1. Background
Electric aircraft concepts and demonstrators have become increasing more popular in the past decade. Environmental awareness across the world has been one motivator for this movement towards the electrification of flight. With over a quarter of the global greenhouse emissions originate from the transportation economic sector, and a substantial portion of those are due to aerial traffic, a significant impact may be made by decreasing the amount of fossil fuel used in aircraft. Electric airplanes show great potential not only to reduce carbon emissions, but also acoustic pollution when compared with conventional planes. A shift from traditional jet engines to more electric propulsion may be the answer to a quieter sky. In addition to these benefits, the operating costs associated with electric aircraft may be lower once the technology matures. The largest expense for airliners is fuel, leading to a reasonable benefit to a 1 transition since electricity is less expensive than jet fuel.
With recent advancements in enabling technologies across multiple engineering disciplines, the development of electric transportation available for both the private and commercial aviation industries is becoming more viable. However, there are still many challenges that must be overcome. In the process of transitioning from traditional combustion propulsion, be it jet engines or propeller driven aircraft, significant redesign of the power system is required. Mass is one key aspect of many that must be considered in this process. In the case of combustion propulsion, the primary fuel has an energy density on the order of 11kWh/kg. For comparison, Lithium-Ion, the leading battery energy storage chemistry, has an energy density on the order of 0.3kWh/kg. Additionally, unlike a conventional system, fuel mass is not burned throughout the flight, so more energy is required for the same flight. In order to ensure that an all-electric or partially electric propulsion system meets an aircraft’s mission objectives, special care must be taken in every aspect of the design process, from system architectures to subsystem components.
