Flying Star Trek-style
© Screenshot Youtube MIT / Nature
December 2021

Flying Star Trek-style

By Björn Carstens
In the Star Trek movies, spacecraft powered by ion thrusters dash through the universe. In the United States a rather earthly aircraft recently completed an initial test flight with such a propulsion system. Is it ringing in a revolution in aviation?

Who would have thought that the principle of ion thrusters that many of us are familiar with only from sci-fi movies will soon be 100 years old? As far back as in 1923, the Austrian-German space pioneer Hermann Oberth described his design of an ion drive. However, a few more decades of development work would pass before, in 1998, the first ion-powered spacecraft, U.S. Deep Space 1, would be launched into orbit.

Like conventional rocket engines, ion thrusters, i.e., electrical propulsion systems, are reaction engines. However, their fuel (e.g., ammonia or xenon) is not burned but ionized, in other words electrically charged. The ions are accelerated in electrical fields, creating a highly energetic particle beam whose recoil propels the vehicle.

So far, ion drives have seemed to be suitable exclusively for use in space. The reason is that while they lack sufficient thrust to lift a vehicle off the ground, they do deliver extremely sustainable propulsion power for reaching distant planets. U.S. researchers at the Massachusetts Institute of Technology (MIT) are now planning to “beam” the technology back to Earth and have recorded initial success in lifting off a self-designed ultra-light plane – without the use of kerosene or other fuels, and without propellers and turbines.

  • The ions are accelerated by the voltage between the electrodes (blue-white horiz ...
    The ions are accelerated by the voltage between the electrodes (blue-white horizontal lines). On the way from the front to the rear they clash with air molecules, push them in the process and thereby generate a stream of air © Christine Y. He
  • Design of an aircraft propelled by ionic wind: the system might be usable to pro ...
    Design of an aircraft propelled by ionic wind: the system might be usable to propel smaller drones and even light aircraft, according to MIT researchers – as an alternative to engines using fossil fuels © MIT Electric Aircraft Initiative
Powered by ionic wind

The scientists have published details of their test flight in the science journal “Nature”: Thrust is created by generating ionic wind, for which a very high positive charge of 20,000 volts is applied at the wing front, causing electrons to be extracted from the nitrogen particles in the air. The ions generated in the process are attracted by a negative 20,000-volt charge at the wing curvature and accelerate rearward via the wings. This generates a wind that propels the aircraft.

At the moment, though, the technology is still in a prototype stage. The flying object used in the experiment weighed only 2.5 kilograms (5.5 lbs.) and the maximum altitude reached in the first successful test flight of merely twelve seconds was barely half a meter (1.6 feet). So, real-world operation is still a long way off and even the U.S. researchers doubt that it will be possible to design ion engines capable of propelling passenger aircraft within the foreseeable future. While ion drive technology is unlikely to revolutionize aviation for quite some time, its use in drones might become a reality relatively soon.