A reduced order dynamic aircraft model has been created for the purpose of enabling constructive simulation studies involving integrated thermal management subsystems. Such studies are motivated by the increasing impact of on-board power and thermal subsystems to the overall performance and mission effectiveness of modern aircraft. Previous higher-order models that have been used for this purpose have the drawbacks of much higher development time, along with much higher execution times in the simulation studies. The new formulation allows for climbs, accelerations and turns without incurring computationally expensive stability considerations; a dynamic inversion control law provides tracking of user-specified mission data. To assess the trade-off of improved run-time performance against model capability, the reduced order formulation is compared to a traditional six degree-of-freedom model of the same air vehicle. Thrust command comparisons against the higher fidelity model are shown to be excellent when the aerodynamics is properly conditioned, and a methodology for transforming existing higher-order models into the new formulation is suggested. It is believed that the present air vehicle plant model and its associated controller will prove valuable in executing constructive simulation studies, including those that investigate the impact of thermal management subsystems on the overall vehicle performance and capability.