You may have heard about "lifters" or "ionocrafts," in science fiction stories discussing fake worlds, or on message boards discussing the real world. They exist in both worlds, but they're only really practical in one.
How An Ionocraft Works
Electrons are slippery little things, but most of the time the atoms in the air have a good hold on them. Given the right combination of circumstances, however, any atom can lose its grip on its outermost electrons. Enough heat can loose electrons. Radiation can knock electrons off an atom. Exposure to a relatively powerful electric field can rip electrons off an atom.
Ionocrafts work by using the last mechanism. A corona wire is strung at the top of the craft, and is charged with a very high voltage. The atoms of air around it lose their electrons and become positively charged. This alone doesn't do much, but below the wire, with plenty of air between the two, is a collector. The collector is a negatively charged plate or foil that attracts the positive ions.
On their path to the collector, the ions will knock into the air molecules in their way. Because they are moving downwards, they will push the air molecules down. If enough ions are on the move, a large amount of air will be forced down. In response, the craft will be forced up. Most ionocrafts waft around on a gentle breeze.
Building an Ionocraft
Then again, most ionocrafts weigh only a few grams. A well-built ionocraft will need about one watt of energy per gram of weight, so keeping it light is essential. There are many tutorials on how to build them, and a basic design takes only an afternoon. Most ionocrafts, or lifters, are basic triangular or hexagonal balsa-wood frames. The wire is wrapped around the top of the frame, and the foil collector around the bottom, with a good air gap between them. (There also needs to be a heat insulator between the wire and the wood.)
The difficult part of making a functioning ionocraft is getting a good high voltage power supply that can charge up the wire. While the glider material itself is cheap, the power supply is quite a bit more expensive. It's also the main reason we get why ionocrafts might not be a great idea. Touching the wire of even a small craft can give you an unpleasant shock. Touching the wire of any craft that could lift a human weight would kill you.
That being said, if you want to make a small glider, there's a pretty good tutorial right here.
The Ionocraft Controversy
Plenty of people are interested in making ionocrafts at the moment, because while the ion wind theory is generally accepted, there are plenty who think that ionocrafts employ forces that might revolutionize both physics and transportation. Thomas Townsend Brown, a gifted inventor and scientists, believed that ionocrafts displayed some kind of anti-gravitational force, and spent much of his life designing these "lifters." If ionocrafts manage any kind of anti-gravitational force, it seems to be contingent on their being in an atmosphere, as ionocrafts do not lift up in a vacuum.
They also have more drawbacks than mere death by electric shock. Not all ionized air particles are harmless. Those who have been around a lot of lightning strikes will know that lightning when lightning ionizes the air it leaves behind ozone. So do ionocrafts. Ozone, along with heating the planet, rips apart the tissues of the respiratory system. Exposure to even a little is bad news. Having full-sized crafts creating ozone would do a lot of damage to both people and the planet.
Still, ionocrafts are neat things to study, or just to gawk at. If you get a chance to see one (in a well-ventilated room), go take a look!