A variable rotor blade mechanism for use in a gas turbine engine, the mechanism comprising: a blade rotor for rotating about an axial engine centerline during operation of the gas turbine engine; a blade (12; 45B) extending radially from the blade rotor and configured for rotation about a radial axis; a harmonic drive system (76; 136) mounted to the blade rotor and connected to the blade (12; 45B) to rotate the blade about the radial axis the harmonic drive system (76; 136) comprising: a flexible gear (88; 146) mounted to the blade rotor such that it rotates about the centerline with the blade rotor; and a rigid gear (86; 144) engaged with the flexible gear (88; 146); a stepper motor (80; 140) for driving the harmonic drive (76; 136) with relative rotational input with respect to the rotation of the blade rotor, a bracket (84; 40A) disposed about the engine centerline for supporting the stepper motor (80; 140) stationary with respect to the rotation of blade rotor such that the relative rotational input to the stepper motor (80; 140) is generated; said stepper motor (80; 140) comprising: a stator (94; 148) mounted to the bracket (84; 40A) such that it circumscribes the centerline; and a drive rotor (96; 150) configured for rotation about the stator (94; 148) wherein the drive rotor (96; 150) acts as a drive input to the flexible gear (88; 146) to cause relative rotation of the rigid gear (86; 144) about the centerline with respect to the blade rotor such that the rigid gear (86; 144) rotates said blade (12; 45B) about said radial axis; characterised in that: said flexible gear circumscribes said drive rotor (96; 150) such that said drive rotor (96; 150) is within said flexible gear and said drive rotor (96; 150) has an elliptical outer diameter such that said flexible gear takes on an elliptical shape when the drive rotor (96; 50) is inserted into said flexible gear. a blade rotor for rotating about an axial engine centerline during operation of the gas turbine engine; a blade (12; 45B) extending radially from the blade rotor and configured for rotation about a radial axis; a harmonic drive system (76; 136) mounted to the blade rotor and connected to the blade (12; 45B) to rotate the blade about the radial axis the harmonic drive system (76; 136) comprising: a flexible gear (88; 146) mounted to the blade rotor such that it rotates about the centerline with the blade rotor; and a rigid gear (86; 144) engaged with the flexible gear (88; 146); a flexible gear (88; 146) mounted to the blade rotor such that it rotates about the centerline with the blade rotor; and a rigid gear (86; 144) engaged with the flexible gear (88; 146); a stepper motor (80; 140) for driving the harmonic drive (76; 136) with relative rotational input with respect to the rotation of the blade rotor, a bracket (84; 40A) disposed about the engine centerline for supporting the stepper motor (80; 140) stationary with respect to the rotation of blade rotor such that the relative rotational input to the stepper motor (80; 140) is generated; said stepper motor (80; 140) comprising: a stator (94; 148) mounted to the bracket (84; 40A) such that it circumscribes the centerline; and a drive rotor (96; 150) configured for rotation about the stator (94; 148) wherein the drive rotor (96; 150) acts as a drive input to the flexible gear (88; 146) to cause relative rotation of the rigid gear (86; 144) about the centerline with respect to the blade rotor such that the rigid gear (86; 144) rotates said blade (12; 45B) about said radial axis; characterised in that: said flexible gear circumscribes said drive rotor (96; 150) such that said drive rotor (96; 150) is within said flexible gear and said drive rotor (96; 150) has an elliptical outer diameter such that said flexible gear takes on an elliptical shape when the drive rotor (96; 50) is inserted into said flexible gear. a stator (94; 148) mounted to the bracket (84; 40A) such that it circumscribes the centerline; and a drive rotor (96; 150) configured for rotation about the stator (94; 148) wherein the drive rotor (96; 150) acts as a drive input to the flexible gear (88; 146) to cause relative rotation of the rigid gear (86; 144) about the centerline with respect to the blade rotor such that the rigid gear (86; 144) rotates said blade (12; 45B) about said radial axis; characterised in that: said flexible gear circumscribes said drive rotor (96; 150) such that said drive rotor (96; 150) is within said flexible gear and said drive rotor (96; 150) has an elliptical outer diameter such that said flexible gear takes on an elliptical shape when the drive rotor (96; 50) is inserted into said flexible gear. said flexible gear circumscribes said drive rotor (96; 150) such that said drive rotor (96; 150) is within said flexible gear and said drive rotor (96; 150) has an elliptical outer diameter such that said flexible gear takes on an elliptical shape when the drive rotor (96; 50) is inserted into said flexible gear.