The first is to use an enclosured ducted fan rather than openly exposed rotor blades. This design is referred to as a "fantail" or "Fenestron", a trademark of Eurocopter (now Airbus Helicopters) for its Dauphin-series utility helicopters. The enclosure around the fan reduces tip vortex losses, shields the blades from foreign object damage, protects ground crews from potential hazard of an openly spinning rotor, and produces a much quieter and less turbulent noise profile than a conventional tail rotor. The ducted fan uses more numerous shorter blades, but otherwise works in very similar thrust principles to a conventional tail rotor.