Alejandra Uranga

Battery models used in electrified aircraft conceptual design must properly capture the quantities that drive aircraft sizing: usable energy, deliverable power, voltage, current, and heat generation. This work integrates a hierarchy of lithium-ion battery models into an OpenMDAO-based aircraft design and mission optimization framework. The hierarchy includes, from lower to higher fidelity, a constant efficiency energy model, an equivalent-circuit model (ECM), and physics-based electrochemical models such as SPMe through coupling with PyBaMM. Each model is cast as a power-input component with a consistent interface: state of charge, voltage, current, and, heat load. This enables uniform coupling to propulsion, electrical-distribution, and thermal-management analyses. The models are parameterized for two commercial 21700 cells: the energy-oriented LG M50T and the power-oriented Molicel P45B. A 50-passenger all-electric aircraft case study is used to compare model fidelity and to quantify aircraft-level trade-offs between cell specific energy and allowable discharge rate. For a 300 nmi mission, the ECM and SPMe produce similar optimized aircraft weights, while the constant-efficiency model overpredicts battery and thermal-management requirements. Across shorter-range cases, climb power rather than stored energy can size the battery pack; at 100 nmi, the power-oriented cell yields a substantially lighter aircraft despite lower specific energy. The results show that battery selection for electric aircraft cannot be reduced to specific energy alone. Power limits, voltage and current behavior, heat rejection, and electrical-distribution mass must be represented in the aircraft optimization.

The increasing complexity of integrating propulsion and airframe systems in advanced and electrified aircraft requires engine models that are both accurate and robust enough to support large-scale multidisciplinary design optimization. This paper presents a formulation for modeling an engine’s thermodynamic cycle within an airframe-propulsion-trajectory optimization framework. The formulation includes a physics-based initialization method that generates analytically consistent starting conditions for all key thermodynamic state variables during on- and off-design evaluations, eliminating the need for manually tailored, well-conditioned initial guesses for the engine cycle. This is supplemented by two regulating mechanisms: an automated compressor bleed control to maintain operation within a prescribed stall margin and turbine operating constraints that prevent over-extraction and cycle closure failure. This comprehensive approach significantly improves convergence robustness and computational efficiency, allowing the thermodynamic cycle to be integrated within an aircraft multidisciplinary design optimization framework that couples the engine's design with the airframe and the aircraft operations. The model is used and demonstrated for a narrow-body aircraft optimization.

The aviation industry is faced with overcoming dual challenges of achieving net zero emissions by 2050 while meeting both performance and increasingly stringent noise requirements. Electrification of aircraft paves a pathway to sustainability, and key enabling technologies offer both opportunities and challenges with respect to acoustic characteristics. This paper presents an integrated analysis methodology to assess the acoustics of air transports that include aspects of electrified propulsion and novel propulsion integration within a multidisciplinary design, analysis, and optimization framework. This approach enables simultaneous evaluations of how noise constraints impact aircraft design in the conceptual design phase. Results of assessment of different air transport categories demonstrate how acoustics trade with other performance characteristics of these vehicles.

Technology assessments are developed to provide context for the design of novel electrified aircraft under the NASA Advanced Aircraft Concepts for Environmental Sustainability (AACES) 2050 program. This work builds on previous development of the market, geopolitical, and economic components of scenarios by adding technology assessments for energy storage system, electric machine, power distribution system, and gas turbine technologies relevant to the development of electrified aircraft. The performance of these technologies was quantified through figures of merit and forecast to 2050 for the three scenarios considered, enabling assessment of the viability and utility of proposed aircraft concepts across the range of future scenarios and their associated technology levels.

Electrified aircraft designs require thermal management systems (TMS) to maintain all electric propulsive components at safe operating temperatures. Modeling the TMS for inclusion in the study of such aircraft from the early stages of conceptual design is required to properly evaluate the feasibility and performance of such aircraft configurations. This work presents a tool-agnostic, multifidelity TMS modeling methodology that is capable of representing TMS architectures in a unified way. The methodology is implemented in an existing MDAO framework, which is built on top of NASA's Aviary aircraft design code and OpenMDAO. The results are validated against literature for several aircraft size classes. The impacts of TMS architectures and subsystem performance parameters on aircraft weight, drag, and power consumption are presented. Trade studies show that ducting losses, heat acquisition effectiveness, plumbing layout, and electrification factor are major influences of system level performance. Neglecting these effects during early design stages can create additional challenges to realizing the benefits of electrification at later design stages.

Aircraft that incorporate novel technologies have the potential to unleash step changes in energy efficiency. These novel aircraft are highly integrated, can take advantage of electrification and closer airframe-propulsion integration, and leverage complex interactions between subsystems and new possibilities for aircraft operations. To support the need for advanced aircraft conceptual design studies, we develop and integrate a series of subsystem models in a multidisciplinary design analysis and optimization (MDAO) framework. Our framework, built upon NASA's OpenMDAO and Aviary, leverages gradient-based optimization to efficiently explore the expanded aircraft design space that new technologies offer. The framework includes component models of various subsystems, including electrified propulsion, batteries, thermal management, aerodynamics, and aero-propulsive interactions. This paper presents the system-level integration of these subsystem models into an aircraft-level MDAO framework. We demonstrate its application to the conceptual design optimization of electrified aircraft for single-aisle and commuter classes. This MDAO framework will be made open source to contribute to ongoing research on next-generation aircraft design and sustainable aviation.

This paper presents the Library for Unified Conceptual Aircraft Synthesis (LUCAS) sizing and optimization framework, which is largely based on Stanford’s Stanford University Aerospace Vehicle Environment (SUAVE). LUCAS is applied to a commuter mission carrying 19 passengers. Results show that energy usage benefits depend on mission range and electrical component technology and that reserve requirements play a significant role in the feasibility of electrified aircraft. It is found that storing more energy in batteries rather than fuel reduces the mission energy requirement at the expense of aircraft weight growth. All-electric aircraft could provide onboard energy savings of upward of 30% for a 180 km mission, but this would only become feasible if battery specific energy reached the high value of [Formula: see text]. Range could be increased to 550 km if part of the reserve mission requirements is relaxed. Under more realistic technology assumptions, a hybrid design storing energy in fuel and batteries could fly commuter missions with energy savings of 6%. A beneficial use case of hybrid configurations is a mode of operation where the aircraft uses only batteries during the main mission and fuel to store all the reserve energy. If reserves are not required for a particular flight, energy savings are still maximized, while the availability of fuel ensures certification requirements are met with fewer penalties.