In this paper, different iterative methods, so-called architectures, within the multidisciplinary analysis in conceptual aircraft design of the UNICADO software are elaborated, applied and analyzed. Possible execution sequences in the sequential method (Gauss-Seidel architecture) are derived via a graph-based algorithm in combination with expert knowledge. Sensitivities of the design disciplines are analyzed and a permitted residual for stable convergence characteristic for the aircraft design with UNICADO is derived. Prerequisites for the application of a parallel iterative method, the Jacobi architecture are conducted. Runtime and convergence characteristics of the Gauss-Seidel architecture and the Jacobi architecture are evaluated. A damping method is applied to the Jacobi architecture to enhance the convergence characteristics. The Gauss-Seidel and Jacobi architectures are used to design two different aircraft, the CSR and the CSMR, with an iteration accuracy of 2.5e–3. For these use cases studied, the Gauss-Seidel architecture converges more stably and faster than the Jacobi architecture and is, therefore, the more favorable. The aircraft design with the implemented Jacobi architecture oscillates and does not converge. Only with an implemented damping method, convergence is achieved. If the iteration time of the design loop increases, e.g., when using higher fidelity methods for aircraft design, the choice of architecture must be re-evaluated.

In this paper, the UNICADO 2.0 software is used to simulate and evaluate measures regarding the reduction of energy consumption and climate impact of long-range aircraft. For this purpose, an Airbus A350-900-like reference aircraft powered by a Trent XWB-84-like aero engine is generated. The measures investigated are SAF, liquid hydrogen and a reduction in cruise speed. The design of a liquid hydrogen aircraft with cryogenic tanks hereby discloses significant challenges regarding landing gear integration, tail strike and competitive transport work. The combined implemented measures of liquid hydrogen and a reduced cruise speed lead to a maximum reduction, compared to the reference aircraft, in the climate impact of 82% in average temperature potential, 80% in absolute global warming potential and 76% in absolute global temperature potential; however, leading to an increase in fuel consumption of 13.6% due to the lower cruise Mach number. This and the necessary change to an economy-class-only layout over two passenger decks for the liquid hydrogen configuration show the at times inverse relation of climate impact reduction measures and economic feasibility. Furthermore, the scope of interest is shifted over the system boundaries of the aircraft. Thus, including hydrogen production in the environmental evaluation. Assuming a production in Germany in the year 2022, an increase in the $$\textrm{CO}_2$$ equivalent of 156% compared to the reference aircraft is obtained. However, when assuming energy production solely from wind turbines a reduction of 92% is possible.

This paper presents an integrated assessment of liquid hydrogen as an aviation energy carrier, covering fuel production, aircraft performance, and fleet-level climate impacts. The results, based on the H2Avia research project, indicate substantial potential for reducing life-cycle global warming impacts compared to conventional kerosene. The analyses conducted for the interdisciplinary assessment are presented. The analysis shows that the use of liquid hydrogen eliminates CO₂ emissions during fuel burn, resulting in a significant reduction in global warming potential compared to conventional kerosene, despite remaining upstream emissions from production and transport. The aircraft application cases and the applied technologies assessment scenario are described. The modeled technologies essential for the hydrogen aircraft are discussed, and exemplary values are given. Integrated overall aircraft performance results are given and discussed. At the aircraft level, hydrogen-based aircraft require an 8–18% increase in design mission block energy compared to a 2040 kerosene baseline yet still achieve a reduction in effective global warming potential of 55–86% comparing a representative pair route between Europe and North America (6730 km). An overview of the fleet modeling approach and the applied scenarios is given. For a scenario with energy cost and climate impact as equally weighted minimization goals, the global fleet analysis yields a global warming potential reduction of 60% compared to the non-liquid hydrogen baseline scenario. Overall, the results suggest that liquid hydrogen-powered aircraft can deliver significant mission- and fleet-level reductions in global warming potential and thus represent a promising pathway for achieving long-term aviation climate targets.

Aircraft conceptual design has been used for years to develop new aircraft configurations or to evaluate new technologies in existing configurations. For this reason, competence-driven aircraft preliminary design environments have been developed worldwide, especially in universities, which are more or less at the same level. Since synergy potentials regarding the core competences of the universities remain unused, the association of the universities involved in the UNICADO research project is unique. The aim of the project is to bundle this synergy potential in the form of a common developed and used aircraft conceptual design environment. This paper describes this design environment developed based on RCE and the associated boundary conditions regarding the design of CS-25 compliant aircraft. UNICADO is implemented as a modular architecture for an easy extensibility and exchangeability of modules and disciplines. For an exact statement about the quality of the results, the developed platform is validated by means of a comparison with the existing MICADO by RWTH Aachen University. The main design mode as well as the implemented calibration modes will be validated and critically evaluated using the CeRAS CSR-01 reference aircraft. Subsequently, the results of the design of a CeRAS short- and medium-range aircraft and a CeRAS long-range configuration are presented and compared with selected reference aircraft. The comparison of the CSMR-01 and CLR designed with UNICADO to the reference aircraft on the market shows that the design environment developed for the early design phase delivers very good results. The resulting percentage deviations between the design and the reference aircraft are less than one percent for all convergence variables considered. This shows that the cooperative approach to bundle core competencies and exploit synergy potentials is effective and should be intensified in further project phases. UNICADO provides a solid foundation for the development of modern, climate-friendly aircraft. Extending the software with more advanced methods will improve the ability to model disruptive configurations and alternative propulsion concepts. Being designed as open-source software, anyone can use, understand and improve the software and contribute their own ideas for future aircraft configurations.