For more than 100 years, aeroplanes have taken flight thanks to engine-based propellers and turbines, mostly powered by fossil fuels. In this week’s issue, Steven Barrett and his colleagues reveal an alternative: a plane powered by a near-silent engine that has no moving parts. Solid-state propulsion systems use electric fields to ionize the molecules in the air, which then collide with neutral molecules, resulting in an ionic wind that generates thrust. It had been thought that thrust-to-power limitations would prevent such systems from propelling planes but the researchers demonstrate this is not so with the sustained flight of a solid-state aeroplane. Weighing 2.45 kilograms, the plane has a 5-metre wingspan and carries a battery stack and power converter that produces around 500 watts. In the test flights, the plane achieved a thrust-to-power ratio comparable to that of a jet engine, although the overall efficiency was lower. This proof of concept opens up possibilities for electroaerodynamic propulsion, which could lead to quieter, low-emissions aeroplanes.
