# How does a boomerang fly?

## Why is the boomerang returning?

A boomerang flies because its “arms” are like the wings of an airplane. This creates a lift. Its circular orbit comes from its rotation, which causes different levels of lift on its two wing tips. Together with stabilizing gyroscopic forces, a curve is created.

1) Static buoyancy. Everything is at rest here. Something is puffing up. Something is filled with hot air. Something is taking off. Calmly. It is exactly the principle by which the ship floats. It has a bulbous, voluminous shape, the upper part is in an area of ​​lower water pressure than the lower part, which is in an area of ​​higher water pressure. So at the bottom it presses more on the ship and it is carried upwards. With a force called static buoyancy. It goes up when this buoyancy is greater than the weight - the weight. This is also the case with hot air balloons. Here the whole thing takes place in the air, it takes a very big difference between above and below so that the bottom presses more on the balloon. The hot air balloon has a second trick - it is easy to use, it fills itself with hot air that is more extensive and therefore has less weight per cubic meter. This means that the buoyancy does not need to be too great because the weight of the balloon is also kept small.

2) Dynamic lift. You can move up here, even if you don't have a lot of volume. But you need speed for that. Then you turn your wings a little - they are pushed upwards by the pushing air particles. Buoyancy again - which must be greater than the weight of the thing in flight. The bumblebee, which is said to be unable to fly, it just doesn't know, uses eddies to help increase lift. Well-built aircraft also use the profile of the wings, which create additional suction because they are more rounded at the top than at the bottom.

A boomerang now has precisely such wings "mounted in a circle".

The rotation of the boomerang always gives the wing moving in the direction of flight a higher lift. As a result of this asymmetrical buoyancy effect, the boomerang's axis of rotation inclines continuously. This leads to a change in the flight direction, which ideally creates a circular flight path to the starting point of the throw.

Why the boomerang returns in detail can only be answered mathematically - and that is quite complicated - in a meaningful way.

In any case, only the usual laws of physics play a role, no tricks.

The following points, which distinguish a boomerang from a normal piece of wood, have an important influence:

Booomeransgs are flat and built in such a way that they rotate stably and do not go into a tailspin. Therefore, the same laws apply here as with the roundabout - and are actually responsible for a large part of the return properties. The boomerang's arms, no matter how many, are designed like wings and generate lift, which explains why it flies in the first place.

The buoyancy effect of the arms is different. The arm that is currently turning in the direction of flight has a different lift than the one that is turning back in relation to it. The blades of helicopters also have different levels of lift, depending on which are moving in the direction of flight and which are against them. However, this is undesirable with helicopters. A cyclical blade adjustment corrects the effect in which the rotor blades moving in the direction of travel have a lower angle of attack than the retreating rotor blades.

By the way: not every boomerang returns: The traditional hunting boomerang does not return to the thrower: its advantage is precisely that it flies further, more straightforwardly and thus more accurately than a straight stick.

(Author: Lothar Bodingbauer, with the help of a no longer known student, Photo: Jonn Leffmann, Wikimedia)