Aircraft propulsive power unit

An aircraft propulsive power unit comprising

• an efflux duct in which gaseous fluid is conducted in a predetermined first flow path for discharge from an exit end of the duct in the production of forward thrust, and a thrust reversing arrangement which in an operative disposition redirects gaseous fluid flowing in the first flow path into a second flow path to produce reverse thrust, wherein
• the reversing arrangement has a flow redirecting structure which is displaceable between an operative disposition and an inoperative disposition and which comprises a flow redirecting zone which intercepts fluid flow in the first flow path and redirects it into the second flow path when the redirecting structure moves to the operative disposition,
• the propulsive power unit is a turbofan power unit including a fan duct,
• the efflux duct is the fan duct of the turbofan unit,
• the turbofan unit includes a nacelle having a cowl structure to support ambient flow thereover including a forward cowl portion,
• the flow redirecting structure includes a displaceable cowl portion which in the inoperative disposition of the redirecting structure forms part of the cowl structure to support ambient flow and in the operative disposition of the redirecting structure occupies a position in which it presents a cowl opening in the cowl structure to allow flow in the second flow path,
• the redirecting structure in the inoperative disposition takes up a forward disposition with a leading edge of the displaceable cowl portion abutting a trailing edge of the forward cowl portion and in the operative disposition takes up a rearward disposition with the leading edge of the displaceable cowl portion spaced from the trailing edge of the forward cowl portion to provide the cowl opening.
• a cascade assembly extends rearwardly across the cowl opening from a forward end from which it is cantilevered:
• wherein
• (i) the cascade assembly terminates at a rearward end at a position in which it is forwardly spaced from the leading edge of the displaceable cowl portion when the redirecting structure is in the operative disposition thereby to provide a flow control slot between the rearward end of the cascade assembly and the leading edge of the displaceable cowl portion,
• (ii) the second flow path comprises a primary reverse thrust flow through the cascade assembly and a secondary reverse thrust flow through the control slot and
• (iii) a baffle is mounted on the leading edge of the displaceable cowl portion defining the trailing edge of the control slot when the redirecting structure is in the operative disposition and overlaps with the trailing edge of the forward cowl portion when the redirecting structure is in the inoperative disposition.