October 8 2022: It's a wrap. This article concludes our 5-part series on flying electric cars.
How eVTOLS work
The electric version of the Vertical Take Off and Landing craft is powered by Lithium-Ion batteries – the same which power electric cars, buses and bikes on the ground.
eVTOLS have a unique mode of flight: when they take off, they do so in a mode like helicopters, then switch to an airplane mode for the flight and finally revert to helicopter mode for the vertical descent. In this aspect, they operate like drones. Large omnidirectional fans enable the craft to rise and move in any direction.
These fans and propellers harness what is known as “distributed electric propulsion”, that means, the thrust is divided among multiple elements, usually, each with its own motor. This helps to keep the system very light: How? By doing away with heavy helicopter-style rotor blades, the eVTOL also eliminates transmissions, gear boxes, shafts and hydraulics. Eliminating all this hardware makes for a very small craft. This allows it to operate in very small spaces – like parking lots.
Like drones, eVTOLS come with different combos of propellers and wings -- and manufacturers have innovated, to suit their applications. Some eVTOLS have propellers that change direction so that the craft can first lift, then cruise. Others use multi-rotor systems, similar to the quadcopter drone. Most eVTOLS have more than one motor; some work with each rotor, while a separate motor provides forward thrust.
This is still work in progress: no single eVTOL design can be said to be the definitive choice of the future.
Earlier articles in the series:
The full series has appeared as a cover story by Anand Parthasarathy in the October 2022 issue of Science Reporter