2018/11/21: When it comes to moving through Earth’s thick atmosphere, however, “everyone saw that the velocity [from an ion thruster] was not sufficient for propelling an aircraft,” Walker says. “Nobody understood how to go forward.”
But Barrett and his team figured out three main things to make Version 2 work. The first was the ionic wind thruster design. Version 2’s thrusters consist of two rows of long metal strands draped under its sky blue wings. The front row conducts some 40,000 volts of electricity—166 times the voltage delivered to the average house, and enough energy to strip the electrons off ample nitrogen atoms hanging in the atmosphere.
When that happens, the nitrogen atoms turn into positively charged ions. Because the back row of metal filaments carries a negative charge, the ions careen toward it like magnetized billiard balls. “Along the way, there are millions of collisions between these ions and neutral air molecules,” Barrett notes. That shoves the air molecules toward the back of the plane, creating a wind that pushes the plane forward fast and hard enough to fly.
The breakthrough offers a great proof of concept showing ion thrusters can be used on Earth, says Alec Gallimore, an aerospace engineer at the University of Michigan who was not involved with the work. But any such use would likely be in limited capacities. Propellers and jets are still far more efficient than the ion wind thrusters Barrett demonstrated, making it unlikely that passenger planes would switch over anytime soon. But the thrusters have one key advantage: “There’s no sound generation. So [drones] for building inspections or things like that”