How many years people have been at war with each other, as many dream of becoming invisible to the enemy. From time immemorial, there have been such army attributes as camouflage, camouflage and other military tricks aimed at remaining unnoticed.
It is known: the one who noticed the enemy first has a serious advantage. But it is one thing when the warring parties are following each other with the naked eye or with the help of simple optics, and quite another when the fight is against an enemy tens and even hundreds of kilometers away. Since the middle of the 20th century, radio-electronic and acoustic locator devices have come to the aid of the human eye. They are always on guard, and it seems that it is impossible to hide from them. However, the confrontation between the sword and shield, armor and projectile never stopped: scientists and engineers are persistently looking for ways and means to allow military equipment and soldiers to evade the all-seeing eye of the enemy. In the course of this research, the idea was first born, and then the stealth technology based on it materialized. She became the very "shield" - protection from the "sword", which is the radar radio signal. The technology got its name from the English stealth, translated into Russian as "cunning" or "stealth". So what is the essence of this clever novelty?
Breakwaters
The principle of operation of the radar is that the radio signal sent by the antenna of the radar station (radar), hitting any surface (be it the body of an aircraft, ship or rocket), is reflected from it. Aircraft fuselages, designed primarily with regard to aerodynamic requirements, are usually streamlined, that is, rounded. The radio signal encountered with them, reflected, scatters in all directions. Thus, one of the reflected beams returns to the radar antenna and is captured by the receiving station installed there. The equipment automatically calculates the travel time of the signal to the target and back and thus determines the distance to the object, its coordinates and movement parameters: height, direction and speed. Obviously, the radar signature of any object depends onhow well and in what directions it reflects radio waves. The degree of visibility is determined by the value of the effective scattering area (ESR) - the ability of an object to scatter an electromagnetic wave. Each of the aircraft has its own RCS value. For example, the American giant, the eight-engine B-52 bomber, has an RCS of 100 sq. m., and a conventional fighter is only 3-12 sq. m.
Russian trace
In 1966, the Soviet physicist Pyotr Ufimtsev published an article in one of the scientific and technical journals in which he expressed the idea that an aircraft made of special materials with a special coating, the fuselage of which has faceted rather than round shapes, can become almost invisible to the radar. This article became interested in a radar specialist from the American firm Lockheed, which was working at that time on a new generation aircraft - a high-altitude reconnaissance aircraft and an interceptor. The new car was supposed to be invisible to enemy radars. And it was during its creation that the ideas of the Soviet physicist were first applied in practice. By the mid-70s of the XX century, US aviation received the SR-71 Black bird reconnaissance aircraft, the fuselage of which, in addition to a special coating, was distinguished by an unusual shape that significantly reduced the reflective surface. Inspired by successthe Americans immediately set about developing new types of stealth combat aircraft. By the way, Ufimtsev himself soon moved to the States, where he began to promote technologies based on his idea.
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In early 1977, it first took to the air, and in 1983 the first stealth fighter, the F-117A Have Blue, was adopted. Soon the Pentagon ordered a new strategic bomber with stealth technology from Northrop. After 5 years, the US Air Force received a B-2 Spirit heavy bomber. He, like the F-117, received the baptism of fire in 1991 during the war in Iraq. Then their appearance and combat use caused a furor. The aircraft was presented as a visible demonstration of modern methods of air warfare and the general military power of the United States. At the end of Operation Desert Storm, US Air Force Deputy Commander John Welch said, “Stealth technology has brought us back to the fundamental principle of warfare called surprise. If you can get the surprise effect, you have a big advantage."
Invisibles in the sky
Today, in all industrially developed countries that have their own military aircraft industry - Russia, the United States, the European Union countries, China, Israel, Turkey, India, Iran and others - practically all new developments of combat aircraft, cruise missiles and unmanned aerial vehicles are carried out using stealth technologies … In addition to the already mentioned American vehicles, the following are in operation: the B-1 Lancer (Ulan) heavy bomber, the F-15 Silent eagle (Quiet Eagle) fighter and others. In Russia, stealth technology is used in the modernization of such machines as the Tu-160 bomber, the Su-34 fighter-bomber, as well as the MiG-29SMT fighter, in which, due to the use of radio-absorbing coatings, it was possible to lower the EPR to 1 sq. m.
It should be noted that it is very problematic to effectively use all the capabilities of stealth technologies when modernizing aircraft created many years ago. The necessary significant change in the external contours of these machines is in conflict with the requirements of aerodynamics, deviation from which inevitably leads to a decrease in the main tactical and technical characteristics of aircraft, such as flight speed and maneuverability.
And in the sea
Stealth technology is used not only in the creation of aircraft. In the submarine fleet, enemy sonars (underwater locators) are fought by radically reducing noise and using a special rubber-like coating. In surface ships, the streamlined forms of deck superstructures, towers, etc. are abandoned, and special coatings are applied to everything above the water that absorb radio waves.
The USA, France, England, Norway, China and, of course, Russia are building their warships using stealth technologies. These are mainly ships of small and medium classes: artillery and missile boats, patrol ships, corvettes and frigates. The US Navy recently commissioned a futuristic stealth warship, the LM-2. The Russian first-born, created with stealth technology in mind, was the Steregushchy corvette, built in 2007 at the shipyards of St. Petersburg. Now he is a regular participant in naval parades on the Neva, and the audience has probably already noticed the unusual angularity of his forms, especially the bow artillery mount.
Radar against stealth aircraft
Modern radars (for example, the Russian "Irbis" or "Zhuk") are able to distinguish targets by size and type, that is, to determine what came into their field of vision: a passenger airliner, combat aircraft, helicopter, missile or drone. The command of the Russian air defense forces declares that at present the invisible devices produced abroad, created taking into account stealth technologies, are not invisible to domestic radars. Such aircraft are successfully detected and accompanied by our observation stations. However, nowhere is it mentioned the distance at which the invisibility is detected, nor the number of targets that Russian radars are able to track simultaneously.
Form matters
The goal of stealth technology is to reduce the RCS of an object as much as possible. This is achieved in two ways: firstly, due to the maximum possible absorption of radio emission by the surface of the aircraft or ship, and secondly, by directing the reflected signal anywhere, but not to the radar antenna. The first is achieved through the use of a special coating, and the second - by giving the body not rounded, but broken shapes. Thus, a fighter made using stealth technology has an EPR of no more than 0.5-1 sq. m. True, this has to sacrifice ideal aerodynamics.