(Phys.org)—When it comes to flying projectiles,the badminton shuttlecock or "birdie" is unusual in that it flips on impact with a racket so that it always flies cork-first. This flipping motion arises from the fact that, unlike nearly all other sports projectiles, or the shuttlecock has a conical shape and,because the cork is much denser than the feathers, a non-homogeneous mass.
Source: phys.org