Why can stealth aircraft be invisible?

Stealth aircraft can "stealth" mainly by adopting a series of stealth high-tech, including stealth materials of fuselage and skin, stealth coating materials on the surface, stealth structure in appearance, infrared radiation reduction technology, noise reduction technology and electronic interference technology. There are several stealth materials for making stealth aircraft skeletons and skins. The most commonly used materials are carbon fiber reinforced resin composite, carbon-carbon composite with carbon fiber and carbon matrix, silicon carbide wire reinforced aluminum composite and so on. These composites are light in weight and can absorb radar waves. A honeycomb sandwich material is also used as the lining in the skin of the American B-2 stealth bomber to further improve the body's ability to absorb radar waves. In order to obtain the perfect stealth effect as much as possible, the outer surface of the whole fuselage is coated with a layer of nickel-cobalt ferrite or a stealth coating composed of ultrafine powder of metal and metal oxide. This coating can increase the magnetic loss of radiated radar waves and play the role of absorbing and transmitting radar waves; There is also an alkali salt coating called Swankijeff, which can quickly convert radiated radar waves into heat energy and no longer produce reflected waves.

In addition to using stealth materials to make the body of stealth aircraft, its peculiar shape and structure are also a key to aircraft stealth. The cylindrical fuselage of conventional aircraft and the connecting structure of fuselage, wing and vertical tail at right angles to each other can make radar waves incident in different directions generate reflected waves and return them to the radar receiving antenna. Stealth aircraft designers have found that if the cylindrical fuselage is changed into a special-shaped fuselage with rhombic, conical and helmet-shaped cross sections, or the connection between the fuselage and the swept wing is made smooth transition, a special type of aircraft with integrated fuselage and wing will be formed, the tail wing will be cancelled, the inclined V-shaped double vertical tail will be used, and no pylon with missiles will be installed under the fuselage and wing. , can play the role of destroying radar waves and reduce the echo to the weakest or even almost none. Stealth aircraft F- 168. The B-2 stealth bomber has a wingspan of 52.43 meters and a fuselage length of 2 1 meter. The radar cross section of such a large plane is only 0.05 square meters, and the stealth efficiency is very high.

Because the equipment for detecting aircraft includes infrared detector besides radar, stealth aircraft is invisible to infrared detector and radar. The way is to set the air inlet and air outlet of the aircraft engine at the top of the aircraft, and install an exhaust machine and a heat absorption device at the air outlet, so that the high-temperature jet can suck in cold air before it is discharged and quickly cool down, reducing the heat source of the engine nozzle and preventing the infrared detector on the ground from detecting the infrared radiation of the aircraft. The noise generated by aircraft flight can be solved by providing sound absorption devices or designing engines with particularly low noise.