Rotor blade and pressure regulating arrangement

A rotor blade for a reaction jet helicopter, the rotor blade comprising a cavity and one or more nozzles for the expulsion of compressed air from the rotor blade cavity thereby resulting in rotation of the rotor blade, the rotor blade further comprises a pressure regulating arrangement, the pressure regulating arrangement being operable to release compressed air from the rotor blade cavity, wherein the rotor blade further comprises one or more outlet apertures, wherein the pressure regulating arrangement comprises one or more fluid pathways, wherein the one or more fluid pathway comprises a plenum chamber, each plenum chamber equalizing an air pressure supply to the one or more outlet apertures along an upper surface of the rotor blade, wherein the pressure regulating arrangement comprises one or more valves operable to release air from the rotor blade cavity, wherein compressed air travelling through the cavity does not have to pass through the one or more valves to reach the one or more nozzles.