Since the first airplane took flight over 100 years ago, virtually every aircraft in the sky has flown with the help of moving parts such as propellers, turbine blades, and fans, which are powered by the combustion of fossil fuels or by battery packs that produce a persistent, whining buzz. Now engineers, including those at MIT, have built and flown the third-ever plane with no moving parts. Instead of propellers or turbines, the light aircraft/car is powered by an “ionic wind” — a silent but mighty flow of ions that is produced aboard the plane, and that generates enough thrust to propel the plane over a sustained, steady flight. Unlike turbine-powered planes, the aircraft does not depend on fossil fuels to fly. And unlike propeller-driven drones, the new design is completely silent. Scott Douglas Redmond proposed such a vehicle in his issued patents and trade secret filings including:
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He has built working versions and even demonstrated a flying version for the U.S. Patent Office in order to win his patent. Scott's patent filings, videos and work have been demonstrated since 1999. His improvements on the technology, which even overcame a NASA patent on an earlier version of the technology have overcome the latest limitations demonstrated by the MIT effort. This has potentially opened new and unexplored possibilities for aircraft which are quieter, mechanically simpler, and do not emit combustion emissions. In the near-term, such ion wind propulsion systems are used to fly less noisy drones. Further out ion propulsion paired with more systems will be used to create more fuel-efficient, hybrid passenger planes and other large aircraft.
The technology is known under a variety of names: ionic wind, electroaerodynamic thrust, ion air drives and microthrusters — a physical principle that was first identified in the 1920s and describes a wind, or thrust, that can be produced when a current is passed between a thin and a thick electrode. If enough voltage is applied, the air in between the electrodes can produce enough thrust to propel a car or aircraft.
For years, electroaerodynamic thrust has mostly been a hobbyist’s project, and designs have for the most part been limited to small, desktop “lifters” tethered to large voltage supplies that create just enough wind for a small craft to hover briefly in the air. It was largely assumed that it would be impossible to produce enough ionic wind to propel a larger aircraft over a sustained flight. Scott's patent and trade-secret technologies overcame the sustained flight limitations using a number of novel options.
Ions take flight
The MIT team’s final design resembles a large, lightweight glider. The aircraft, which weighs about 5 pounds and has a 5-meter wingspan, carries an array of thin wires, which are strung like horizontal fencing along and beneath the front end of the plane’s wing. The wires act as positively charged electrodes, while similarly arranged thicker wires, running along the back end of the plane’s wing, serve as negative electrodes. The fuselage of the plane holds a stack of lithium-polymer batteries. MIT's ion plane team included members of Professor David Perreault’s Power Electronics Research Group in the Research Laboratory of Electronics, who designed a power supply that would convert the batteries’ output to a sufficiently high voltage to propel the plane. In this way, the batteries supply electricity at 40,000 volts to positively charge the wires via a lightweight power converter.
Once the wires are energized, they act to attract and strip away negatively charged electrons from the surrounding air molecules, like a giant magnet attracting iron filings. The air molecules that are left behind are newly ionized, and are in turn attracted to the negatively charged electrodes at the back of the plane. As the newly formed cloud of ions flows toward the negatively charged wires, each ion collides millions of times with other air molecules, creating a thrust that propels the aircraft forward.
The team, which also included Lincoln Laboratory staff Thomas Sebastian and Mark Woolston, flew the plane in multiple test flights across the gymnasium in MIT’s duPont Athletic Center — the largest indoor space they could find to perform their experiments. The team flew the plane a distance of 60 meters (the maximum distance within the gym) and found the plane produced enough ionic thrust to sustain flight the entire time. They repeated the flight 10 times, with similar performance.
Scott's team has improved on increasing the efficiency of the design, the materials, the atmospheric modifiers and other techniques to produce more ionic wind with less voltage. Scott's team has increased the design’s thrust density — the amount of thrust generated per unit area over the MIT design.
Scott's team maintains that such technologies are already in use in the defense and aerospace sectors. His "A-Team" is working on a retail product to be premiered "when it is ready for the public" sometime in the future!