Hybrid electric aircraft: state of the art and key electrical system challenges

In both Europe and the USA, the aerospace sector is actively pursuing revolutionary design concepts to further improve the environmental impact of air travel. This is partly a result of increasing pressure on the industry from government and other organisations to reduce emissions , despite the continuing increase in air traffic [1] . The aggressive targets set by NASA and the EU [1, 2, 3] (e.g. the Advisory Coun cil for Aviation Research and Innovation in Europe has a target of a 75% reduction in CO2 emissions and a 90% reduction of NOx emissions by 2050) cannot be achieved through marginal improvements in turbine technology or aircraft design. Rather, disruptive technologies and more innovative aircraft must be considered.