The first Frisbees came free with the purchase of the “invisible string” that they appeared to be attached to when they flew. Their magical flight paths have fascinated many since. They go round corners and twist and turn when thrown upside down. Controlling the route taken by the flying disk is of particular interest to aficionados of “ultimate”, a high-speed sport in which passing to team-mates doesn’t have to involve straight lines. Dr Trevor Agus introduces the physics of Frisbee flight with demonstrations from Belfast Ultimate and Queen’s Ultimate sports clubs.