Fielding High Energy Laser (HEL) weapon systems presents technological challenges as well as employment and financial challenges. The risk associated with the challenges mandates the development process include computer simulation models capable of predicting weapon system performance from the engineering level to assessing the military worth of employing HEL systems in combat scenarios. This research effort focuses on developing laser performance data at a higher fidelity engagement model and integrating the performance data into a mission level model. The propagation of the laser from the transmitting aperture to the target is modeled at the engagement level through the employment of the High Energy Laser End-to-End Operational Simulation (HELEEOS), developed by the AFIT Center for Directed Energy (CDE).