Engineering: Flight of the silent, solid-state aeroplane

The flight of a small aircraft with a solid-state propulsion system, as opposed to an engine with moving parts, is described in a paper published this week in Nature. These findings open up possibilities for aircraft that are quieter, mechanically simpler, and do not emit combustion emissions.

Historically, aircraft have been powered by engines with moving components, such as propellers or turbines, and typically rely on fossil fuel combustion. Electroaerodynamic devices, which create thrust by using electrical forces to accelerate ions in a fluid to form an ionic wind, have been proposed as an alternative method for propelling aircraft. However, no such aeroplane has flown before.

Steven Barrett and colleagues have designed and flown a small fixed wing aeroplane with an electroaerodynamic system of propulsion. The aircraft, which has a five-metre wingspan and weighs 2.45 kilograms, is powered by a custom system containing a battery stack and high-voltage power converter that can produce around 500 watts. The aeroplane successfully flew 60 metres in an indoor space over the course of ten test flights, with an average flight altitude of 0.47 metres. Its thrust-to-power ratio was comparable to that achieved by conventional propulsion systems such as jet engines, although the overall efficiency was lower. The authors report that this specific aeroplane design prioritized small size over high efficiency, but that future designs can improve efficiency.

The authors conclude that these initial test flights for an electroaerodynamic-powered aeroplane compare favourably to early flights of aircraft propelled by moving parts.