Air Defense: Self-Propelled Iron Dome


August 17, 2023: All the tweaks, tests and training have been completed for the new American mobile Iron Dome system. A year ago, the U.S. Marine Corps successfully tested Israel’s Iron Dome Tamir missiles as part of its mobile MRIC (Medium-Range Intercept Capability) system. Existing Iron Dome missile launchers hold 20 Tamir missiles. Each 160mm diameter Tamir weighs 90 kg (200 pounds) and is three meters (nearly ten feet) long. Tamir’s guidance system has a radar and a proximity fuze which detects the size and speed of a nearby target and detonates the warhead only if the right type of target (UAV, cruise missile or rocket) is detected. Because of added U.S. features (for destroying cruise missiles and UAVs), the cost per Tamir missile went from $50,000 to nearly $150,000. MRIC uses its Tamir missiles in conjunction with a U.S. Marine radar and command and control system. For MRIC the U.S. will also manufacture Tamir missiles but rebrand them as Skyhunter missiles.

The U.S. Army's HEMTT (Heavy Expanded Mobility Tactical Truck) is used to carry a mobile Iron Dome system for use by the army and the marines. HEMTT is also known as the M-977. These vehicles have a diesel-electric drive so there is plenty of power for the radar and electric motors used by an anti-aircraft system. The 8x8 HEMTT trucks are built for cross country operations and were able to keep up with armored formations during the 1991 and 2003 wars. Most of the 13,000 army HEMTT normally haul nine tons of cargo or 2500 gallons of fuel. That’s enough capacity for a mobile Iron Dome. The HEMTT began to enter service in the late 1980s, and cost about $200,000 each depending on special equipment and configuration. Starting in 2004, the HEMTT fleet began a refurbishment program, at about half their original purchase cost, to give the trucks another ten years of life. This included development of a version that used the diesel-electric drive. When HEMTT vehicles wear out, the army buys new ones. So far the army has purchased over 35,000 of these vehicles and production continues.

Meanwhile, in 2020 Tamir proved its ability to down cruise missiles and UAVs using the Iron Dome radar and fire control system. In that test Iron Dome systems on land and Israeli ships were integrated into a multi-layer air defense system that included David’s Sling (similar to Patriot) and the Arrow ABM (anti-ballistic missile system). MRIC can use other air defense search, fire control and targeting management systems. With that Israel began offering the Tamir missiles and launchers for customers like the American MRIC.

Continuous Israeli upgrades of Iron Dome enabled it to shoot down various types of UAVs. This required some software modifications and was done at the request of the U.S. Army. Iron Dome was already capable of shooting down aircraft and helicopters. The UAVs were often much smaller, but so are the rockets and mortar shells Iron Dome can knock down. The United States has contributed over a billion dollars to development and procurement of Iron Dome. Periodically adding new features like this helps export sales.

The U.S. Army was impressed and that led to developing MRIC to support mobile combat units. Iron Dome has been in service since 2011 and has proven itself in combat. Iron Dome uses two radars to quickly calculate the trajectory of the incoming rocket and do nothing if the rocket trajectory indicates it is going to land in an uninhabited area. But if the computers predict a rocket coming down in an inhabited area one (or often two to be sure) $50,000 Tamir guided missiles are fired to intercept the rocket. This, and the fact that the Iron Dome fire control system can track hundreds of incoming missiles at once, makes the system cost-effective. So far Iron Dome has shot down over 800 rockets, which is about 85 percent of the rockets it calculated were headed for a populated area. The Tamir missiles are effective against rockets, mortar shells and artillery shells up to 155mm. Iron Dome can also shoot down aircraft and helicopters at altitudes up to 10 kilometers/32,000 feet. Iron Dome is Israel’s principal defense against short range rockets fired from Gaza or Lebanon. Work is underway to increase the Iron Dome range from 70 to over 200 kilometers but that is stalled because of budget shortages.

The MRIC radar operates differently to determine which incoming threat justifies an interceptor missile. In a combat situation, the areas to be defended often change. MRIC provides marines or soldiers moving into a new area with protection against the most threatening rocket, artillery or mortar fire. This gives the advancing forces an edge and demoralizes defenders.

Israel initially designed Iron Dome to only defend stationary targets. By 2014 Israel had fifteen batteries of Iron Dome and over 2,000 Tamir missiles. That was enough to shut down the Hamas effort to hit Israel with thousands of rockets. Each battery has radar, fire control equipment, and 3-4 missile launchers (each with 20 missiles) and cost about $37-50 million for the basic (no anti-aircraft capability) depending on how many missiles it is shipped with. With the new system, a battery with two radars and three launchers costs about $100 million and can protect an area of about 150 square kilometers.

In 2014 the U.S. Army purchased an Iron Dome anti-rocket battery from Israel, mainly to determine if Iron Dome would be worth getting for deployment in Iraq and Afghanistan where American troops were still stationed. This American purchase was the first export sale of Iron Dome. The U.S. bought two more batteries in 2020 and 2021. Israeli efforts to export their Iron Dome anti-rocket system were slow initially but eventually succeeded with Azerbaijan, India and several other counters placing orders. The Israeli manufacturer of Iron Dome thought this would make Iron Dome a hot export item. After all, Israel is one of the top ten weapons exporters in the world. This is because the Israeli system works well and is usually combat tested. Although the Iron Dome system had succeeded in shooting down about 85 percent of the rockets headed for Israeli populated areas, that was a unique situation. Continued success eventually made Iron Dome exportable, especially after the anti-aircraft, UAV and cruise missile capabilities were added. The U.S. was willing to buy more Iron Dome systems but wanted access to the fire control source code. Israel refused because American security is less strict than Israel’s and a leak of that source code would enable an enemy to determine exploitable weaknesses in Iron Dome. This software dispute was eventually resolved.

The main problem is that Iron Dome was designed to deal with an enemy that is a terrorist organization (Hamas) operating out of an area (Gaza) that is basically home for Palestinian refugees who have been there for over 60 years and want nothing less than the destruction of Israel. A similar organization (Hezbollah) controls southern Lebanon and is also dedicated to the destruction of Israel, using 40,000 unguided rockets they received from Iran. This is the unique situation that Iron Dome was designed to deal with. When faced with a massive launch of rockets at once, Iron Dome is unable to shoot down all of those headed for populated areas. While the intercept rate is lower, Iron Dome has shown it can still reduce Israeli casualties and property damage. Iron Dome recently added a high-powered laser device that can knock down many rockets but at shorter ranges. MRIC may also receive the laser weapon as well but it will require a large generator on the MRIC to supply the power.




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