Conceptual Design of the Hybrid-Electric Subsonic Single Aft Engine (SUSAN) Electrofan Transport Aircraft
Timothy Chau, Jared C. Duensing
Abstract
This paper presents an update to the conceptual design of the NASA Subsonic Single Aft Engine (SUSAN) Electrofan transport aircraft---a 180 passenger, Mach 0.785 hybrid-electric regional jet with an economy range of 750 nmi and a design range of 2,500 nmi. The concept employs a series/parallel partial hybrid-electric powertrain driven by a fuel-burning aft fuselage propulsor connected to Megawatt-class power generators, which support wing-mounted electric propulsors. The aft fuselage turbofan leverages boundary layer ingestion (BLI) and is designed to deliver 35% of the total aircraft thrust, while the wing propulsors assume underwing distributed electric propulsion (DEP) configurations and are responsible for the remaining 65% aircraft thrust. Investigated in this work is the system level sizing and analysis of the SUSAN Electrofan when accounting for system level trades related to its electrified aircraft propulsion (EAP) systems. Updated disciplinary models and key performance parameters are incorporated, including those related to the power, battery, and thermal systems. A unified propulsion system model is also included, which accounts for the high effective bypass ratio made possible by DEP, and turbofan BLI effects to first order. Conceptual multidisciplinary design analysis and optimization (MDAO) is used to determine the EAP system technology levels required to close the SUSAN Electrofan concept based on the current set of design requirements and assumptions. Comparisons of fuel burn performance to a reference aircraft based on the Boeing 737 MAX 8 are presented, as well as comparisons to a variant resized for the same range capabilities as the SUSAN Electrofan.