Rapid Aircraft-Level Evaluation of Revolutionary Propulsion Concepts
Creators: name: Seitz, Arne
Publisher: name: Zenodo
Year: 2023

description: Advanced propulsion system technologies remain a key factor in ensuring the aircraft energy and emission reductions needed in order to achieve aviation’s long-term climate and sustainability targets. The required step improvements in system efficiency and emission characteristics demands for technological options that go clearly beyond the classic technological evolution. As a result, alternative types of energy have entered the serious discussion of potential systemic solutions for aviation propulsion and power, alongside with revolutionary technological options, such as advanced fuel cells or radical heat engines. Especially, the prospect of green hydrogen as a possible energy source for aircraft propulsion and power has recently been spurring new ideas for revolutionary power plant systems. A quick incubation and rapid initial technical assessment of such new ideas is necessary in order to identify suitable candidate solutions for subsequent speedy technology maturation targeted to meet the mid-century market demands in commercial air transport.

In order to serve the need for a swift and integrated evaluation of revolutionary propulsion system technology concepts, Bauhaus Luftfahrt's existing in-house Aircraft Design Environment (BLADE) has been complemented by a set of simplified methods for the pre-conceptual scaling of advanced aircraft. With a reduced set of design parameters and extremely rapid response times, this “Level 0” model dubbed SAS (Simplified Aircraft Scaling) enables a particularly quick gain of basic knowledge on integrated system efficiency and emissions behaviour. As well, it provides a solution for the immanent starting value problem associated with more sophisticated aircraft conceptual and pre-design tooling.

In this contribution, the methodological foundation of SAS is introduced and its capabilities are demonstrated based on insightful case studies. Therefore, the applied top-down approach to resolving aircraft vehicular efficiency is discussed, including a unified formulation of propulsion system efficiency, aircraft aerodynamic efficiency and aircraft mass breakdown mapping . A library of aircraft and propulsion system design and performance heuristics  reflecting key characteristics of state-of-the-art subsonic fixed wing air transport vehicles is introduced. The adopted aircraft and propulsion system design scaling procedure is explained as well as the approach to mapping the integration of advanced technologies. Results for representative aircraft-level validation cases are provided. Beyond the baseline setup, a number of selected methodological extensions are highlighted including capabilities for the evaluation of fuselage Boundary Layer Ingesting (BLI) propulsion integration, liquid hydrogen fuel options as well as fuel cell – gas turbine hybrid propulsion systems. To round of, initial assessment results for three hydrogen fueled airliners with revolutionary propulsion system architectures are presented that span the regional, short-range and long-range market segments.