Boomerang is a simple curved piece of wood which can do wonders it fly like an air-plane and come back in the the hand of the thrower. The boomerang becomes a weapon when in need and becomes a sport when ever you like it. 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, you don't need to be a physics expert to make one. All you need to do is to make your boomerang in such a way that it comes back. 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 throw it.

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. But you can buy high quality plywood which can largely withstand the stresses put upon it by boomerang crash landings.

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

Sketch the diagram opposite onto your piece of plywood and cut it out accordingly. 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). 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.

The Omega boomerang is a revised or a improved design of the original V-shape for better handling in the wind. The twisted ends also make the boomerang spin slower than the V-shaped, so that catching is safer. 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.

A major disadvantage with this design is its tendency to break in the middle 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 is therefore recommended to widen the wing around the middle, to give it extra strength.

To get the desired effect and to make the boomerang come back it is important to remember the following points when throwing a boomerang.

Hold the boomerang by either wing tip in a tight grip with the curved side facing towards you. This gives the boomerang lift, so if you throw it the other way round, it will crash into the ground. The tight grip makes the boomerang snap out of your hand as you throw it, giving it all important spin. Hold the boomerang vertical or slightly off vertical. As a boomerang thrown horizontally will fly rapidly skyward, and then crash down to the ground on the return path.

The Omega boomerang requires more tilt away from the vertical than the V-shaped (about 15 degrees off vertical). It is easy to think you are throwing vertically when in fact your hand twists at the last moment, resulting in a near horizontal launch. Try thinking about where the boomerang is as you throw it, and keep your throwing arm against your head. Try to end the throw with your arm down beside your leg, so it has to go straight to get there.

Aim the boomerang about 15 degrees above ground level. This can easily be imagined by aiming just above treetops about 200 metres away. Throw your boomerang at about 50 degrees to the right of the wind (or to the left if you are left handed). If it is thrown too much to the right, the boomerang will land early in its flight in front, and to the right of you. Too much to the left, and the boomerang will fly past you landing behind and to the left of you.

Throw more vertically in windy conditions, and more off vertical in calm conditions. Use less power in your throw but keep up the spin rate, otherwise the boomerang will lose stability. The reduced power is used up as the boomerang flies into the wind, so it gets blown back to your hands, rather than ending up behind you.