Research on how to measure/estimate reaction torque
In addition to thrust force, a spinning propeller will also introduce reaction torque onto system. According to paper [1], there is a strong linear relationship between a propeller’s reaction torque and thrust force. Once this relationship is found, we can add the reaction torque onto the simulink simulation. To measure reaction torque, a torque sensor is needed.
[1] Mark W. Mueller and Raffaello D’Andrea "Stability and control of a quadrocopter despite the complete loss of one, two, or three propellers"