Earlier this month, the US State Department approved the arms sales plan to Saudi Arabia and the United Arab Emirates. Among them, Saudi Arabia will purchase 300 “Patriot” missiles at a price of more than US $3 billion to replenish its depleted stocks.
After nearly 40 years, the “Patriot” has developed from a medium – and long-range air defense system to a typical terminal antimissile system – from radar to missiles, from guidance system to killing mechanism. It has been almost completely changed.
“Patriot” has been used in actual combat for many times and is the antimissile system that intercepts the most live missiles. However, can it really play a role when encountering “uncooperative opponents”?
Text | Zhang Xuefeng
Editor | Pu Haiyan lookout think tank
This article is an original article of Wangwang think tank. If you need to reprint it, please indicate the source of Wangwang think tank (zhczyj) and the author’s information before the article. Otherwise, legal liability will be strictly investigated.
Continuous iteration and continuous improvement
“Patriot” is called patriot in English, which is made up of the first and second letters of “phased array tracking to intercept of target”. It is a small tradition for Americans to name the weapon with this “Pun” technique. The number of this system is mim-104. It was originally developed by Raytheon as the main contractor. It is a medium and long-range air defense system. After continuous upgrading, it has the terminal anti missile capability.
On April 11, 2013, patriot PAC-2 missiles were deployed near Seoul, South Korea.
The basic “Patriot” air defense system was first equipped with the army in 1984, with the number of mim-104a. In 1988, the first “Patriot advanced capability” (PAC) upgrade was carried out, mainly the software upgrade, known as PAC-1, or “patriot-1”, with limited tactical ballistic missile interception capability.
Later, in order to further enhance the anti missile capability, the US military upgraded the “Patriot advanced capability” – 2 and further optimized the radar search algorithm. At the same time, the missile itself was improved, the intercepting ballistic missile was optimized, and its fragments were increased from 2 grams to 45 grams, and the fuze was improved.
[Note: fragment, i.e. fragment killing warhead, is one of the main types of warhead. It mainly relies on the explosion of high-energy explosives to form a large number of high-speed fragments, and uses the high-speed impact, ignition and detonation of fragments to damage the target.]
Engagement procedures have also been optimized, with the launch interval between two missiles increased to 3 to 4 seconds, so that the second missile can distinguish ballistic missile warheads after the first missile explodes. PAC-2 was first tested in 1987 and equipped with the army in 1990, just in time for the Shanghai Bay war.
In the 1990s, PAC-2 missile was greatly improved again, and four different improved types were collectively referred to as guidance enhanced missile (GEM). The main upgrade of the gem missile is to replace it with a new and more responsive proximity fuze. The test shows that the fuze on the original PAC-2 missile detonates the warhead too late when it is engaged with the ballistic missile, so it is necessary to shorten the fuze delay. Gem missile has also obtained a new “low noise” high-performance seeker to reduce the interference of missile radar seeker and better detect low radar cross section (RCS) targets. Gem missiles were widely used in the so-called “Iraq freedom” operation that invaded Iraq in 2003.
On the basis of enhanced guidance, gem-t and gem-c missiles are upgraded, “t” represents tactical ballistic missiles and “C” represents cruise missiles. These missiles have been equipped with new guidance heads, which are specially used to more effectively counter low altitude and small reflector targets such as cruise missiles. Gem-t also uses a new fuze, which is further optimized for intercepting ballistic missiles and improves the sensitivity of the seeker to low radar cross-section targets. These two are collectively referred to as gem +, and were equipped in November 2002.
PAC-3 missile has greatly upgraded almost every aspect of the system, from missile to radar to guidance system. The upgrade is divided into three stages: configuration 1, 2 and 3. The PAC-3 we often say refers to the final model. The radar of the system is changed from an / mpq-53 to an / mpq-65, and the missile is also a brand-new model. The conductor system is changed from TVM guidance mode to active radar guidance. The warhead is changed from fragment killing warhead to kinetic energy killing warhead (that is, the incoming missile is directly destroyed by impact). The shape and weight of the missile have been greatly reduced. The space originally equipped with one missile can be equipped with four PAC-3 missiles.
[Note: active radar guidance refers to the radar carried by the missile to transmit signals. It does not need to rely on the assistance of other vehicles, and uses the radar wave signal reflected by the target as the guidance basis.]
In the “Patriot” air defense and antimissile system before PAC-3, the terminal stage of the missile adopts the TVM guidance mode, that is, the “via missile” guidance mode. Why “via missiles”? Because of the traditional command guidance method, the radar directly sends commands to the missile, its guidance accuracy, especially the line error caused by the angle measurement error, will decrease with the increase of the target distance until it is unacceptable.
TVM guidance mode is to install a radio direction finder for the missile, which can accurately measure the azimuth angle of the target by receiving the reflected radar wave. As the missile and the target get closer, its measurement accuracy becomes higher. The missile transmits the azimuth information to the radar through the downlink data link. The radar then fuses the target data obtained by itself to accurately calculate the azimuth, distance, speed and other information of the target, and then transmits the guidance command to the missile to control the missile to hit the target.
TVM guidance solves the technical problem of attacking multiple long-range targets. The problem lies in the heavy workload of the radar, which not only needs to search and track the target, but also needs to receive the information transmitted by the missile and send commands to control the missile. Moreover, the missile has a certain time delay from detecting the target, transmitting information, and then receiving instructions, and the error is large when intercepting the high-speed target such as ballistic missile.
The PAC-3 missile uses a millimeter wave active radar seeker at the end, which greatly increases the guidance accuracy and can directly hit.
Compared with the an / mpq-53 radar, the an / mpq-65 radar adds a second traveling wave tube (TWT) to increase the search and tracking capability, and the engagement algorithm is also improved. It can meet both TVM guidance and terminal active radar guidance, and guide PAC-2 missiles and PAC-3 missiles.
Patriot PAC-3 missile.
The two radars mentioned above are passive phased array radars. The latest an / mpq-65a is an active phased array radar using gallium nitride transceiver components. The radar is developed by Raytheon company and has greater detection range, anti-jamming capability and identification capability. In addition, in addition to the main array, two new small arrays for detecting the side and rear are added. The size is one fourth of the main array and provides 360 degree coverage. The radar is planned to be put into use in 2022.
On the basis of PAC-3 missile, Lockheed Martin company has developed PAC-3 “segmented enhanced” (MSE) missile, which uses larger double pulse engine and larger wing, and modifies other structures to improve mobility, range and firing height.
On October 6, 2015, the US Army received the first batch of PAC-3 MSEs. The reason why it is called segmented enhanced type mainly refers to the improvement and enhancement of the engine section. The PAC-3 MSE is heavier than the previous PAC-3, which will reduce the number that can be carried on the transmitter from 16 to 12.
Different data sources give different ranges for the maximum range and firing height parameters of patriot-3 missile. It is generally believed that the maximum intercepting height of PAC-3 missiles against ballistic missiles is not more than 25000 meters, and the maximum intercepting distance is about 20-30 kilometers. It is mainly used to intercept medium and short-range ballistic missiles. The range of the segmented enhanced PAC-3 MSE will be larger. Some sources say that its range has been increased to more than 35km.
I have experienced real battles, and I have mixed feelings
Before the Gulf War, ballistic missile defense was a concept that had never been tested in actual combat. The Patriot pioneered the interception of ballistic missiles in actual combat.
However, behind the glitter, there is some embarrassment.
During Operation Desert Storm, the US military attacked Iraqi targets from bases in Saudi Arabia. ?
During Operation Desert Storm, in addition to air defense missions, “Patriot” was used to intercept Iraqi “Scud” launched at Israel and Saudi Arabia and the “Hussein” short-range ballistic missile developed on its basis.
Many media reported that the first “combat use” of the “Patriot” occurred on January 18, 1991. In fact, it was an “Oolong” event. At that time, its computer broke down, and no “Scud” shot at Saudi Arabia that day. The event was widely misreported as
“This is the first time in history that we have successfully intercepted enemy ballistic missiles.”.
Throughout the war, Patriot missiles engaged more than 40 ballistic missiles. On February 15, 1991, US President George H.W. Bush went to Raytheon’s “Patriot” manufacturing plant in Andover, Massachusetts. He declared there that during the Gulf War, the “patriots” engaged 42 “Scud” and intercepted 41. According to this statement, the interception success rate exceeded 97%.
On April 7, 1992, Theodore Postol of the Massachusetts Institute of technology and Reuven pedatzur of Tel Aviv University testified before the US House of Representatives committee that according to their independent analysis of the video tape, the success rate of the “Patriot” system was less than 10%, or even zero.
Of course, their doubts are also questioned.
On the same day, Charles A. zraket of the Kennedy School of Harvard University and Peter D. Zimmerman of the center for strategic and international studies testified on the calculation of the success rate and accuracy of the “patriots” deployed by Israel and Saudi Arabia, and disagreed with many statements and methods in the bostor report. Peter Zimmerman questioned bostall’s analysis and pointed out that the debris of Scud missiles falling in Saudi Arabia was full of fragments of the Patriot warhead.
I am afraid that the interception effect of the “Patriot” in the first Gulf War will always be a mystery, but one thing is certain: it is obviously impossible to achieve a success rate of 97%.
During the Gulf War, the “Patriot” missile also failed to intercept because of a major technical problem, which indirectly caused heavy casualties to the US military. On February 25, 1991, an Iraqi “Scud” missile attacked the Daran military camp in Saudi Arabia, killing 28 soldiers of the 14th Quartermaster detachment of the US Army. The interception failure was caused by a software error in the Patriot system.
Patriot was sent to Iraq for the second time in 2003 to provide air defense and missile defense capabilities for the invading forces. This time, it intercepted 9 missiles, including Al Samoud 2 and Ababil-100 tactical ballistic missiles, of which 6 were intercepted by gem type missiles, 1 by gem + and 2 by PAC-3.
On March 27, 2003, two “Patriot” missiles successfully intercepted an Al Samoud 2 missile launched by the Iraqi army from the north of Basra to the Doha barracks in Kuwait, the supreme headquarters of the Allied forces, thus avoiding possible heavy losses to the Allied forces.
For the 15 missiles that were not intercepted, the US military decided that the Iraqi missiles would not pose a threat because of their poor accuracy and stability, so it took the initiative to give up interception. However, at least one cruise missile modified from an anti-ship missile successfully penetrated the air defense network and landed near a shopping center in Kuwait.
Although the “patriots” have “long eyes”, they still refuse to recognize each other when fighting, and even fight their own people even harder.
On March 23, 2003, “Patriot” shot down a RAF “gust” fighter, killing two crew members. However, the next day, the U.S. Air Force’s F-16CJ wild weasel fighter “returned the color”.
The next day, a U.S. Air Force F-16CJ was locked by the radar of the “Patriot” missile. Just when the “Patriot” was preparing to launch missiles at the aircraft, the F-16CJ “started first, and launched a” ham “anti radiation missile, destroying the” Patriot “radar system.
A few days later, the “patriots” once again became powerful. This time, the US Navy was unlucky. On April 2, two PAC-3 missiles shot down a US Navy f / A-18 “hornet” fighter, and the pilot Nathan White became the enemy of the “Patriot”.
On July 11, 2018, an Israeli military helicopter searched the Syrian Israeli border area for the remains of a UAV shot down by Patriot missiles.
After the Iraq war, the “patriots” equipped by Israel, Saudi Arabia, the United Arab Emirates and other countries also shot down drones and short-range ballistic missiles used by Hussein’s armed forces.
What if the opponent doesn’t cooperate?
The “Patriot” faces a relatively elementary opponent, and it is also relatively cooperative.
First of all, these ballistic missiles intercepted by patriot still adopt the technology of head body separation. The radar scattering area (RCS) is relatively large and it is relatively easy to detect and lock.
Second, the range of these ballistic missiles is relatively low, the maximum speed and reentry speed (reentry refers to the reentry of ballistic missile warheads into the atmosphere) are also low, and the interception difficulty is also low.
Finally, the technical level of these missiles is roughly in the 1960s, and there are basically no penetration devices and penetration means. They can neither maneuver and orbit change to “hide” nor have any false targets, that is, they just plunge down.
If the cooperation is not good, the hit rate of “Patriot” will be greatly reduced.
During the Gulf War, Iraq redesigned the Scud to reduce the weight of the warhead, and at the same time increased the fuel tank to increase the speed and range. However, these changes weakened the missile structure, made it unstable during flight, and made the Scud disintegrate during re-entry. Once disintegrated, more targets may appear, and as a result, the Patriot does not know which part contains warheads. This is also regarded by the US side as the reason why the interception probability is not high.
Advanced ballistic missiles have more means to implement penetration. In the face of such missiles, the “patriots” can not catch them:
First, most of the advanced ballistic missiles use the head body separation technology. Some warheads also use stealth coating. The radar reflection cross-sectional area of the warhead becomes smaller, which greatly reduces the acquisition distance of the ground radar and also reduces the locking distance of the missile seeker. The closer the missile seeker is locked, the greater the accumulated error caused before. The missile must be corrected in such a short time within such a short distance, which may cause “confusion”.
Second, advanced ballistic missiles generally adopt mobile orbit change technology, which may be the orbit change in the middle and end stages, or spiral maneuver. According to Russian media, its “Iskander” ballistic missile can maneuver with an overload of more than 9g during terminal reentry, which greatly increases the interception error. Especially for PAC-3 missiles with direct collision and kinetic kill, the direct collision is more difficult.
Third, bait technology is also widely used in advanced ballistic missiles. In the Russian Ukrainian conflict some time ago, the “Iskander” missile was exposed, and some baits were released through the “window” of the tail. These decoys imitate the radar signal characteristics of the missile to the maximum extent. Some decoys are also equivalent to a small jammer, which is used to jam the ground radar or the missile seeker.
Fourth, when intercepting ballistic missiles, the “Patriot” is greatly restricted in its deployment, and the threat it faces is not limited to ballistic missiles. We may feel that if we meet the two conditions of maximum interception distance and maximum interception height, everything will be all right. In fact, it is still far from enough. In order to intercept an incoming ballistic missile, the terminal anti missile system usually needs to be deployed behind the landing point (or defense target). However, at this time, intercepting the other side’s cruise missiles becomes a big problem, because it may make it difficult to detect ultra-low flying cruise missiles.
Fifth, “Patriot” uses Anti Ballistic interception technology. The missile first flew to the advance route of the incoming ballistic missile, and then hit it head-on. This has additional requirements on the distance of its launching device from the landing point, or the distance from the protection target. The route shortcut (the vertical distance between the guidance missile position and the velocity vector of the air target projected on the horizontal plane) shall not exceed the limit conditions. Therefore, the conditions for terminal antimissile are extremely harsh.
Therefore, there is a saying in the antimissile field, “if you are not afraid of an incoming missile hitting accurately, you are afraid of hitting accurately.” This is like setting a trap around the defense target for an incoming missile, but it is difficult to catch the target if the missile suddenly deviates from the trap when it comes.
It is precisely because the “Patriot” has so many limitations that the United States has developed the “THAAD” regional anti missile system. The “THAAD” system is called the “terminal high altitude regional anti missile” system. In fact, its intercepting position is already in the middle of many missiles; In order to effectively coordinate with the “patriots”, the barrier between the “patriots” and the “patriots” has been broken in recent years. The “THAAD” system can launch and guide Patriot interceptors.
At the same time, the penetration technology of missiles is also developing, especially the development of hypersonic missiles, which brings troubles to the anti missile system. In general, ballistic missiles and hypersonic missiles still dominate in the contradictory confrontation between missiles and anti missile systems.