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This paper describes the conceptual design of a variable-speed fixed-displacement electric motor pump for aircraft hydraulic systems. In contrast to today's approaches, the pump controls the constant system pressure by adapting the motor speed rather than the pump displacement or both. This concept might increase the pump's part load efficiency significantly. The paper starts with introducing and analyzing the dynamic requirements of aircraft hydraulic pumps and evaluating different pump concepts. The concept of an internal gear pump driven by a permanent magnet synchronous motor is selected. For this concept an experimental prototype is developed. The electric motor pump is modeled and a pressure controller is designed. The prototype is set up and tested on an experimental test bench regarding dynamics, efficiencies and noise emissions. The overall concept is evaluated regarding secondary power demand, system heat load, wear, reliability, noise, and mass.

Fuel cell technology will play a decisive role in the process of achieving the ambitious ecological goals of the aviation industry. However, apart from its obvious environmental advantages, the integration of fuel cell technology into commercial aircraft represents a challenging task in terms of operational and economical aspects. Since fuel cell systems are currently exposed to an intense competition with well-established power sources onboard an aircraft, engineers are in pursuit of highly efficient and particularly lightweight fuel cell systems. Supported by model-based design in conjunction with elaborate optimization techniques this pursuit has led to highly specialized systems. These systems tend to use their components to full capacity, which typically implies marginal system robustness. In consequence, preliminary design studies propose fuel cell systems that are sensitive to partial faults, or even to the slightest deviation, or degradation of their components' behavior.

The All-Electric-Engine with only electrical power offtake is a main goal in aircraft system development. The use of electric-motor pumps instead of engine-driven pumps for powering the central hydraulic systems could be a part of this objective. Additionally, the concept would meet the incremental development strategy performed by the aerospace industry today and saves costs by using state-of-the-art hydraulic actuation technology. This paper describes a process for optimizing such systems regarding their architecture and design parameters. For this task a methodology for the hydraulic consumer allocation called OPAL is used and extended by an automatic power system sizing. Feasible allocations, called permutations, are determined on the basis of preliminary system safety assessments regarding multiple top failure events. In the next step an automated sizing of the permutations is performed based on simplified hydraulic load analyses.