The aircraft’s 22.7kg brushless DC cobalt motor is claimed to be "the most powerful, lightest and most efficient of its type ever produced". The three-phase, 270V, 200A machine is slightly larger than a coffee can, and is said to have an efficiency above 90%. A modular core design allows the motor to be lengthened to deliver more power, or shortened if less power is needed. The picture below shows a view of the motor when the cowling is removed.

Sonex, which has developed the proof-of-concept craft in six months for less than the cost of a conventional aircraft of its type, has also been working on a controller for the motor. Initially, it will use Hall effect sensors to determine the motor’s rotor position, but it is also looking at using the motor’s back-emf to sense the position, thus potentially eliminating the need for the Hall sensors.

The safe boxes that hold the high-energy-density – but volatile – Li-Poly batteries, could be recharged in position on the aircraft, or removed and recharged elsewhere. This would allow them to be replaced with newly charged spare boxes for quick turn-arounds.

"By developing a viable electric motor and controller system for this proof-of-concept aircraft, we will open a door to future flight that we have only been able to dream of," says Sonex’s founder and president, John Monnett. "Self-launching, electric powered gliders already exist," he points out, "but the potential of electric power goes beyond that single use and relates directly to sport flying, aerobatics and high-altitude flight in purpose-built airframes."

Sonex will not be drawn on when a commercial version of its electric aircraft may be available or what it will cost, except to say that it will be "vastly less expensive than other things out there".