Single Gas Turbine Propulsion Options for Short-to-Medium Range Aircraft

Given the estimated 3.7% yearly increase in Revenue Passenger-Kilometers (RPK) in the aviation sector (ICAO, 2023), the reduction of aircraft emissions and the further significant improvement of in-flight energy efficiency is increasingly becoming a major industry challenge. With step change efficiency improvements based on conventional design paradigms becoming increasingly difficult to realize, novel propulsion system concepts may be a key enabler to achieve the global goal of climate neutral aviation. In this context, the present paper introduces the concept of Single Gas Turbine (SGT) propulsion system configurations for Short-to-Medium Range (SMR) aircraft. After a clear definition of the terminology around SGT propulsion systems, the expected benefits, key challenges and certification implications of such novel powertrain approaches are discussed. The selected application of a SMR hydrogen-fueled aircraft is motivated and eligible SGT system options are characterized. A special focus is given to Fuel Cell-Gas Turbine- Hybrid (FC-GT-Hybrid) configurations, highlighting the synergies between the gas turbine and the fuel cell in the context of a SGT propulsion system. All collected configuration options are organized in an overarching concept cloud and categorized by their specific traits and system complexities. Based on technical feasibility, certification, failure resistance and lessons learned from battery-electric propulsion concepts, the introduced concept cloud is condensed down to a core group of most promising SGT configurations. To round-off, the methodology for quantitative performance evaluation of these SGT configurations at the propulsion system and aircraft integrated levels are characterized and immediate next steps are detailed.