When the term “active protection for tanks” is mentioned, the first system that comes to mind is the Trophy system, developed by Rafael and fitted to IDF Merkava Mark-IV tanks. It is one of two operational systems in this category, worldwide. The other system is known as Arena, and it was developed by Russia. The Russian system is considered operational, but no hard evidence exists about the use of this system on the battlefield, except for rumors according to which it was tested during the second conflict in Chechnya. On the other hand, the world received the first testimony of the “baptism by fire” of the Trophy system in March 2011, when an RPG antitank rocket fired from a short range toward an IDF Merkava Mark-IV tank, close to the border with the Gaza Strip, was neutralized by the system. The system generated media waves once again when, during Operation Protective Edge, it enabled the IDF tanks to operate freely in an environment abundant with antitank weapons, like the city of Gaza and its surrounding areas.
The Iron Fist system, developed by IMI, has not been featured in the headlines yet, as it had not become operational, but this system offers performance characteristics that are by no means inferior to those of the Trophy system or the Russian-made Arena system, at least as far as the trial results presented by IMI indicate. However, last December, IMOD decided to develop a single active protection system for IDF, so the Ministry compelled the industries to sit around the same table and develop a system that would provide IDF with the advantages of both systems in a new system, a “second generation Trophy system”, if you will.
To better understand what the Iron Fist system does, I paid a visit to IMI headquarters, for a conversation with Danny Peretz – IMI VP R&D, and with Haim Keret, Head of IMI’s Armor & Engineering Administration. Right at the outset of the conversation, they made it clear to me that the objective of the development of the Iron First system was to provide tanks with ultimate protection against any threat. “In order to accomplish that objective, we developed the solution in layers,” explains Peretz. “If one layer fails, the other layer will back it up.”
The reference threat for the system is an antitank missile penetrating the tank by using the shaped charge method. “It is an explosive charge built in a certain way that creates a long copper rod capable of penetrating anything. The Kornet missile can penetrate more than one meter of steel,” explains Peretz. “The idea was how to intercept the missile before this jet is generated. If you managed that, you would be able to provide protection against almost anything.” The solution by IMI is based on four layers. The first layer, closest to the tank, is the passive/reactive armor. It is not a part of the Iron Fist system, but the basic armor protection each IDF Merkava tank is fitted with. This armor protection is developed and manufactured by IMI. This is, in fact, the last protective layer before the threat would hit the tank and the crew – if it succeeded in penetrating all the other layers.
The Iron Fist system is fitted “above” the basic armor protection. It consists of three layers: the first layer issues the alert. It consists of Radars by RADA along with electro-optical and optical devices. The second layer is a “soft kill” protective layer, intended to deceive the antitank missile operator using a powerful laser light. In this way, the operator believes the target is located away from the actual position of the tank, so he undershoots and the missile hits the ground short of the tank. This layer is relevant to second-generation antitank missile systems. More sophisticated missiles, like Rafael’s Spike missile, are autonomous (“fire-and-forget”), so this type of deception is not relevant to them.
The third layer consists of a “steel wall” that stops antitank missiles of any generation. This layer consists of an interceptor that is launched toward the threat and explodes at a distance of 50 to 80 cm from the threat, opposite its center mass, and in fact breaks the incoming antitank missile in two. The people at IMI explain that neutralizing the threat in this manner provides an advantage, as the threat is not initiated. “The RPG rocket has a piezo-electric crystal at the front that needs an impact in order to be initiated. We hit the threat from the side, so it does not explode. Other missiles have a collapsing dome. It has to collapse in order to activate the warhead. As our interceptor hits it from the side, the dome does not collapse. Even when you have an accelerometer, the impact is a side impact rather than a frontal impact, so the missile will not be activated. We cannot say that even one in one hundred will not be activated, but most of them will not be activated and that is a tremendous advantage,” explains Peretz.
When IMI developed the system, the original prototype included six launching tubes. Subsequently, IDF requested to scale it down to four tubes, two on each side. The interceptors are loaded into the tubes from outside the turret, using a speedy method that only takes a few minutes. However, in a sniper-infested environment, the tank must be located behind a protective barrier. The loading of the Trophy system interceptors is carried out in a similar manner.
In addition to its tank protection ability, the system can also spot the source of fire. This is important for two reasons: one – so that the missile operators will not fire at you again, and two – so that they will not fire at the other tanks in your unit. The system can cope with missiles fired at the tank from a range of a few dozens of meters or from a range of a few kilometers, as in the case of the Kornet missile. It does so by reverse-calculating the missile’s trajectory. The people at IMI say that the system is accurate to within 10 to 30 meters. “It’s not pin-point, but it’s enough to handle the threat,” they explain.
The primary differentiation between the systems involves the way in which each of them handles kinetic energy rounds (or kinetic energy penetrators). The Trophy system handles threats with warheads, while the Iron Fist system can also handle kinetic energy rounds. A kinetic energy (KE) round is a long tungsten rod, shaped like an arrow, with a sharp point and stabilizing fins. To fit the caliber of the cannon firing it, the round is surrounded by a plastic shell called a Sabot, which separates from the round after it leaves the cannon. IMI, Rafael and the IDF Ordnance Corps were world pioneers in the development of such armor-piercing rounds, and the first KE round that entered service in IDF was known as Lituf (APFSDS - Armor-Piercing Fin-Stabilized Discarding Sabot). KE rounds of this type were used by the IDF 421st Brigade, the first IDF armored brigade that crossed the Suez Canal in the Yom-Kippur War of 1973, against the Egyptian armored formations.
“It is a long, thin rod that leaves the barrel at a speed of 1,600 meters per second. Its depth of penetration equals the length of the rod. How do you stop it? You shift it by an explosion,” explains Peretz. “The idea is to tilt it off course, and then it would not hit the target with its sharp point but with its body, thereby losing energy. The ideal is to rotate it by 90 degrees, but that is very difficult to accomplish. In effect, tilting the trajectory of the round by 7 degrees is enough to cause it to lose 80% of its energy and penetrate 30 to 40 mm of armor maximum. It will penetrate a light APC even in this case, reaching from one side to the other, but it would not damage a tank. Such a round costs several thousands of dollars and it is very cheap compared to other round/missile types.”
What was the logic behind the development of this system? Admittedly, an active protection system for tanks is the utmost aspiration of any modern military leader, but in reality, apart from Israel and Russia, no country has acquired such systems. In fact, it seems that despite the breakthrough technology, most states do not hasten to adopt the concept by purchasing these systems. “Many countries attempt to develop such systems independently – so far without success. Others enter cooperative alliances with those that already developed such systems. It is a direction in which everyone is heading,” says Keret. “The problem is the cost and the fact that the system is categorized under the definition of Killer Robots. This system operates entirely autonomously, without any human operator intervention, and although it is a defensive system, it fires ordnance toward the threat.
“The reason for this autonomy is the speed of response required for handling such threats as antitank missiles or KE rounds. A person cannot do that. In the State of Israel, the reason for the development of such a system is protecting human lives. On the other hand, around the world autonomous systems are still frowned upon, even if they are intended for defensive purposes. Clients raise questions like what happens to the crew, what happens to the environment around the tank, is an autonomous system that operates without crew intervention is acceptable or not from an ethical point of view – all of these are questions being raised in military organizations around the world in the context of such systems.”
As far as the price aspect is concerned, the feasibility of the system is measured relative to the potential damage that may be sustained by the tank. However, the people at IMI say that such a ratio does not justify the investment in an active protection system. According to open sources, the Trophy system costs about US$ 300,000 or more. The cost of repairing the tank is negligible in comparison. One should also bear in mind that the protection system also needs to be maintained, so as far as price is concerned – it is not so certain whether the system is worthwhile.
With regard to the operational aspect, this system offers a tremendous advantage, say the people at IMI. “The warfighters feel safe and fight differently. Reactive armor entered service during the First Lebanon War. There were incidents where tank crews removed armor plates from damaged tanks, fitted them to their own tanks and then fought differently. They felt safe on the battlefield. They are not afraid to ascend into a firing position, and that affects the results of the battle,” explains Peretz.
Keret cites another reason. According to him, other countries around the world are not involved in combat scenarios like those in which IDF is involved. “That is why there is no pressure to install these systems,” says Keret. “At NATO they are trying to come up with a standard for active protection. It is still at the draft phase, but in the right direction. Tank manufacturers are also trying to develop such systems or to enter cooperative alliances with companies that have already developed such systems. It takes the rest of the world longer to adopt these systems.”
Why did IDF choose the Trophy system?
According to Peretz, people started thinking about these systems about 30 years ago. Back then, the technological ability to accomplish it was not yet available, but the idea of stopping missiles has been around for a long time. “At some point in history, Rafael and IMI were working on those ideas. It took a long time. Some of the financing came from IMOD and most of the development budget came from the companies’ own budgets. Rafael was at a better economic state than IMI, and this enabled it to invest more resources in this effort. In 2006, following the Second Lebanon War, IMOD wanted a system and Rafael was better prepared. The idea was to conduct a competition between the companies at a later stage, to see whether one of the systems was superior.”
History notwithstanding, the people at IMI put the past aside and look ahead. “At the present time, the IDF has specified the requirements to be met by the system, and Rafael, IMI and Elta must sit around the same table for a series of meetings,” says Keret. “The objective is to initiate a joint brain-storming effort and come up with one system that meets the requirements of IDF. Eventually, the industries will also have to come up with a business model that everyone would benefit from. In the end, when you leave the engineers to do their work, they do not care whether they work for Rafael, IMI or Elta. They have a goal and they will accomplish it. The new system will be better than the Trophy system and the Iron Fist system separately.”
The people at IMI say further that the privatization process the company is preparing for will have no effect on the development of the new system. On the contrary. Along with the development of the system for tanks, IMI developed a lighter version for light combat vehicles designated Bright Arrow. In that case, the system provides protection against antitank missiles only – not against KE rounds. It consists of a weapon station and an integrated protection system. When an antitank missile is launched at the vehicle, the system will neutralize the weapon station, address the incoming threat and destroy it by firing an interceptor. Subsequently, it will resume its role as a weapon station. All of this takes place autonomously, while the vehicle is in motion. “Our system can protect M-113 APCs, HUMVEEs, Namer APCs and other vehicles of the same category,” says Peretz.
What about the sea and air arenas? The people at IMI say that at the present time, naval vessels and helicopters are not as severely threatened as tanks are. “Many years ago they wanted to develop active protection for helicopters,” explains Peretz. “I can tell you that one day, such systems will be available. It is a consideration of the ratio between the severity of the threat and the damage inflicted on the helicopter during routine operation. Such a system weighs a lot and shifts the helicopter’s center of gravity. When the threats emerge – an active protection system will become a reality. We also think about offshore energy assets. At MAFAT they started to promote it opposite the three leading industries, and we are working in the direction of developing a system that would protect an asset like an offshore drilling rig.”
Another aspect of the development of the future system being considered at IMI is the question of protecting an individual tank or a group of tanks. In theory, one tank can protect another tank that travels alongside it. In effect, it is not the case at the present time. “In order to do it, you will need a stronger Radar and an interceptor with a longer range. That would bump the system cost and reduce its feasibility,” explains Peretz. “It depends on the requirements of the military. If the military wants to protect a tank formation (several tanks), then you will develop the system in a certain way. If the objective is protecting a single tank – that will call for a different development process.”