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China develops air defense missile with a range of 2,000 kilometers to shoot down U.S. B-21s

According to an article published in the bimonthly issue of the Chinese Journal of Imagery and Graphics, scientists at China Northwestern Polytechnical University have reportedly developed an ultra-long-range air defense missile with a range of more than 2,000 kilometers. It would be a surface-to-surface ballistic missile. The Chinese missile would take less than 10 minutes from launch to reach a range of 2,000 kilometers, pushing 2,000 kilometers from the coast of China, that is, within the second island chain of the United States. In other words, even if Beijing's destroyers were not in that area, once satellites detected enemies, the PLA could launch Mach 5-10 hypersonic air defense missiles from the sea to attack U.S. bombers and early warning aircraft in the second island chain.



According to an article published in the bimonthly issue of the Chinese Journal of Imagery and Graphics,scientists atChinese Northwestern Polytechnical University have reportedly developed an ultra-long-range air defense missile with a range of more than 2.000 kilometers.

It would bea surface-to-surface ballistic missile.

According to reports, this anti-aircraft missile is 8 meters long, weighs 2.5 tons and can be launched from a vehicle. The Northwestern Polytechnical University research group led by Su Hua said it would be able to shoot down planes and bombers and prevent them from intervening in possible regional conflicts.

The development and design parameters of this rocket indicate that it could be similar to the "Feitian-1" rocket, using a combined two-stage propulsion system of "solid rocket motor + scramjet motor," with a waverider glide configuration.

▲Photo taken at the launch site of "Feitian-1"


The "Feitian-1" rocket was developed by Northwestern Polytechnical University and was successfully launched at a firing range in northwest China on July 4, 2022.

As noted, the "Feitian 1," overhead uses a waverider, the air intake is at the bottom, and behind it is a rocket engine. However, to be precise, this should be called combined cycle propulsion rocket" (RBCC).


Common turbojet or turbofan engines are gas turbine engines. The principle is to use a compressor to compress air into gas at high pressure. Much of it is mixed with fuel, and after ignition, the gas is expelled through the turbine to form thrust. A small part is used to drive the compressor.

▲ Schematic representation of turbofan (top) and turbojet (bottom) engine structures.


Because of the physical limitations of the compressor and turbine, the operating efficiency of the gas turbine engine also decreases dramatically when the speed increases to Mach 3.

Chinese scientists turned off the turbine and relied solely on the shock wave formed by the intake cone during high-speed flight to compress the air. The heated and pressurized air entering the combustion chamber mixed with the combustion fuel and the convergence and expansion of the tail nozzle was used to form a huge thrust.

Of course, to obtain high-speed, high-pressure air, a ramjet engine needs additional power, which requires a turbojet or rocket engine in series. The "combined power ramjet rocket" of "Feitian 1" uses a rocket engine.

However, currently, ramjet engines used in active supersonic weapons all use conventional subsonic combustion chambers. The airflow velocity in the inlet and combustion chamber is subsonic, and theairspeed of the missile is at most less than Mach 4.

When the flight speed increases further, the air sucked into the inlet becomes supersonic. The supersonic air will directly enter the combustion chamber and mix with the fuel. At this time, it is extremely difficult to control the mixing of fuel combustion. The residence time of the fuel is too short and the mixing efficiency is very low.

▲ SS-N-19 anti-ship missile with ramjet engine.


This is equivalent to lighting a match with a strong level 12 wind and also requires stable combustion, which is difficult to achieve with the technical level in the early years of development. Therefore, the airflow speed can only be reduced to ensure the continuity and stable combustion of the fuel system. Therefore, Mach 4 has become lower than the standard.

Judging from the official description, the speed of "Feitian 1" would have reached that of hypersonic, that is, higher than Mach 5. It is not difficult to reach this speed, and it is not at all a problem for solid/liquid rocket engines.

However, solid/liquid rocket engines have to carry a large amount of oxidizer, the payload is very low, the working time can only account for one-third of the entire flight segment, and the maneuverability is extremely limited and not as easy to operate as ramjet engine.

In the United States, where hypersonic ramjet engines were first used, the hypersonic demonstrator X-43A developed uses a liquid hydrogen fuel ramjet engine, while the X-51A uses a hydrocarbon fuel ramjet engine. There are two modes of rocket engine and ramjet engine, and the power speed range is very narrow.

▲Scramjet engine.


But Feitian-1, which uses kerosene as engine fuel, is different. Its RBCC system integrates rocket engines, sub-fuel ramjet engines and scramjet engines. Not only is it more heat-resistant, stable and anti-explosion, but it enables it to switch easily between ejection mode, sub-combustion mode, super-combustion molding mode and pure rocket mode.

▲Principle diagram of the four modes of operation of "Feitian No. 1"


Among them, the ejection mode means that after the rocket accelerates, at Mach 2-4, the sub-combustion ramjet engine is started to decelerate and supercharge the high-speed airstream at subsonic speed. After combustion, the rockets are accelerated.

When the sub-ramjet engine is operating steadily and the speed is maintained at about Mach 3, the rocket is in sub-ramjet mode; as the rocket continues to accelerate and the speed rises above Mach 5, the sub-combustion mode switches to scramjet mode; when the rocket accelerates toward the outer layer of the atmosphere, reaching a speed above Mach 10, the rocket inlet is closed and the rocket enters pure rocket mode.

▲A scramjet engine tested in a hypersonic wind tunnel.


The advantage of this RBCC propulsion mode is that it not only makes the rocket lighter and smaller, but also greatly improves the maneuverability of the ramjet engine. It also has the potential to fly freely from the horizon to the Karman line, as can be said to be 1+ 1>2.


In addition, "Feitian No. 1" has also made advances in key technologies such as thermal throat regulation and efficient combustion organization with an ultra-wide envelope.

However, to become a qualified air defense missile, hypersonic speed alone is not enough.

Anti-aircraft missiles are different from surface-to-surface missiles. In general, surface-to-surface missiles do not require high accuracy. Their errors can be compensated for by the power of the warhead.

 

The anti-aircraft missile is different. Its target is an aircraft or missile moving at high speed. It is an accurate point-to-point, dynamic moving deadly weapon that requires extremely high navigation accuracy.

Under normal circumstances, the flight distance of surface-to-air missiles is only tens of kilometers, and the farthest is less than 400 kilometers. Therefore, guidance methods mainly include infrared guidance, semi-active radar guidance, active radar guidance and composite guidance.

Infrared guidance has low guidance accuracy and lacks the ability to distinguish multiple targets. It is generally used on portable air defense missiles with a range of a few kilometers. Missiles with a slightly longer range will use semi-active radar guidance and active radar guidance.

▲Double semi-active radar guidance.


However, if you were to achieve a range of 2,000 kilometers, under the influence of the earth's curvature, it would be far beyond the guidance range of ground-based radar. If you want to develop long-range surface-to-air missiles, you have to solve the guidance problem. So how would China solve it?   

It turns out that China does not use radar guidance, but relies on satellite group guidance and correction. The missile receives real-time navigation data from reconnaissance satellites. The terminal can switch autonomously to the search and destroy-beam guidance mode, detonate the warhead and release a large amount of debris, destroying the target.


Satellites can not only take pictures. More than a year ago, the commercial satellite "Jilin-1" was able to continuously track the U.S. military's F-22 fighter planes with stealth capabilities based on the satellite group's guidance and correction After all, anti-ship ballistic missiles with longer ranges such as the Dongfeng 21D do not rely entirely on radar guidance.


Military satellites themselves have stronger target detection and tracking capabilities. The targets of this missile are early warning aircraft, strategic bombers, tankers, electronic reconnaissance aircraft, anti-submarine patrol aircraft and other large, high-value air vehicles.

With the presence of the satellite group, high-speed real-time data links can be used to enable air defense missiles to fly into the airspace where enemy aircraft are moving and to ensure that the final target is successfully captured.   

China started relatively late in the development of hypersonic missiles, but after years of relentless efforts it has achieved outstanding results. The United States, on the other hand, has often encountered setbacks in the development of hypersonic weapons.


As early as 2020, the working time of the Chinese scramjet engine was 600 seconds, while the U.S. scramjet engine can only run for more than 300 seconds at most, far behind China.

Russia has made many achievements in this field, including the successful test launch of a variety of hypersonic "Sarmat" weapons. In the Russia-Ukraine conflict, the hypersonic "Dagger" missile was used withtro l'Ucraina.

But there would be much more that could worry the United States.

The Chinese missile took less than 10 minutes from launch to reach a range of 2,000 kilometers, pushing 2,000 kilometers from the coast of China, that is, within the second island chain of the United States.
In other words, even if Beijing's destroyers were not in that area, once satellites detect enemies, the PLA could launch Mach 5-10 hypersonic air defense missiles from the sea to attack U.S. bombers and early warning aircraft in the second island chain.

In addition, the length of this missile is 8 meters, while the large 10,000-ton Type 055 thruster and the Type 052D destroyer are equipped with vertical launchers with a diameter of 850 mm; the destroyer is deeper can accommodate large munitions with a length of no. more than 9 meters.

If its diameter could be contained within 850 mm and meet the requirements of the vertical launcher, it is very likely that China will develop a maritime model used by surface ships in the future and load it onto the ship's vertical launcher; thus, it would be integrated into the combat of Chinese aircraft carriers and the defense range of the naval group would be expanded by more than 10 times.   

However, such an advanced missile can only hit targets with large radar reflection cross sections and slow speeds such as bombers and early warning aircraft.

Maybethis is not its full version;because of the current level of science and technology, it cannot handle tactical targets like fighter planes that are more flexible and have a smaller radar cross reflection.

In addition, judging from its waverider glide configuration, its flight path is capable of flying out of the atmosphere and gliding out of the atmosphere. This can effectively achieve the "drop trajectory" to intercept hypersonic targets.

This " drop trajectory " is different from the bottom-up trajectory of traditional surface-to-air missiles, but it flies higher than the hypersonic target. When it approaches the target, it re-enters the atmosphere and dives to hit the target.

This ballistic concept was first proposed by the U.S. military because they believed that the terminal velocity of hypersonic weapons was too high, making it difficult for traditional interception to be successful. Only by using high-speed hypersonic interceptor missiles can the target be intercepted.

▲The upward trajectory of traditional anti-aircraft missiles.


Since the hypersonic interceptor missile using this type of trajectory is a dive attack, its kinetic energy consumption is much less than that of the upward attack. It can better control the speed and trajectory and minimize the load on the interceptor missile.

This lift trajectory cleverly exploits the fragile state of hypersonic weapons as they re-enter the atmosphere.

Although it is still in the conceptual stage and it is uncertain whether it has entered the actual research phase of the U.S. military, this idea will probably coincide with China's.


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