Flying disc
Gyroscopic precession causes the disc to rotate toward horizontal through its flight path. Unlike a right-side up throw, however, an upside-down disc will not precess toward a stable flat state, and will in stead oscillate past horizontal and begin to bank in the opposite direction. This shuttlecock-like effect is known as "helixing", and is generally avoided due to the difficulty in controlling a helixing flight path. For this reason, an upside down throw is typically released with either clockwise rotation and the left edge up, or counterclockwise rotation and the right edge up. The longer the disc is expected to remain in the air, the closer to vertical it must be at release to avoid the helixing effect.