P-750 Grom / Kh-90
The P-750 Grom supersonic winged cruise missile with a range of 3000-4000 km was developed to replace the Kh-55 [AS-15 KENT]. The AS-X-19 Koala was an air-launched land-attack version derived from the SS-NX-24 Scorpion submarine-launched missile. A pair of AS-19 missiles was expected to arm the Tu-142 Bear-H bomber. The history of the X-90 began in 1971. Then developers appealed to the government of the USSR with the construction project of a small strategic cruise missiles that could operate at low altitudes, applying to the terrain. This offer did not find a response from the leadership. However, after the United States in 1975 began the development of strategic cruise missiles (Cruise Missile), the leaders remembered it. Work on the X-90 hypersonic missile was launched in 1976. Developers missiles were ordered to start development completed in the middle of 1976. It was the middle of 1982. By December 31, 1983 a rocket was supposed to adopt. One of the main requirements was that, to ensure that the missile supersonic speed. By the end of the 1970s the new missile was able to reach speeds of Mach 2.5-3.0, and by the end of the 1980s, this value reached Mach 3 to 4. Currently, experts are working on a speed of Mach 7. The initial length of the rocket reached 12 m, later it was reduced to 8 meters. As the carrier hypersonic X-90 acts as a strategic bomber Tu-160M . According to the data, which are known, the missile is 3500 km. The missile carried two warheads independently guided to hit two targets 100 km apart. The letters BL in its American designation refer to the firing range in Barnaul, where it was tested; its Russian industrial index designation is not known.
By one account, in early 1997 engineers from the Raduga Design Bureau in Dubna (located just outside Moscow) displayed a new class of airborne vehicle -- the Kh-90 experimental cruise missile -- at the International Aviation Aerospace Salon (MAKS) in Zhukovsky. In the West, it was called the AS-19 Koala. This rocket was made to replace the Kh-55 strategic cruise missile that is carried by the Tu-160 bomber. Its flight range was 3,000 km. The missile could carry two warheads with individual guidance, each capable of hitting targets at a distance of 100 km from the point of separation. The carrier of the X-90 was to be a modernised version of the Tu-160M strategic bomber. However, according to official data, work on the missile was suspended in 1992.
A successful test of the X-90 was carried out in February 2004, during the strategic command and staff exercises "Security 2004" in the presence of Vladimir Putin. Experimental sample X-90 was successfully tested, which confirmed its efficiency and combat effectiveness. It is impossible to get detailed information on this rocket, in sharing and reviewing specialized literature. This is not surprising, as until now no one could create a hypersonic machine that could maneuver at such high speed and do not break down. Including the United States. Russia in this regard is the undisputed leader, because in the Soviet Union it was a vital necessity. Russia needed to create such devices, which in the shortest time could be anywhere in the world.
The principle of operation is as follows missiles. At the height of 7 to 20 km, it is separated from the aircraft carrier, after which its wings and tail feathers are put forward. It turns solid booster, and further boosters. Then the rocket moves in a path that allows it to overcome any existing and future missile defense systems. According to witnesses, during the tests Topol ballistic missile in 2001, its head part has behaved in an incredible way. It went beyond the atmosphere, and then "plunged" into it, successfully continuing the flight. Then there were reports that it was a pilot unit, which many identified with the X-90.
The closest to the practical establishment of the winged hypersonic missile in the USSR was the Hypersonic Experimental aircraft (Gael), or X-90, created in the ICD "Rainbow" in the late 1980s. After the collapse of the Soviet Union in 1992, the project was closed. Later the unit Gael was repeatedly shown at the aerospace show MAKS in Zhukovsky. By design, it was a cruise missile with a pull-delta wing and fuselage is almost entirely given over to the ramjet engine. With a starting weight of 15 tons of missile Kh-90, as claimed by its developers, can accelerate to a speed of M = 4.5 - this is the minimum value of the hypersonic. According to reliable, but not officially confirmed data, the X-90 rocket at the end of 1980 successfully admitted to the aircraft carrier, and it reached the rated speed. Nevertheless, in the future, this project did not finance itself and subject hypersonic closed for more than 10 years.
In October 2016 Russian defense analyst Vladimir Tuchkov noted that "in the 1970s, the Raduga Design Bureau, now a part of KTRV, began research exploring the possibility of creating a cruise missile with a speed of Mach 5 or greater. At the time, the problem was little studied. Firstly, it was impossible to use ordinary turbojet engines for speeds in excess of Mach 3. The sharp increase in air speed pressure resulted in a loss of efficiency in the engines, with a sharp rise in temperature in the combustion chamber of the air-fuel mixture also reducing efficiency. The higher the temperature, the lower the thrust. Moreover, as temperatures rose, so too did the risk of the rocket's turbine blades becoming deformed and simply melting."
"In this situation," Tuchkov noted, "the only option is the use of a ramjet engine — in this case a hypersonic scramjet. The use of a rocket engine, either liquid or solid fueled, for cruise missiles, is impossible, since the entire trajectory of the flight must be actively controlled and adjustable."
"The design of the scramjet is very simple, with the number of moving parts reduced to a minimum. Theoretically, these craft can reach speeds of up to Mach 25, although the practical ceiling of operation is about Mach 17-19. However, the scramjet also has a significant drawback – its normal operation begins at speeds exceeding Mach 3. Before this speed, it is necessary to accelerate the missile using a solid booster, or some other method, similar to the kind used to launch a high-speed aircraft."
The analyst recalled that when development of hypersonic missile technology first began in the Soviet period, one of the key problems for engineers was overheating. "It was necessary to create the kind of heat shield through which the onboard flight control equipment would continue to work flawlessly." In the 1980s, Raduga Design Bureau created several prototypes of a new cruise missile – the Kh-90, NATO codenamed Koala. The cruise missile weighed 15 tons, had a length of 9 meters, and a 7 meter wingspan. With an expected range of up to 3,000 km, the missile had a design speed of Mach 5.
"The project," Tuchkov noted, "advanced far enough for several test launches to be conducted. During the last of them, the missile reached speeds ranging from Mach 3 to Mach 4." The missile was aircraft-launched. Of course, "all of the USSR's hypersonic weapons designs were strictly classified. It was only due to the fact that the project was closed in 1992 thanks to a lack of financing and the collapse of the defense industry in general that some information about the Kh-90 has become publically available."
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