Lightweight hollow drive shaft assembly

Claim 1

IN AN AXIAL FLOW MACHINE, A HOLLOW DRIVE SHAFT ASSEMBLY OPERABLE IN AN AREA UNDER HIGH AMBIENT PRESSURE ON THE OUTSIDE, AND A LOWER PRESSURE ON THE INSIDE OF SAID DRIVE SHAFT ASSEMBLY COMPRISING: A SOLID WALL HOLLOW OUTER STRUCTURE JOINABLE AT EACH END TO A ROTATING ELEMENT OF SAID MACHINE FOR TRANSMITTING TORQUE AT HIGH SPEED FROM ONE OF THE SAID ROTATING ELEMENTS TO THE OTHER ROTATING ELEMENT; SAID A HOLLOW INNER STRUCTURE HAVING A PLURALITY OF FLUTES WITH SIDEWALLS AT AN ANGLE TO THE GENERAL OUTER WALL SURFACE OF SAID INNER STRUCTURE, THE OUTER WALL SURFACE BETWEEN THE FLUTES BEING IN PROXIMITY WITH THE INNER WALL SURFACE OF SAID OUTER STRUCTURE AND SUPPORTING, THROUGH THE EFFECT OF CENTRIFUGAL FORCE DURING HIGH SPEED ROTATION, THE SAID OUTER STRUCTURE AGAINST THE INWARDLY DEFLECTING INFLUENCE OF THE EXTERNAL AMBIENT PRESSURE.