Electric device is first of its kind to fly in atmosphere, and opens up new ionic wind propulsion paradigm
Electrical engineering students at the State University of New York Oswego (SUNY Oswego) developed the rotorcraft-type flying propeller as part of investigations into corona discharge and ionic wind, an effect which has been known since the 18th century. The team, directed by Adrian Ieta, a member of the electrical and computer engineering faculty, are now pursuing a patent on the technology, which they believe could open a new field of technological development.
Ionic wind is generated when a high voltage is applied between asymmetric electrodes in air, stripping electrons from gas molecules and creating charged ions in an electric field. If one electrode has a sharp edge, the result is a flow of air. “The ions are accelerated by the electric field and in their collisions with neutral molecules create an overall movement of the air from the sharp electrode to the counter electrode also known as ionic wind, corona wind or electrodynamic (EHD) flow,” Ieta explained.
This effect was first noted in 1709, and first used to make an object spin in 1760, but the SUNY Oswego team is the first to translate that movement into flight. Previous experiments with ionic wind aircraft have looked at fixed-wing models. “I think our research is unique in many ways,” Ieta said. “I think it’s now easy to make ionic rotors, and fairly easy to optimise ionic propellers and make them fly. It’s just that nobody thought of it the way we did.”
The team’s innovation is in using a metal cylinder as the counter electrode around a propeller whose aerofoils acted as the sharp electrode. The emitter electrodes on propeller edges were made from copper tape and pins, while a voltage is applied along the shaft. The cylinder intensifies both the electric field and the ionic wind it generates. The propeller spins around the shaft running down the axis of the cylinder, lifts up the shaft and flies away. “This was the first rotational object to lift using this technology,” Ieta said. “It might be the first ionic system to ever lift off in atmosphere without carrying a power supply.”
Ieta worked with students whose interest had been sparked by a demonstration he had organised for local high schools. “I let them do what they wanted to try,” Ieta said. “What they most appreciated was the less structured environment and the opportunity to pursue whatever their imagination came up with.” Six undergraduates came up with prototype propeller designs, with the first, designed by Nicholas Curinga, achieving lift off in February 2018.
Ieta believes it is particularly notable that the engine powering the flight is effectively the propeller itself. “It’s a completely different approach to propulsion,” he said. He presented the research at a recent conference on electrostatics, following publication of a paper in the Journal of Electrostatics.
Commenting on the research, Stephen Wood, associate director of innovation and entrepreneurship at the SUNY research foundation, praised Ieta’s “tenacity and drive to innovate in this field,” which, he said, showed how even well-known phenomena can yield interesting engineering results if they are looked at in a new way. “Dr. Ieta’s invention represents the world’s first ionic wind drive for propeller and rotor airfoils and its ingenuity, uniqueness and potential implications for commercial aviation and drone industries cannot be overstated,” Wood said.
Ieta’s team has now started looking at enhancements to the technology, such as using two contra-rotating propellers to amplify the thrust and to lift heavier objects without making them spin. Potential developments might include ionic drones, new types of ionic motor including linear motors, and going back to the original inspiration for Ieta’s student team, scientific toys and demo tools that might capture the attention of future scientists.