A boomerang is basically a single-winged aircraft propelled through the air by hand. Boomerangs have two ‘wings’ joined in a V-shape. Both wings have an airfoil-shaped cross-section just like an aircraft wing. An airfoil is ﬂ at on one side but curved on the other with one edge thicker than the other – this helps the boomerang stay in the air due to lift.
Lift is generated as the air ﬂowing up over the curved side of the wing has further to travel than the air ﬂowing past the ﬂat side. The air moving over the curved surface must therefore travel quicker in order to reach the other edge of the wing.
Because the two sides of a boomerang have different air speeds ﬂowing over them, as it spins the aerodynamic forces acting upon it are uneven. This causes the section of the boomerang moving in the same direction as the direction of forward motion to move faster through the air than the section moving in the opposite direction. These uneven forces make the boomerang start to turn in and follow a circular route, eventually heading back to the thrower.