Introduction
Boomerangs are amazing! What seems to be a simple curved bit of wood can be thrown away from you and then come right back and land in your hand. Boomerangs use many laws of physics in their motion including inertia, Bernoulli's effect, gyroscopic precession, gyroscopic stability and Newton's laws of motion. They are sensitive to their size, shape and aerodynamic profile, as well as wind and rising thermals.
However, it is not very difficult to make a quality boomerang that can be thrown in such a way that it will be catchable almost every time. You don't need to know about physics. You don't even need to know how changes in the boomerang produce different flight patterns. Just so long as you can tell if a boomerang is not coming back, you can tune the boomerang so that it does.
Photo further down the page...
Carving your boomerang
Traditionally, boomerangs were made with the junction between the trunk of a tree and a major root, giving the required curvature of about 95-110 degrees. Nowadays, you can buy high quality plywood which can largely withstand the stresses put upon it by boomerang crash landings. This material is readily available in DIY outlets, and it is easy to cut and shape.
Normally 5/6mm 5-ply plywood is used. Sketch your pattern onto the wood and cut it out with a jigsaw, coping saw or bandsaw. Form the aerofoils on each wing (the curved surface that gives the wings lift) using rasps, files or planes - always working towards the edge to avoid splinters. When you are sure the aerofoils are at the correct curvature, use sandpaper to smooth out any sharp lines and to leave a low drag surface. A rough surface may affect the boomerangs flight pattern, making it less controllable and responsive.
Shapes
You can make a boomerang any shape you like and, in the right conditions, it will probably come back to you. But to get the best performance, it is a good idea to use a tried-and-tested design. Those featured on this page are the traditional Aboriginal V-shaped boomerang , and the Omega . I am not an expert on boomerangs, and I have only made several V-shaped and one Omega boomerang, but for the beginner, I would not hesitate in recommending the Omega design. The one of these that I have made is very impressive in flight, spinning in a very large arc in front of me and then hovering down into my hands. I have caught it 10 times in half an hour only a couple of days after making it.
Photographs of my painted Omega boomerang and a large V-shaped boomerang:
Front and back (
Photo down the post) views of both of them, with a 15cm (6 inch) ruler shown for size comparison. The V-shaped boomerang shown here is very heavy and does not return properly. It's good fun to throw because it looks so big in the air. It was broken on one arm when I brought it into school and it repeatedly landed vertically, bouncing off the ground rather hard. I repaired it with epoxy resin glue with fibreglass tape reinforcement.
Original Aboriginal V-shaped boomerang
Sketch the diagram opposite onto your piece of plywood and cut it out as stated above. Curve the aerofoil (wing profile) as shown in the inset, adding a significant undercut to the leading edge of each wing (the dark patches in the diagram).
http://pnu-club.com/imported/mising.jpg When you have finished the carving, check your new boomerang for 'dihedral flex'. This simply means how much the ends stick up if you set the boomerang flat on a table. The correct flex for this type of boomerang is about 3-5mm at the tips. Your piece of wood probably was not originally curved like this so you will need to bend it into its new position. Hold one wing over a steaming kettle or other safe heat source for about 10 seconds, moving it constantly. Quickly clamp the wood into its new position using offcuts to lift up the tip. It takes about 5 minutes for the wood to cool down again and 'set', after which time the other wing tip will have to be bent. Check your boomerang again for any twisting of the wings. They should be completely flat (except for the dihedral flex) and if they aren't, fix them in the same way as for the wing tips.
After all the correcting has been done, smooth off all the edges and the entire surface with sandpaper, starting at 80 or 100 grit and finishing with 250 grit. For a super streamlined finish, use 400 grit sandpaper. You may then want to paint or varnish the boomerang, but beware - this can add a lot of unnecessary weight to it, reducing performance, or at least changing it from what it should be. Use two coats maximum, and sand well between each coat. A thin layer of varnish over paint will give it more wear resistance.
Omega boomerang
The Omega is an improvement on the original V-shape for better handling in the wind.
http://pnu-club.com/imported/mising.jpg The twisted ends also make the boomerang spin slower than the V-shaped, so that catching is safer. One major disadvantage with this design is its tendency to break in the middle (dashed line on diagram) after only light crashes. This is due to the extended arms, which cause more leverage, and therefore force, to be directed at the apex of the curve. It might be a good idea to widen the wing around the dashed line, to give it extra strength.
As before, sketch the diagram opposite onto plywood and cut it out. Notice that the aerofoil on the Omega boomerang is less curved than the V-shaped design. This leaves more of the wood at full thickness. Remember to undercut the dark areas. Check for dihedral flex and twisting as before, correcting any error in the wood with steam or heat.
Finish with various grades of sandpaper and decorate if you like remembering that any paint will add weight to the boomerang.
Throwing your boomerang
There are a number of important points to bear in mind when throwing a boomerang, which all work together to achieve the desired effect.
