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Making toys is a great way to get more involved with the little people in your life, letting them see firsthand that build-it-yourself quality is worth pursuing. The boomerang held by my daughter, Katherine, is a good example. It's based on an Aboriginal design applied to high-quality model aircraft plywood. It only takes 20 minutes to make (plus painting time), yet it'll soar for hundreds of yards on a good throw. Backyards aren't nearly big enough. You'll need a schoolyard or ball field.
Get started with some 1/4-inch thick, five-layer hardwood plywood. Hobby shops generally carry this, but if you can't find any locally, order over the phone. I get mine from Stockade Wood and Craft Supply (800-463-0920). A single 12-inch x 12-inch piece costs $4. Price drops to just over $3 if you buy by the dozen. Don't use lower-grade, three-ply plywood. It's not strong enough and the layers contain air pockets.
Start work by drawing your boomerang. The shape isn't critical, though the cross-section of each wing is. More on this later. For now, sketch the outline of one wing onto a piece of cardboard, cut it out, then trace the shape onto your wood. Flip the cardboard over 90 degrees, draw the other wing and you'll get symmetrical results. Use a handheld jigsaw with a fine blade to cut the wood to shape.
I like boomerangs because they soar, swoop, dive and circle back to you. The secret behind this acrobatic performance is the cross-section of the wings. Looking at them end-on you'll see they're just like a simple airplane wing -- completely flat on the bottom, bluntly rounded along the leading edge, and gently tapered on the trailing edge. This generates lift and you'll need to shape both wings properly to achieve it. |
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A handheld random orbit sander spinning an 80-grit abrasive is ideal for the job. Since the boomerang is designed to spin counterclockwise, as shown in the photo, the edge directly under Katherine's eyes is a leading edge that needs to be bluntly rounded on the top face only. Remember, the bottom face of both wings must remain completely flat, at least for now. For the same reason, the edge that's nestled into Katherine's left palm also needs a blunt, leading edge treatment. Both the other edges are trailing edges. Taper them to a thin line over 1/3 of the width of each wing. You'll soon discover that the lamination layers of the plywood act as a visual guide that makes it easy to create a smooth shape with your sander. As long as you keep the exposed laminations evenly spaced, the boomerang's shape will also be smooth.
One last thing with the sander. Flip the boomerang over so the flat, undersides of the wings are exposed, then taper the ends of the wing tips to a point over the last 2 inches of their length. This reduces wing tip drag, extending flight times. Sanding lightly between coats of paint also makes a smoother surface that reduces drag even more.
The best way to throw a boomerang is with it oriented vertically, just like it's oriented here. Hold it by the bottom wing tip between your thumb and forefinger, then hurl it forward, with the blunt, leading edges of the wings leading the rotation. Into the wind is best. The boomerang will level off and fly horizontally on its own, curving back to the left as it sails in space. Depending on the angle you threw it, and the strength of the wind, the boomerang may curve back in your general direction. Whatever happens, be careful. Getting thwacked in the head by a boomerang is no fun, even if you did make the darned thing yourself. |
