Rough Out Your Boomerang
Once you have your wood and a pattern, you’ll need to gather the tools. You need some sort of saw that can cut curves, such as a band saw, coping saw or bowsaw. To smooth the shape and thin the edges of your boomerang you need files and sandpaper. A spindle sander is nice to have, but it is not required.
If you are going to make several boomerangs in one shape, I recommend you make a pattern. We use paper bags, poster board or thin plastic sheeting.
Transfer the boomerang’s shape to the wood blank. Then cut the shape out with your saw. I use this opportunity to teach the physics students how to use a band saw safely. Many students have never used power tools and this was a great way to introduce their safe use.
I survey my students about their experiences with the tools, and here’s what one female student, Lo Struga, had to say about the band saw: “It felt like the first time I heard the Beatles, it was amazing.”
Once the shape of the boomerang is sawn out, you can refine its outline with a spindle sander or files and sandpaper.
Shaping the Airfoil
Now you need to make some important decisions. Like golf clubs, boomerangs are “handed.” How the boomerang’s airfoil is laid out and shaped depends on whether the person who is going to throw the boomerang is right-handed or left-handed.
The illustration below shows the airfoil shape of a right-handed boomerang. For a left-handed boomerang, you simply reverse the airfoil shape.
First mark the top of the boomerang. As with airplane wings, the airfoils on a boomerang have a leading and a trailing edge. The leading edge is a quarter-round shape and the trailing edge tapers off the top of the boomerang like the cross-section of a typical airplane wing. Mark the two leading edges and the two trailing edges so you do not file them incorrectly (a common mistake my students make). The bottom face of the wing is completely flat.
Lay out the leading and trailing edges of the wings based on which hand will do the throwing. A marking gauge can be used for this (or the old trick of holding a finger against the edge). Mark in on the top the distance that the contour retreats back from the boomerang’s edge to its top surface.
The quarter-round shape generally extends about 1/4″ from the edge, while the trailing edge extends about 1″ to 1 1/2″ into the material. Note that you only have to shape one face of the plywood. The other face is left flat. See the illustration below to understand how the airfoil shape looks on a simple “V”-shaped boomerang. Note how the leading edge and trailing edge change along the length of the boomerang.
Shape the airfoil with rasps, files and sandpaper. There are a variety of rasps available out there. We use Nicholson cabinetmakers No. 49 and 50 cabinet rasps. These tools fascinated the students and they understood their importance to the whole process.
“The files (and rasps) were indeed important in the success of our boomerangs because the files sculpted the airfoils,” Drew Jarvis commented.
And Whitney Regalski added: “Without files, the shape I was shooting for would never have been accomplished.”
A boomerang is actually a flying rotating rotor, like on a helicopter. The airfoil shape needs to be consistent, and this is where the plys in plywood help in the design of the project. As the glue lines appear from the plys it is easy to observe the progress when shaping of the airfoils.
The optional finishing touch to shaping the airfoil is to slightly bevel the back edge of the wing (if you wish). Or, another option is to make some test throws first and see if your boomerang is making a complete turn. If it is not, then file a slight back bevel on the flat face of the leading edge.
Before you decorate your boomerang, you should take it for a test spin because you might want to refine its airfoil.
When teaching students to throw a boomerang, we start by using example boomerangs made with paper and cardboard in the classroom.
Throwing requires a little practice, so it is worth the time to make a few quick cardboard practice boomerangs. Cereal boxes are a great raw material for this. You can make a quick cardboard boomerang using two strips of cardboard approximately 1″ wide and 8″ to 10″ long. Use hot-melt glue to form them into the shape of a plus sign. Put a gentle upward curl on the four blades and throw using the same techniques described below for throwing wooden boomerangs.
The throwing technique has a few key components, regardless of the material. Pinch the boomerang between your thumb and index finger and hold it over your head. Your thumb grasps the airfoil shape. The index finger is against the flat face of the boomerang.
Now hold your arm perfectly vertical. Before you throw, you need to tilt your arm 10° to 20° away from your body. This is called the “layover angle.” See the illustration on the next page for what this looks like.
The throwing motion employs a lot of wrist action to generate the necessary spin around the center of mass of the thrown wing. Throw the boomerang at an angle of 45° from the front of the body. (That’s with straight out in front being 0° and arms held straight out at the sides being 90°.) The angles are guidelines to get you started in the right direction. Do not be afraid to experiment with the throwing angles.
When throwing a boomerang outside, the wind should be light and blowing straight into your face. The throw is still 45° from the front. Aim for a point about 10° above the horizon. This will send the boomerang flying. See the illustrations on the next page for details.
One of the important reasons to make indoor boomerangs before making wood ones is to learn the throwing motion. Indoors, the flight patterns are smaller, and the feedback for good and poor throws and working designs occurs quickly. The cardboard ’rangs are quite harmless if they hit someone, too.
Once everyone is able to prove that they can throw a boomerang and not a “stick” or “kylie” (as a non-returning boomerang is called in Australia), then it is time to find a place outside to throw your wooden version.
Find a Space to Throw
The larger the throwing area the better, especially when learning to throw. Parks are areas worth scouting. A football or soccer field is a good-size space to start with. There is less chance of losing a boomerang if the area is very large. Do not throw in an area where there are children, pets, cars or structures that may get in the way.
After five years of teaching physics students to make and throw boomerangs, there have been a few surprises. One surprise is just how well the boomerangs fly. The other shock is just how much the students enjoy the entire process. They carry their boomerangs around the school and even trade boomerangs with one another.
And a few times every year some students will bring some boomerangs to class that they didn’t make at school. Yup. The students have been at home making boomerangs with their parents. One female student said that she didn’t have any interest in her dad’s shop until they made a boomerang together. In several cases, the student’s parents became so interested in the boomerangs that once the kids showed their parents (and even grandparents) how to make them, they would make boomerangs on their own. PW
HOW TO THROW A BOOMERANG
Don’t throw into the wind. Aim at 45° away from the wind’s direction.
Where to aim. Throw the boomerang at about 10° above the horizon with a flick of your wrist to set it spinning.
Tilt your arm. Angle your forearm away from your head (layover) to return the boomerang on your opposite side. If it passes too far away, hold your forearm closer to vertical when you throw.
Trevor is a physics teacher at Troy High School. He was introduced to woodworking in middle school woodshop. He now creates furniture pieces and wood turnings in his home workshop. Smith also teaches various woodworking skills and project classes at the Woodcraft store near his home in Sterling Heights, Mich.