Why do Boomerangs Come Back?
Boomerangs work on the same principles of aerodynamics as any other flying object; the key to how a boomerang works is the airfoil.
An airfoil is flat on one side but curved on the other with one edge thicker than the other – this subjects the boomerang to lift, keeping it in the air. The lift is generated because the air flowing up over the curve of the wing has further to travel than the air flowing past the flat side. The air moving over the curve travels faster in order to reach the other side of the wing, creating lift.
A boomerang has two airfoils, each facing in a different direction. This makes the aerodyamic forces acting on a thrown boomerang uneven. The section of the boomerang moving in the same direction as the direction of forward motion moves faster than the section moving in the opposite direction. Just like tank tracks moving at different speeds, this causes the boomerang to turn in the air and return to the thrower.
Fast Fact: Most original boomerangs don’t come back, and are not intended to do so! The returning variety are thought to have been made to scare birds into hunters nets.