An electromechanical system comprising: a driving component having a drive rotor rotatable about an axis; and a driven component, wherein the driven component is a turbine engine comprising a turbine rotor rotatable about the axis, the driving component is an electrical starter motor for the turbine engine, and the drive rotor of the starter motor is a starter rotor, wherein the electromechanical system further comprises: a turbine shaft comprising a rotationally flexible shaft portion disposed in operable communication with the starter rotor and the turbine rotor and operably connected thereto such that rotation of the starter rotor about the axis drives rotation of the turbine rotor about the axis, wherein a difference in the amount of rotation of the starter rotor and the turbine rotor is indicative of a load on the turbine engine; an electrical property sensor in operable communication with the starter motor to measure an electrical property of the starter motor, to determine an angular position of the starter rotor without using a rotor position sensor, wherein the angular position of the starter rotor is determined mathematically using an algorithm which uses a known profile of the electrical property as a function of angular position of the starter rotor, such that the angular position of the starter rotor can be determined by measuring the electrical property of the starter motor and comparing the measured value to the known profile, wherein the electrical property is voltage and/or current; and a position sensor in operable communication with the turbine rotor to determine an angular position thereof, wherein the system is configured to calculate a magnitude of a load on the turbine engine based on a calculation of a difference in the determined angular position of the starter rotor and the determined angular position of the turbine rotor and a known torsional rigidity of the shaft portion. a driving component having a drive rotor rotatable about an axis; and a driven component, wherein the driven component is a turbine engine comprising a turbine rotor rotatable about the axis, the driving component is an electrical starter motor for the turbine engine, and the drive rotor of the starter motor is a starter rotor, wherein the electromechanical system further comprises: a turbine shaft comprising a rotationally flexible shaft portion disposed in operable communication with the starter rotor and the turbine rotor and operably connected thereto such that rotation of the starter rotor about the axis drives rotation of the turbine rotor about the axis, wherein a difference in the amount of rotation of the starter rotor and the turbine rotor is indicative of a load on the turbine engine; an electrical property sensor in operable communication with the starter motor to measure an electrical property of the starter motor, to determine an angular position of the starter rotor without using a rotor position sensor, wherein the angular position of the starter rotor is determined mathematically using an algorithm which uses a known profile of the electrical property as a function of angular position of the starter rotor, such that the angular position of the starter rotor can be determined by measuring the electrical property of the starter motor and comparing the measured value to the known profile, wherein the electrical property is voltage and/or current; and a position sensor in operable communication with the turbine rotor to determine an angular position thereof, wherein the system is configured to calculate a magnitude of a load on the turbine engine based on a calculation of a difference in the determined angular position of the starter rotor and the determined angular position of the turbine rotor and a known torsional rigidity of the shaft portion. a turbine shaft comprising a rotationally flexible shaft portion disposed in operable communication with the starter rotor and the turbine rotor and operably connected thereto such that rotation of the starter rotor about the axis drives rotation of the turbine rotor about the axis, wherein a difference in the amount of rotation of the starter rotor and the turbine rotor is indicative of a load on the turbine engine; an electrical property sensor in operable communication with the starter motor to measure an electrical property of the starter motor, to determine an angular position of the starter rotor without using a rotor position sensor, wherein the angular position of the starter rotor is determined mathematically using an algorithm which uses a known profile of the electrical property as a function of angular position of the starter rotor, such that the angular position of the starter rotor can be determined by measuring the electrical property of the starter motor and comparing the measured value to the known profile, wherein the electrical property is voltage and/or current; and a position sensor in operable communication with the turbine rotor to determine an angular position thereof, wherein the system is configured to calculate a magnitude of a load on the turbine engine based on a calculation of a difference in the determined angular position of the starter rotor and the determined angular position of the turbine rotor and a known torsional rigidity of the shaft portion.