A physics-based dynamic model of a twin-spool turboshaft engine that drives a variable pitch propeller is developed. The primary purpose for the development of this model is for researchers to use it to develop new engine control algorithms and study/predict off-design transient responses of gas turbine propulsion systems. In this model, the dynamics of the engine are defined to be the two spool speeds, and the control inputs are defined to be the fuel flow rate and the propeller pitch angle. Mockups of the turboshaft engineandthevariablepitchpropelleraredevelopedusingCADsoftware,and based on the mockups, a test stand for gas turbine engine static tests is developed. Experimental results are used to verify the dynamic model of the JetCat SPT5 turboshaft engine with a variable pitch propeller mounted on it. Based on experimental data, realistic performance maps of the engine components, including the high-pressure compressor, highand low-pressure turbines, and variable pitch propeller are constructed and integrated in the model. The developed engine model is then validated with experimental results for various propeller pitch angles. The engine numerical model is implemented using MATLAB, and open-loop simulation results for large throttle commands are presented.