Structural Power Performance Targets for Future Electric Aircraft

Structural Batteries for Aeronautic Applications—State of the Art, Research Gaps and Technology Development Needs

Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon-neutral aircraft, with hybrid-electric aircraft due to be delivered after 2035, initially in the regional aircraft segment of the industry. Electrical energy storage is one key element here, demanding safe, energy-dense, lightweight technologies. Combining load-bearing with energy storage capabilities to create multifunctional structural batteries is a promising way to minimize the detrimental impact of battery weight on the aircraft. However, despite the various concepts developed in recent years, their viability has been demonstrated mostly at the material or coupon level, leaving many open questions concerning their applicability to structural elements of a relevant size for implementation into the airframe. This review aims at providing an overview of recent approaches for structural batteries, assessing their multifunctional performance, and identifying gaps in technology development toward their introduction for commercial aeronautic applications. The main areas where substantial progress needs to be achieved are materials, for better energy storage capabilities; structural integration and aircraft design, for optimizing the mechanical-electrical performance and lifetime; aeronautically compatible manufacturing techniques; and the testing and monitoring of multifunctional structures. Finally, structural batteries will introduce novel aspects to the certification framework.

Design of Batteries for a Hybrid Propulsion System of a Training Aircraft

In this article, we propose the parameters of a battery that would be suitable for the conceptual design of a small training aircraft. The mass design of the battery is based on the requirements for real training flights performed by students in pilot training. Such a serial hybrid propulsion aircraft could be used in our UNIZA aviation, training and education center for pilot training. Due to socio-political pressures in reducing emissions generated by vehicles, there has also been massive research in the aviation industry in the field of hybrid and electric aircraft propulsion. In the introduction, the article deals with the energy sources used in aircraft propulsion. In hybrid propulsion, a combination of aviation fuel and electricity is used as the energy source. The required total energy must choose a suitable combination of these two energy sources. The biggest drawback of batteries that can be used in hybrid systems is their low energy density. Low energy density means that larger and heavier batteries need to be used to achieve the required performance, which is their main disadvantage. Therefore, it is necessary to find a suitable compromise between the hybrid’s percentage, i.e., the ratio between conventional and electric drive. We applied the hybrid aircraft system’s calculations to the real training flights to determine the necessary parameters of the hybrid aircraft suitable for pilot training. This calculation will help in obtaining an idea of the basic parameters of the hybrid drive and the battery parameters, which are necessary for particular applications in the training aircraft. The performed calculations of the hybrid configuration and, especially, the determination of the battery of the hybrid propulsion parameters provide the basic information necessary for the design of the hybrid system of a small training aircraft. These outputs can be used to determine the parameters of batteries that would be used in hybrid systems. A limiting factor to consider with hybrid aircrafts is that the aircraft must be charged on the ground before the flight, which poses interesting logistical and infrastructure problems at the airport.