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A number of promising technologies to perform ground movements without main engines are currently being researched. Notably, onboard ground propulsion systems have been proposed featuring electric motors in the landing gear. While such on-board systems will help save fuel and avoid emissions while on ground, they add significant weight to the aircraft, which has an impact on the performances in flight. A tool to assess the global benefits in terms of fuel consumption and emissions is presented in this work. A concept of an aircraft-integrated ground propulsion system is firstly considered and its performances and weights are determined, assuming the Auxiliary Power Unit or a zero-emission device like a fuel-cell as power source for the system. Afterwards, a model of the propulsion system integrated into an object-oriented, mid-sized aircraft model is generated, capable of precisely simulating a whole aircraft mission.

Advanced modeling and simulation techniques are becoming more important in today's industrial design processes and for aircraft energy systems in specific. They enable early and integrated design as well as validation of finalized system and component designs. This paper describes the main methods and tools that can be applied for different phases of the energy design process. For demonstration, the object-oriented modeling language Modelica was chosen, since it enables convenient modeling of multi-physical systems. Based on this standard, common modeling guidelines, a modeling library template, and common interfaces have been provided. A common modeling infrastructure is proposed with considerations on additional libraries needed for local tasks in the energy design process. The developed methods and tools have been tested by means of some predefined use cases, which are performed in cooperation with diverse aircraft industrial partners.

Intelligent software functions for energy management form a crucial element for aircraft electrical and thermal systems. In the electrical system, these are currently electrical load or power management functions that can cut and reconnect loads based on fixed priorities. The main aim of these functions is to prevent overload in failure mode of electrical generators, for example if one generator fails and another one has to take over its loads. For more-electric or all-electric aircraft, these functions should also cut loads during normal operation, since the electrical systems will not be sized to simultaneously provide maximum power to all loads. Additionally, energy management functions shall deal with multiple, parallel sources and should split power off-take in a way to reach maximum system efficiency. This paper provides an object-oriented tool and a method that enable a more intuitive development of an energy management function using economic models.