DC servo motor is often used as an actuator for achieving deflection (rotation) of aircraft control surfaces such as elevator, aileron, rudder, etc. In open loop, a DC motor can be modeled as a first order system as = where is angular speed of the motor in rad/s and is voltage input to the motor in volts, is the mass moment of inertia of the rotor, is damping torque constant on the rotor due to back emf, and is motor torque constant