PC Krause and Associates is partnering with Purdue University, EleQuant, and GridQuant to create a hybrid modeling capability. The combination of PCKA's extensive dynamic modeling experience, Purdue's work in electromechanical systems analysis, and GridQuant and Elequant's development of the HELM algorithm uniquely positions the team to create this technology. HELM is a novel algorithm that solves the powerflow equations of electric power systems using a direct, constructive procedure. It was originally derived for terrestrial power grids and is now being applied to dc spacecraft power systems. The Phase I effort will focus on three technical objectives. The first is to provide a formal definition of the mathematical framework for the hybrid modeling capability. The second objective is to define a software architecture for its implementation. Lastly, the third objective is to demonstrate the capability on an aircraft electrical propulsion system. The test system is anticipated to be a variable-voltage/variable-frequency ac electrical propulsion system that PCKA is currently investigating with NASA as part of a Convergent Aeronautics Solutions (CAS) effort. Another alternative is the Hybrid Gas Electric Propulsion (HGEP) Project's NASA Electric Aircraft Testbed (NEAT) system, which PCKA is also currently modeling. Some potential applications for this modeling technique include some of these applications include 1) efficient contingency analysis, 2) model-based control, 3) system identification and monitoring, and 4) analysis of pulsed loads.