First look: Future flight
Look, ma, no moving parts (almost)
- There are 19 scientific studies detailing the ionocraft itself and contributors of related research total 45 scientists from around the world.
- The field of study using electrically accelerated ions is called electroaerodynamics.
- There must be an enormous increase in efficiency before ionocraft are practical. The test craft lacks range, endurance, and payload.
What is an ionocraft?
You may not have heard the word ionocraft before, but it has been around since the 1920s and has been familiar to amateur model makers for decades. Most often the models, shown in various videos on YouTube, were triangular and merely lifted vertically into the air several inches when voltage was applied. There were tiny wires at the top and sheets of tin foil at the bottom. One unlucky experimenter discovered his computer turned on by itself and the home light switches sparked every time he applied current to his model.
Another experimenter built a model of the Federation Starship Enterprise, placing small electrodes at the front and larger ones at the back of the two engines. That worked, moving the model as though it was on a merry-go-round. It was attached to an arm mounted on a pole. Like the triangular models, it was attached to electrical wires instead of flying free as did the MIT model.
Ion engines are already used in space, once the launch is performed by chemically fueled engines. The spacecraft Dawn that visited planets in the asteroid belt starting in 2007 had three 12-inch ion thrust units. It was retired in 2017 and is spending its golden years in an uncontrolled orbit around the dwarf planet Ceres.
Since there is no air in space, the engines required a gaseous fuel called xenon, but it was used sparingly. While the ion engine took four days just to reach 60 mph, it can achieve the speed of the Delta rocket that took them into space over the total mission lasting thousands of days.—AKM
No messy chemicals were burning, just atomic particles spitting out of shuttlecraft fusion reactors. If only that were real. Massachusetts Institute of Technology’s Steven R.H. Barrett had loved Star Trek as a kid—and had the brainpower to attempt to fly an airplane with no moving parts. So, he did exactly that in 2018 with the help of graduate students for eight or nine years at MIT. He was also aided by scientific research found in about 20 papers written by teams of scientists.
Barrett's first calculations were made many years ago on a napkin in a hotel during a bout of jet lag, as reported on the science-news website Seeker. The calculations told him that what everyone thought was impossible. An airplane without conventional engines or propellers is possible.
Barrett and a team of researchers flew a 5-pound aircraft with a 16-foot wingspan at 10 mph across an MIT gym until it ran out of room and had to land. It looks like a model airplane but has “solid-state” engines. It is called an ionocraft because it is propelled by a stream of ions generated by high-voltage electricity, which travels from one electrical contact, the emitter, across a small expanse of air to another, the collector. The ions, during their short trip, bang against innocent bystander (neutral) atoms on the way, providing thrust. (“Officer, I was just floating there when this crazy ion came charging into me from out of nowhere,” a neutral atom might say.) Particles move backward and the aircraft moves forward.
The only problem is that the MIT aircraft can’t take off by itself: not enough acceleration. For launch, the MIT aircraft came whipping out of a slingshot contraption, but after that it flew smoothly, sometimes climbing slightly along its path. A special battery in the nose provides a current that is amplified to 40,000 volts.
What can a silent drone-size aircraft do? Surveillance comes to mind, and Lockheed Martin was reported by MIT in 2013 to be looking at the technology. There’s little to no heat signature as well, so forget using a heat-seeking missile to bring it down. There are a couple of problems: The ionocraft generates ozone, and a fleet of Amazon package-delivering drones just might foul a city’s air. Also there may be a tiny blue glow, thus revealing its presence to enemies.
The silent engines require a sharp emitter, like a small wire, and a larger collector, such as the thicker airfoil shape used on the MIT model. Ions from the smaller wire rush toward the larger collector.
Could the engines ever be large enough to provide power for an airliner or cargo aircraft if that pesky takeoff problem can be solved? It is just barely possible, but estimates are that such an achievement could not occur for another 50 to 100 years. Drones are the likely earlier use of the technology. While the MIT model has a conventional elevator and rudder for remote control, it is also possible the aircraft can be made without them. Then it would truly have no moving parts.
Some of the first 10 MIT flights were nearly twice the distance that the Wright brothers flew in 1903. At that time there seemed no use for a flying machine that could carry only one person and travel little more than 100 feet. The ionocraft has made the same impression.
Maybe our future Mars-bound Enterprise will have shuttlecraft powered by ion engines, or maybe it will be fusion reactors, but one version of engines that could power it is now on the drawing board.
In our eightieth year, AOPA is looking back to our roots and ahead to our future: What will aviation look like in the next 80 years?
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