Before our very eyes, electricity is starting to play an increasingly important role in transport. Following the electric vehicles, which are successfully reclaiming their place on the roads, electric airplanes rise into the sky. But for aviation, such changes could have far-reaching implications. It is quite possible that the planes of tomorrow will lift not electric motors into the sky, but atmospheric ion engines. The appearance of ionic aircraft promises a qualitative breakthrough in aviation technology.
What it is?
Today, an ion plane, also known as an ionocraft (or a lifter, with an emphasis on the last syllable), is only a light flying model that can instantly break away from the surface as soon as an electric current is applied to the wire connecting it to the power source. But for engineers and science fiction writers, this is one of the options for the aircraft of the future, which has very tempting characteristics. It will be environmentally friendly, in contrast to modern airplanes and helicopters, silent and without significant efforts will be able to take off and land vertically. In any case, this is how the researchers represent him. Is this the technology for the flying cars of the future?
The lifting force in such an apparatus is created due to the Biefeld-Brown effect. Back in the 1920s, American scientists Thomas Brown and Paul Biefeld, who assisted him, experimented with Coolidge's X-ray tubes, discovered an unusual effect. A certain force acted on an asymmetric capacitor charged to a high voltage. It was enough even to lift the condenser into the air. The scientist himself was at first confident that he had found a way to influence gravity using electricity. Then, the discovered phenomenon was even given the appropriate name - "electrogravity". Today, such experiments are popular not only among schoolchildren and students who are fond of physics, but also among supporters of various theories that are not recognized by modern science. In their opinion, the ionic wind gives only 10-20% of the thrust of the ion engine, the rest is given by the force not yet known to science.
But only if it was in gravity, and not in the movement of charged air ions, as it really is, then the device would work equally well both in air and in a vacuum. But as a result of many experiments, it was found that in the absence of a gas environment, the device does not work. In a vacuum, the effect disappears. Ionolet (atmospheric ion thrusters) should not be confused with ion thrusters, which are increasingly used in spacecraft. They are just designed to work in a vacuum. Such an engine works freely in an airless environment, since the jet thrust arises on the basis of the stored working fluid, which, as a rule, is an inert gas (argon, xenon, etc.). The spacecraft is refueled with it before launch. In the case of an ion aircraft, its working medium is actually outboard air, which, of course, does not need to be taken with you on the flight.
The secret of the lift force of an ionic aircraft is simple. At very high voltages between the electrodes - anode and cathode - an ionic (or electrostatic) wind occurs. This phenomenon is also called the electrohydrodynamic effect (EHD).Moreover, one electrode is usually thin or sharp, the other is wide and flat. That is, they are not symmetrical to each other. Thus, a levitating asymmetric air condenser is obtained.
Air molecules ionize near a negatively charged electrode. They receive a negative charge and begin to move towards the positively charged electrode. At the same time, they carry away neutral air molecules on their way, which creates the necessary thrust for flight. Moreover, complete ionization of the air passing through the apparatus is not required.
The simplest scheme of an aircraft is as follows. Negatively charged electrodes are metal points. There are several of them, and they are located above a metal grid with a positive charge. The ions formed between them rush to the grid, where they part with their charge, leaving the engine with ordinary air molecules. Thus, high voltage electricity is converted into kinetic energy of the air flow. This ion engine is also called electrostatic propulsion (ESM).
By adjusting the voltage on the electrodes, you can give the command for takeoff and landing, changing the voltage only on some of the electrodes, you can tilt and turn the apparatus. And at the same time, the engine on the ionic wind does not have any moving parts. The design is simple, and promising propulsion options do not imply serious maintenance, lubrication, etc.
It is believed that the term "ionocraft" itself, in the Russian version "ionolet", was invented by our compatriot. Aviation pioneer, ace pilot of the First World War, who left Russia after the revolution, aviator, inventor and aircraft designer Alexander Nikolaevich Prokofiev-Seversky. He also received a patent for his aircraft in 1964. Over the years spent in America, Seversky worked as a consultant to the Ministry of Defense, founded two aircraft building firms, designed several successful aircraft, and became the author of many inventions and patents. However, he never achieved commercial success. In 1939, Seversky was removed by investors from the management of the company he founded. After which he took up writing, lecturing and thanks to his ability to speak in public he became widely known, and in the 60s he took up ionolets. Seversky described in detail the physics of the effect and patented the basic principles of the ion-plane operation.
The model, created by Seversky, was a rectangular frame made of balsa (wood, the wood of which is considered the lightest in the world) with an aluminum wire stretched over it. Electrical energy was supplied to the apparatus via a coaxial cable. But he failed to do anything more. Seversky's attempt to build an ionocraft capable of taking off with a person on board failed. Formally, due to lack of money. Still, the main difficulty in creating such an apparatus lies elsewhere. Even now, models of ion aircraft are not capable of carrying their own power source. All models are connected to an external power source, since they cannot yet lift their own, let alone a pilot or additional equipment.
Not so simple
What's the problem? The atmospheric ion thruster requires a very high voltage current. At the same time, not so long ago, the idea of an ion flight was returned again. And not just anyone, but researchers from the Massachusetts Institute of Technology (MIT), which is known to be an innovator in the field of promising technologies. According to their findings, it will take several hundred or even thousands of kilovolts to lift an unmanned vehicle with equipment on board and its own power source into the air. For comparison, in a household eclectic network, the current voltage is 220 volts. This is only 0.22 kilovolts.A lightweight experimental model of an ionic flight made at the MIT laboratory required a voltage of only a few kilovolts. A thin copper wire was used as a negatively charged electrode, and a light aluminum tube was used as a positive one. The frame was glued from balsa.
But on the whole, the results of the experiment were encouraging. They showed that engines based on the Biefeld-Brown effect can be much more efficient than traditional engines. Experiments have shown that the thrust of such an atmospheric ion engine can be up to 110 Newtons per kilowatt of power, while traditional jet engines have an indicator of only 2 Newtons per kilowatt.
But there is another difficulty in creating such devices. In comparison with traditional jet engines, atmospheric ion thrusters are significantly inferior in terms of “density” of thrust, that is, its amount per unit of working area. This is explained by the fact that its value directly depends on the width of the air gap between the anode and cathode. The larger it is, the stronger the craving. Therefore, to create even a light aircraft, it will be necessary to place the electrodes at a great distance from each other. In fact, such clearances will be determined by the maximum possible dimensions of the aircraft. Thus, the fuselage itself, surrounded by electrodes, will be inside the electrostatic propulsion device.
If you believe the promises of the researchers, such a device will be able to move silently and will not have harmful emissions. In addition, it will be able to take off, land, and hover vertically. In this he is like a helicopter. But, unlike the latter, the absence of vibration will create ideal comfort in the passenger cabin. Such devices will be able to take off and land in the immediate vicinity of residential and office buildings, without creating noise, and, consequently, inconvenience to others. In the past, such aircraft were thought to be manned, but now with the development of unmanned technology, we can say that the first ionic aircraft will do without a person on board.
He will be indispensable in military service. The ionolet is invisible in the infrared range, which is a real godsend for the military. Such an unmanned aerial vehicle can be used for reconnaissance and other missions without risking being detected by a night vision device. The ion-plane can also be implemented in the form of a levitating platform that receives power from the ground via wires. Flying construction crane, drone for traffic patrolling, weather balloon that monitors weather changes. It can be used in many ways.
Ion aircraft can also be useful for flights in the atmosphere of other planets. After all, they do not need to carry fuel on board. But still, it remains to resolve the issue with a powerful power source.
Do it yourself
If you have experience with electricity, you can make the simplest flying model of an ionic aircraft yourself. In this case, it is necessary to take appropriate precautions, since you will have to work with high voltage currents. The design is based on a triangular frame glued from thin balsa strips. The upper electrode is a thin copper wire with a cross section of 0.1 sq. mm. The bottom one is a wide strip of food grade aluminum foil stretched over the frame. The distance between them is about 30 mm. The foil must bend around the strips and not have sharp edges, otherwise electrical breakdown may occur.
After assembling the structure, a high-voltage power supply with a voltage of 30 kV is connected to it. The positive lead to the wire, the negative lead to the foil. To prevent the model from flying away, it must be tied to the table with nylon threads.