Author: Rong ping source: official account: Rong Ping (ID: rongping898) has been authorized to reprint
The vicious incident of the National Security Bureau, a US government agency, launching a cyber attack on China’s northwest Polytechnic University shocked the world. Although it is not clear what the US conspiracy is so far, everyone coincidentally remembers what happened two months ago.
According to the official wechat report of Northwestern Polytechnic University, on July 4, 2022, the feitian-1 rocket ramjet combined power developed under the leadership of the aerospace combined power team of the College of Astronautics of Northwestern Polytechnic University was successfully launched, which verified the multi-modal smooth transition and wide-range comprehensive ability of kerosene fueled rocket ramjet combined cycle engine for the first time in the world, breaking through the thermal throat regulation Key technologies such as ultra wide envelope and high-efficiency combustion organization were successfully tested in flight.
Key points: rocket ramjet combined cycle engine! This belongs to one of the three technical routes of scramjet, namely RBCC Rocket + scramjet, and the other two are trre of turbine + Rocket + scramjet and TBBC of turbine + scramjet.
The feitian-1 scramjet of Northwestern Polytechnical University has a wide range of applications, but in countries with in-depth research in this area, it is mainly used for the research and development of new hypersonic weapons.
According to the different flight dynamics, hypersonic weapons are divided into two categories, one is hypersonic glide missile HGV with rocket engine as the driving core, and the other is hypersonic cruise missile HCM with scramjet engine as the driving core.
Of course, the strategic significance given by the two is completely different. If it is said that HGV has the possibility that the global anti missile system built by the United States after spending several trillion dollars for more than half a century will become the Maginot line of defense in the new era, then HCM makes this possibility a 100% reality!
In the middle and late cold war, in the face of the Soviet Union’s powerful intercontinental ballistic missile group, the US aerospace system made the same mistake as France. At that time, France tried to solve the German land-based threat once and for all by building the Maginot defense line on the French German border, which is known as the most powerful defense in human history. The United States also tried to solve the Soviet missile threat once and for all by building a multi-gradient anti missile defense network on the sea, land, air and space.
But facts have proved that there has never been any impregnable shield.
The German army can take the Ardennes heights to bypass the Maginot Line and surprise France. China and Russia can also develop new missile technology to bypass the anti missile version of the Maginot Line and surprise the United States. The hypersonic missile is a new technology that bypasses the anti missile version of the Maginot defense line.
The current Anti Ballistic Missile System of the United States is based on Anti Ballistic missiles. The Anti Ballistic Missile air defense system can be divided into three stages according to the flight area of the ballistic missile: the booster Anti Ballistic Missile when the missile just takes off from the enemy country’s mainland, the mid-range Anti Ballistic Missile when the warhead flies out of the atmosphere, and the terminal Anti Ballistic Missile after the warhead re enters the atmosphere until it hits the ground and explodes.
Theoretically, booster antimissile is the easiest stage to achieve and the stage with the lowest loss rate. First, when the missile just takes off from the mainland, the rocket engine is in the stage of full speed operation. At this time, the infrared characteristics produced by the engine’s tail flame under high temperature combustion are extremely obvious. The strategic pre guard star floating in space can find it at a glance, which is very conducive to detection and tracking; Second, in the booster phase, the missile is still flying in the atmosphere, and the strong friction and ascending resistance make the speed of the missile much lower than that outside the atmosphere, so the probability of successful interception is extremely high; Third, because the booster anti missile is carried out over the enemy country, most of the missile fragments and radioactive substances fall on the spot, which has little impact on the target country.
However, the missile range and speed of anti ballistic missiles are far lower than those of ballistic missiles, which means that if we want to achieve the Anti Ballistic Missile in the booster stage, we must link the anti ballistic missile position at the door of the enemy country!
A few years ago, the United States deployed the THAAD ABM system in South Korea precisely because it wanted to shoot down the missiles of China and Russia in the boost phase, which not only abolished more than half of the strategic strike capability of the two countries, but also did not have to bear the risk of falling objects in their own countries. However, due to the tough Countermeasures of China and Russia, the THAAD system that actually landed in South Korea was relatively limited, which could not form a constraint.
Although the mid course antimissile intercepted outside the atmosphere and the terminal antimissile intercepted above the country are not as ideal as the booster antimissile, in particular, the terminal antimissile still has the risk of causing great damage to the country by falling objects and radioactive substances.
But on the one hand, after the traditional ballistic missile leaves the atmosphere, the rocket and the warhead will automatically separate. At this time, the warhead has no power source and can only fly according to a fixed parabola. Modern advanced computers can accurately analyze the flight trajectory and target of the warhead in a very short time, and then calmly organize interception.
On the other hand, because of the extremely high moving altitude of ballistic missiles, it is impossible to make full use of the favorable factors of the curvature of the earth to reduce the exposure rate. Therefore, when the space-based strategic early warning satellite can not track the infrared signal of the warhead, the radar deployed on the sea surface and the ground can immediately take over the tracking, reduce the reconnaissance blank period, and basically achieve the whole process detection and tracking.
It needs to be particularly emphasized that although the major ballistic missile powers have developed warheads capable of terminal activation and orbit change in recent years, since their trajectories are fixed and discovered in the middle, the range of terminal orbit change is very limited, so they can still be intercepted effectively.
In the 1980’s, the United States announced the technology of terminal trajectory change of ballistic missiles. It can be clearly seen from the figure that even if the trajectory can be changed, the range is very small. That is to say, the contemporary anti missile system is based on the full range tracking and trajectory fixation of the infrared characteristics of warheads by space-based strategic early warning satellites and sea based and land-based radars. The technical route of hypersonic glide missiles has overthrown all these key points.
The following figure shows the trajectory of several missiles.
Light blue is the trajectory of traditional ballistic missiles, purple is the trajectory of mobile reentry vehicles, yellow is the trajectory of in orbit bombing systems, red is the trajectory of hypersonic glide missiles, and green is the trajectory of hypersonic cruise missiles. Here, we will focus on the trajectory of HGV hypersonic glide missiles.
First of all, the power source of HGV is the rocket engine. The infrared characteristics generated by the tail flame during launch can naturally be detected by the space-based strategic early warning satellite. The key point is that HGV did not fly to the middle of the traditional ballistic missile and separated from the rocket. At this time, the infrared characteristics generated by the warhead’s own friction with the air are much lower than the tail flame of the rocket engine. It is difficult for the strategic missile early warning satellite to continue reconnaissance.
What about the radar deployed on the ground and sea?
It can be found, but the flight altitude of hypersonic glide missiles is between 40 and 100km, which is closer to the ground than ballistic missiles, which needs to consider the influence of earth curvature. As we all know, the earth is a spherical body, and its surface is arcuate rather than straight, but the electromagnetic wave emitted by the radar propagates in a straight line. Therefore, when the wave band crosses the straight line and enters the arc range, it can not be detected. Only when the target enters the straight line of view can it be detected.
HGV flies close to the earth’s surface from the perspective of space,
HGV flies at an altitude far lower than the ballistic missile, making full use of the favorable factors of the earth’s curvature and greatly shortening the enemy’s reconnaissance window. Strategic antimissile time is as important as technology. Under the same technical conditions, the later the time of discovery, the higher the probability of interception failure.
Secondly, the flight trajectory cannot be predicted. The following figure is a comparison of the trajectory of traditional ballistic missiles and HGV. The blue line is the traditional ballistic missiles, and the trajectory is a fixed parabola; Yellow is the trajectory of the HGV. We can clearly see the range of the warhead’s lateral movement in the atmosphere. It is tens of kilometers near and hundreds of kilometers far. The trajectory is erratic
Certainly, the traditional antimissile means of intercepting a fixed trajectory can not be grasped at all.
As mentioned above, there is no impregnable shield and no unstoppable spear in the world.
Hypersonic glide missiles are only extremely difficult to intercept, which does not mean that they will not be able to intercept them. At least the Americans in the United States think so. In 2019, George nakuzi, a senior engineer of RAND Corporation, pointed out in an article that the hypersonic glide missile lost its power source after it separated from the rocket. Every time it made a maneuver in the atmosphere, its speed would decrease a lot. By the time it hit the target, its speed had been lost by two thirds. This means that the closer the warhead is to the target, the smaller the number and intensity of maneuvers, which greatly increases the possibility of trajectory prediction, Therefore, the US active ABM system has the opportunity to intercept, and the focus is on early warning and tracking.
To this end, George nakuzi proposed two countermeasures: first, build a dense space surveillance network. Satellites that look down on the earth from top to bottom have incomparable advantages in reconnaissance. However, the position of strategic early warning satellites is too high, ranging from thousands of kilometers to tens of thousands of kilometers. They have more than enough heart and less strength for vehicles with less obvious infrared characteristics.
In this case, a group of medium orbit satellites with an altitude of 1000 kilometers to 300 kilometers should be used, and a large number of sensors should be installed on them to enhance their sensing ability, so as to build a space-based monitoring network without dead corners. This solution requires the United States to deploy a dense satellite group in mid orbit, but it is not a big problem. SpaceX’s satellite alliance is fully competent.
Second, build a ghost fleet. Although the influence of the curvature of the earth on radar reconnaissance cannot be changed, as long as enough reconnaissance equipment is scattered on the ocean and every direct view plane always maintains the presence of radar, it can achieve monitoring without dead corners.
In order to achieve the effect of restraining the curvature of the earth by quantity, the demand for warships will not be small. The cost of traditional manned warships is too high, and it is not suitable for long-term deployment. Intelligent unmanned warships are the only choice. The Pentagon pointed out in this year’s Navy plan that by 2045, the US military will have at least 100 large unmanned warships in the Pacific.
At the beginning of this year, the US Marine Corps received the metal shark long-range unmanned ship and established the unmanned ship formation integration command
It may be feasible to use dense swarm tactics to defend HGV with declining kinetic energy, but if it comes from hypersonic cruise missile HCM, the United States will have no choice at all.
The rocket engine that provides the main kinetic energy for HGV has another disadvantage besides the disadvantage that the infrared characteristics generated by the tail flame are easy to capture: it needs to carry more than ten times more oxidants than fuel to fully burn in the air, which not only increases the load, but also lacks more power.
HCM with scramjet can take off in many ways, either by rocket or by its own kinetic energy, which greatly reduces the probability of being detected at takeoff.
The scramjet, which can constantly absorb oxygen from the air and convert it into kinetic energy, on the one hand reduces the volume of the aircraft because it does not need to carry oxidants. The smaller the volume, the less infrared features will naturally be generated after friction with the air. Theoretically, the TBBC type hypersonic cruise missile using the combination of turbine and scramjet can not be detected by existing and known satellite technologies.
on the other hand,
The raw material of the scramjet is inexhaustible oxygen in the air, which makes the HCM capable of all kinds of high-intensity maneuvers while maintaining high speed throughout the whole process. Even if the enemy’s reconnaissance system is lucky to find its trajectory, it does not have effective interception means. After all, there is no fixed trajectory and target judgment.
More importantly, HCM is small in size and has no fixed launch site. It can be launched by aircraft, warships, traditional missile launch vehicles and even submarines.
But more advanced technology often represents a higher R & D threshold.
The scramjet is not complicated in structure, and the difficulty lies in the intake heat treatment. Common jet engines are compression ignition ramjets. When air enters the engine, it first becomes subsonic, and then ejects at supersonic speed after burning with fuel. The advantage of this is to reduce the wear of the engine caused by extreme high temperature.
All the processes of scramjet from intake to compression to combustion are carried out in supersonic environment. Not only is the combustion extremely unstable, but the ultra-high temperature caused by the friction between the supersonic air flow and the engine during intake can not be withstood by any material before 2020.
Structural diagram of scramjet
It is an indisputable fact that the United States, as the number one aerospace power, has led China in the hypersonic field for a long time. But it is also because it is too strong that the US military’s self-confidence bursts. In their eyes, hypersonic glide missiles propelled by atmospheric lift and rocket engines are not high-tech, but ingenious. If they want to develop the most advanced hypersonic cruise missiles, they will be stuck for decades, More and more difficulties have been encountered.
On the other hand, China has moved from easy to difficult step by step. Now HGV not only tops the world, but also is likely to become the first and only country in the world to solve the three technical routes of HCM.
The scramjet technology can also be applied to aerospace aircraft, which is the key to China’s overtaking in the future and breaking the technical barriers of European and American supersonic airliners in a higher dimension. Today, the gap between the United States and China in the hypersonic field is not much different, but it is not exaggeration to lag behind half an era.
Since the end of World War II, the United States has never met an opponent who completely crushed it in terms of technology that determines the direction of future war. China is the first, so their anxiety can be imagined. Since you can’t figure it out yourself, it’s better to steal it cost effectively and directly. After all, theft is not only the traditional skill of American intelligence agencies, but also the heritage and glory of Americans!
Before, I wondered why the United States scolded China for stealing its technology all day. Now I understand that thieves like to be thieves and shout to be thieves.