A coupling for connecting a propeller to a motor, comprising: a propeller coupling portion including; a propeller hub for supporting a propeller blade (111, 112); an inner propeller hub bore defining an axial keyway (120, 121, 122) defined in said propeller hub; a motor coupling portion (102, 202) including: a rotatable shaft connectable for rotation with the motor, the rotatable shaft having an internal shaft bore; a radial aperture extending through said rotatable shaft, from the internal shaft bore to the outer shaft surface; a radial key (150, 151, 152) slidably located in said radial aperture; an actuator slidably mounted within said internal shaft bore of said rotatable shaft; said rotatable shaft engaging within said inner propeller hub bore; wherein by depressing said actuator said radial key (150, 151, 152) can retract relative to an outer surface of said rotatable shaft for permitting said propeller hub bore to be introduced onto said rotatable shaft and permitting rotation of said propeller hub relative to said rotatable shaft to align said radial key (150, 151, 152) with said axial keyway (120, 121, 122); the motor coupling portion (102, 202) further including a spring which, upon release of the actuator, biases said actuator into a non-depressed position for extending said radial key (150, 151, 152) to engage with said axial keyway (120, 121, 122) of said propeller hub bore to couple the propeller to the motor and prevent rotation of said propeller hub relative to said rotatable shaft; and wherein by depressing said actuator said radial key (150, 151, 152) can retract from said axial keyway (120, 121, 122) permitting removal of said propeller hub from said rotatable shaft. a propeller coupling portion including; a propeller hub for supporting a propeller blade (111, 112); an inner propeller hub bore defining an axial keyway (120, 121, 122) defined in said propeller hub; a motor coupling portion (102, 202) including: a rotatable shaft connectable for rotation with the motor, the rotatable shaft having an internal shaft bore; a radial aperture extending through said rotatable shaft, from the internal shaft bore to the outer shaft surface; a radial key (150, 151, 152) slidably located in said radial aperture; an actuator slidably mounted within said internal shaft bore of said rotatable shaft; said rotatable shaft engaging within said inner propeller hub bore; wherein by depressing said actuator said radial key (150, 151, 152) can retract relative to an outer surface of said rotatable shaft for permitting said propeller hub bore to be introduced onto said rotatable shaft and permitting rotation of said propeller hub relative to said rotatable shaft to align said radial key (150, 151, 152) with said axial keyway (120, 121, 122); the motor coupling portion (102, 202) further including a spring which, upon release of the actuator, biases said actuator into a non-depressed position for extending said radial key (150, 151, 152) to engage with said axial keyway (120, 121, 122) of said propeller hub bore to couple the propeller to the motor and prevent rotation of said propeller hub relative to said rotatable shaft; and wherein by depressing said actuator said radial key (150, 151, 152) can retract from said axial keyway (120, 121, 122) permitting removal of said propeller hub from said rotatable shaft. a rotatable shaft connectable for rotation with the motor, the rotatable shaft having an internal shaft bore; a radial aperture extending through said rotatable shaft, from the internal shaft bore to the outer shaft surface; a radial key (150, 151, 152) slidably located in said radial aperture; an actuator slidably mounted within said internal shaft bore of said rotatable shaft; said rotatable shaft engaging within said inner propeller hub bore; wherein by depressing said actuator said radial key (150, 151, 152) can retract relative to an outer surface of said rotatable shaft for permitting said propeller hub bore to be introduced onto said rotatable shaft and permitting rotation of said propeller hub relative to said rotatable shaft to align said radial key (150, 151, 152) with said axial keyway (120, 121, 122); the motor coupling portion (102, 202) further including a spring which, upon release of the actuator, biases said actuator into a non-depressed position for extending said radial key (150, 151, 152) to engage with said axial keyway (120, 121, 122) of said propeller hub bore to couple the propeller to the motor and prevent rotation of said propeller hub relative to said rotatable shaft; and wherein by depressing said actuator said radial key (150, 151, 152) can retract from said axial keyway (120, 121, 122) permitting removal of said propeller hub from said rotatable shaft.