Ducted fan arrangement for aircraft

Claim 1

FAN ARRANGEMENT FOR AN AIRCRAFT, COMPRISING, IN COMBINATION, A PLURALITY OF TUBULAR WALL MEANS HAVING A COMMON AXIS AND FORMING AN INNER ANNULAR DUCT AND AN OUTER ANNULAR DUCT, SAID WALL MEANS INCLUDING STATIONARY TUBULAR WALL MEANS BETWEEN SAID OUTER AND INNER DUCTS HAVING A NARROW ANNULAR GAP; SUPPORTING MEANS SECURED TO SAID WALL MEANS AND HAVING AN INNER PART INCLUDING BEARING MEANS LOCAED IN THE REGION OF SAID AXIS; A SHAFT SUPPORTED IN SAID BEARING MEANS FOR ROATION; A TURBINE ROTOR CARRIED BY SAID SHAFT AND HAVING RADIAL TURBINE VANES LOCATED IN SAID INNER ANNULAR DUCT; FAN MEANS MOUNTED FOR ROTATION ABOUT SAID AXIS AND HAVING RADIALLY EXTENDING SPOKES LOCATED IN SAID INNER ANNULAR DUCT, A NARROW RING SECURED TO THE OUTER ENDS OF SAID SPOKES AND LOCATED IN SAID ANNULAR GAP FLUSH WITH SAID TUBULAR WALL, AND RADIAL FAN VANES PROJECTING FROM SAID RING AND LOCATED IN SAID OUTER ANNULAR DUCT, SAID SPOKES HAVING A PROFILE OFFERING LOW RESISTANCE TO THE FLOW OF GASES THROUGH SAID INNER ANNULAR DUCT AND CAUSING NO PROPULSION OF GASES IN THE SAME; AND REDUCTION TRANSMISSION MEANS CONNECTING SAID SHAFT WITH SAID FAN MEANS FOR DRIVING THE LATTER AT A SELECTED ROTARY SPEED LOWER THAN THE ROTARY SPEED OF SAID TURBINE ROTOR SO THAT THE CENTRIFUGAL FORCE ACTING ON SAID FAN VANES DOES NOT EXCEED A PREDETERMINED LIMIT.