Over Baghdad, Iraq, in 1991
A U.S. Air Force F111 fighter-bomber is preparing to bomb an important military target in Baghdad.
Prior to this, various fighters of the U.S. Air Force had taken turns bombing this target many times.
(F111 Aygu fighter-bomber)
Until now, however, the U.S. Air Force has not destroyed this target. This hard bone is the underground command post of the Iraqi army in Baghdad.
This command post is located tens of meters underground, and all kinds of precision-guided weapons of the US military are feathered in front of the tens of meters thick soil level.
However, F111 pilots were confident in their operation, because two brand new bombs were on their planes.
This precision-guided bomb, called GBU-28, is a new type of bomb just developed by the United States not long ago.
(GBU-28 "Jewel Road III" laser-guided bomb)
In order to complete the development as soon as possible, the GBU-28 directly used the barrel of the 203 mm howitzer in the US military stock as the projectile body, and the workers filled the gun barrel directly into the gun barrel in the open space.
After arriving at the intended bombing point, the F111 pilot pressed the bomb launch button and two improvised "simple bombs" were dropped from the magazine.
Guided by laser illumination provided by other fighter jets, the GBU-28 flew accurately towards the target.
With a loud explosion, GBU-28 pierced through tens of meters of soil, completely destroying the underground command post in Baghdad.
(GBU-28 laser-guided bomb about to land)
The first time the ground drill appeared in front of the eyes of the world, it showed its great power.
The U.S. military continues to develop ground drills
In the 1991 Gulf War, the US military used ground drilling shells for the first time in actual combat, achieving great success.
The U.S. military, which had tasted the sweetness, immediately began the follow-up research and development of ground drill bombs, first of all, to improve the GBU-28 with obvious emergency colors.
The U.S. military replaced the GBU-28 with a new warhead and fuze, so that the GBU-28 can be detonated after drilling into a certain depth underground, strengthening the ability to drill the ground.
This improved version was designated the GBU-37 by the U.S. Military and subsequently equipped with the U.S. Air Force.
(F-15 fighter jet drops GBU-28 laser-guided bombs)
American ground drill bombs are dropped at an altitude of 10,000 meters through fighters or bombers, and use gravity to accelerate to obtain a high speed, thereby obtaining huge kinetic energy and achieving the purpose of drilling the ground.
According to the velocity-displacement formula in the acceleration formula, how much velocity the drill can obtain depends on how high the drill bullet is launched.
(Velocity-Displacement Formula)
However, the speed that the ground drill can obtain is not infinitely increased, because the flight altitude of the aircraft is limited.
For jets, an altitude of 20,000 meters is basically the upper limit of the flight altitude of most jets, as are fighters that drop ground-penetrating bombs.
Therefore, for the ground drill bomb, there is no way to continue to improve the landing speed, so how to continue to improve the ability to drill the ground?
According to the kinetic energy formula, at a certain speed, increasing the mass of the object can obtain greater kinetic energy.
(GBU-57 Ground Drill)
So the U.S. military's latest GBU-57 ground drill bomb weighs a staggering 14 tons. The sheer mass allows the GBU-57 to drill through 60 meters of reinforced concrete, the strongest ground-penetrating bullet available.
In addition to the huge GBU-57 ground-penetrating bomb, the U.S. military has also improved the small SDB-guided bomb with a sturdy ground-penetrating warhead.
The improved SDB guided bomb is less than two hundred kilograms, but it can penetrate 1.3 meters of reinforced concrete.
(SDB guided bomb that penetrated the concrete machine fort)
The US military tried every means to improve the drilling capability of the ground drill bombs, and the threat was menacing. So, how do we deal with the US military's ground-penetrating bombs?
In fact, we have many different coping methods, and the author proposes three strategies here.
The next step - a stronger shield to block all attacks
In the face of increasingly strong drilling bombs, the easiest way to think of is to strengthen underground bunkers. As long as the underground bunker is strong enough, "the drill bomb will not be able to defeat the underground bunker."
However, how to strengthen underground bunkers is a profound science, and countries have also studied it for decades. Here are some examples of some of the more common reinforcement methods.
The first is the use of special concrete with better mechanical properties. Ordinary cement is easy to crack and break in the face of severe impact because of its general mechanical properties.
The drill projectile takes advantage of this, penetrating the concrete through violent impacts.
(Reinforced concrete is the most common bunker material)
However, special concrete with special formulations improves the mechanical properties and becomes "elastic", greatly reducing the degree of cracking and breaking in the face of impact.
According to the U.S. military's own tests, the GBU-57, which can penetrate 60 meters of ordinary concrete, can only penetrate 8 meters when facing special concrete.
In addition to the use of special concrete, it is also possible to resist drilling bullets through specially designed protective structures.
A special structure is a composite protective structure, similar to the composite armor of a tank.
Its structure is characterized by a protective layer composed of several different materials from top to bottom, some of which are hard, some are relatively soft, and some are full of elasticity.
(How the composite armor of the tank works)
Its working principle is that when the high-speed moving ground drilling projectile passes through different protective layers with different degrees of softness and hardness of the material, the force generated by each layer of material on the projectile body is different because of the different materials.
Because the force of the projectile in different material layers is not the same, the body of the drill projectile will be subjected to different forces of different directions and sizes at the same time.
Under the pull of these forces, the body of the drill bomb is easily deformed or even destroyed.
The ground drill shell that lost its original shape also lost the ability to drill the ground and could not continue to penetrate the protective layer.
Another special structure is a multi-layer inclined steel plate, which is a reference to the inclined armor of the tank.
(Many tanks use tilted armor to improve protection)
When the drilling bullet comes into contact with the inclined steel plate, because the speed of the drilling bullet is not very high, and the diameter is relatively large, it will bounce on the inclined steel plate like the old-fashioned full-caliber armor-piercing bullet.
Even if the drill bomb can "smash" through the top steel plate with huge kinetic energy, there is a second and third channel at the bottom... Ground-penetrating projectiles whose speed is greatly weakened by the first layer of steel plates are difficult to penetrate all the steel plates behind them.
By weakening several layers of steel plates, it is possible to make the drill bomb lose the ability to drill the ground before it reaches the bunker.
Finally, there is a simple and crude but effective method, that is, to greatly deepen the depth of the bunker, as long as the depth exceeds the drilling ability of the drill bomb, it can make the drill bomb unable to attack the bunker.
For example, our country has some important military facilities built in the middle of the mountains, and the top is a thick mountain.
CCTV once reported an underground bunker that had been deactivated, reaching a depth of 500 meters.
(Built in an underground bunker deep in the mountains)
It should be known that even the GBU-57 of the US military has only 200 meters of drilling ability in the face of such a soft land as a mountain, and can only be helpless in the face of such a bunker with a depth of 500 meters.
However, regardless of the above means of reinforcing bunkers, without exception, they all need to face huge engineering and construction challenges, which are very costly, and only a small number of vital bunkers will use these means.
Therefore, in the face of ground drilling bombs, the method of passive resistance by reinforcing bunkers can only be regarded as a downward strategy.
Middle strategy - as long as the drill bomb is stopped, the bunker is safe
Since the ground drill bomb is a huge threat to the bunker, let's change our thinking, if the ground drill bomb is solved, then our bunker will not have to worry about the blow of the ground drill bomb?
This is another way to deal with ground-penetrating bombs - intercepting ground-penetrating bombs.
As mentioned earlier, the American ground drill bomb is dropped at a high altitude by a carrier aircraft, so that the ground drill bomb accelerates under the action of gravity and obtains kinetic energy to achieve the ability to drill the ground.
(B52 bombers dropping GBU-57s)
How much speed can the drill projectile get?
Excluding the air resistance factor, it is assumed that the drill projectile is launched at an altitude of 20,000 meters, and calculated according to the velocity-displacement formula (the mass size does not affect the acceleration and final velocity).
As a result, the ground-penetrating bomb dropped from a height of 20,000 meters reached a speed of about 630 M/S when it reached the ground, less than twice the speed of sound.
Ground drill projectiles like the GBU-57 are quite large and are easily locked by the radar of the air defense system.
(Hongqi 9 air defense missile system)
For modern air defense systems, intercepting a target twice the speed of sound is not a very difficult task.
Modern fighter jets fly more than twice the speed of sound abound, and various supersonic air-to-surface missiles, such as the US military's Hamm anti-radiation missile, generally fly at two to three times the speed of sound.
Therefore, the deployment of modern air defense systems near bunkers will enable ground drills to intercept ground penetrating shells. However, not all anti-aircraft missiles can effectively intercept ground drills.
In order to be able to successfully drill into the ground, the ground drill bomb has a solid shell, and the general anti-aircraft missile warhead cannot move the shell of the ground drill bomb, and it is even difficult to affect the flight trajectory of the ground drill bomb.
(Hongqi 9 foreign trade version FD2000 missile warhead)
However, our country has an anti-aircraft missile that can be competent for the interception task of ground drilling bombs, that is, the Hongqi 9 air defense missile.
This is because the Hongqi 9 anti-aircraft missile has a warhead weighing up to 64 kg, which is full of power and is fully capable of effectively killing strong ground-penetrating projectiles.
The cost of deploying an air defense system is much lower than that of fortified bunkers.
However, the use of anti-aircraft missiles to intercept the falling ground-penetrating bombs is more dangerous, and in case of mistakes, the bunker will be attacked, and the overall situation is more passive.
Therefore, we have another good strategy for dealing with ground-penetrating bombs.
The best strategy - to solve the aircraft that drops ground bombs, there is no problem of ground bombs
As we mentioned earlier, when the American ground drill bomb is used, it is used by bombers or fighter jets to fly over the target and drop the ground drill bomb to strike.
So we can solve the problem of ground drill bombs in other ways, for example, if the plane with the ground drill bomb is shot down, is it not necessary to consider how the bunker resists the ground drill bomb problem?
(B2 launch GBU-57)
In fact, this is also true. The most efficient way to deal with bombing by a bomber is to shoot the bomber down before it can be dropped.
And American ground drill bombs have a characteristic, that is, they are particularly heavy.
Bombs weighing more than a dozen tons like the GBU-57 are too big and too heavy to add glide extended components, beyond the bomber's mounting capacity.
Therefore, the US military's ground-penetrating bombs need to be dropped by bombers in the air to be used normally. In order to be able to successfully break through the interception of air defense systems, the US military was carried by B2 bombers with GBU-57s.
(GBU-57 hanging in the B2 bomb bay)
The B2 bomber is the only stealth strategic bomber currently in service, and its radar reflection cross-section is small, which puts high demands on the detection of air defense systems.
However, thanks to the efforts of Chinese military researchers, China's anti-stealth technology has made great progress.
Since the birth of stealth aircraft, major military powers have increased their investment in the research of anti-stealth technology. The United States, Russia, and France have all conducted many studies on the use of mipo radar in anti-stealth technology.
(Russian three-coordinate meter-wave radar)
The radar wavelength of the meter wave radar is several meters to tens of meters, while the stealth aircraft can only be invisible to the radar wave of the centimeter level.
It can be said that the Mipo radar is a natural enemy of stealth aircraft by nature.
However, the meter-wave radar also has many disadvantages, the first is that the traditional meter-wave radar is only a two-coordinate radar, and it takes three coordinate values to determine the position of the target.
The second is that the wavelength of the meter-wave radar is too long, resulting in the low accuracy of the traditional meter-wave radar detection.
Russia and France have done a lot of research on these problems and developed a three-coordinate radar that can measure the three coordinate values of the target.
China has gone further in the research of new meter-wave radars, introducing a three-coordinate meter-wave anti-stealth radar with a phased array system.
(China's anti-stealth mibo radar on display at the Zhuhai Airshow)
On the basis of the development of three-coordinate meter-wave radar, China uses a phased array radar system and combines a new background algorithm to solve the worldwide problem of low accuracy of meter-wave radar detection.
For a long time, the meter wave radar can only be used as a warning radar because of its low accuracy.
China's new mibo anti-stealth radar has a relatively high detection accuracy, which can be used as a fire control radar to directly guide anti-aircraft missiles to attack stealth aircraft.
In addition to guiding anti-aircraft missiles to intercept stealth bombers such as B2, China's new Mibo anti-stealth radar can also transmit target information to fighters patrolling the sky through data links.
(Chinese Air Force fighter carrying air-to-air missiles)
After receiving the target information, the fighter can approach the target to intercept.
Intercepting a bomber in flight is much easier than intercepting a falling ground-penetrating bomb, and the cost is not high, which can be said to be the best way to deal with a ground-penetrating bomb.
It can be seen that although the ground drill bomb is very powerful, there are many ways to deal with it.
Everything is mutually exclusive, and every powerful weapon can find a corresponding way to deal with it, so there is no "omnipotent" weapon in this world.