1. A VARIABLE DIAMETER PROPELLER ASSEMBLY COMPRISING AT LEAST ONE BLADE HAVING AN OUTBOARD AND AN INBOARD SECTION, SAID OUTBOARD SECTION RETRACTABLE WITH RESPECT TO SAID INBOARD SECTION, MEANS FOR RETRACTING SAID OUTBOARD SECTION, AND DRIVING MEANS FOR ROTATING SAID BLADE AND IMPARTING TORQUE TO SAID RETRACTING MEANS, SAID RETRACTING MEANS ACTUATED WHEN SAID TORQUE IMPARTED THERETO EXERTS A FORCE ON THE OUTBOARD SECTION OF SAID ROTATING BLADE THAT EXCEEDS THE CENTRIFUGAL FORCE EXERTED ON THE OUTBOARD SECTION OF SAID ROTATING BLADE.