and it will curve to the right in a clockwise direction.

5. Ask students, Would a paint stick boomerang fly differently if it weighed more? If so, how? Use a small amount of hot glue to attach a couple of pennies to the undersides of the boomerang wings. Tell students the boomerang is kept in balance if the pennies are placed at the same point on each wing. (Hot-glued pennies can be removed and tested in different locations without damaging the wings.)

Wrapping Up

Lead a class discussion on how boomerangs can be improved. Ask, What can be done to make your boomerangs stay in the air longer or travel out farther? What other materials might be used to make boomerangs?

Extras

Advanced boomeranging: Teach students how to catch boomerangs. Explain that they should not try to catch a boomerang by grabbing one of its wings. Their knuckles will get banged! Instead, instruct students to wait until the boomerang is still spinning, and just about to drop the ground. They can catch a boomerang by clapping their hands together, with one under the boomerang and one above it. the wings.

Handouts and Downloads