The U.S. Marine Corps has found new ways to use their M142 HIMARS (High Mobility Artillery Rocket System) vehicles firing GMLRS (GPS guided MLRS) rockets. There were two recent examples of this that have greatly improved the usefulness of HIMARS. In 2018 the Marines found that the multitude of sensors on their new F-35B vertical take-off jets could spot ground targets in all weather and at night and pass the target location on to a nearby HIMARS vehicle that would then fire a GMLRS rocket at the target. To maintain maximum stealth capabilities the F-35 carries bombs and missiles internally but the capacity of the internal bomb bays are limited. HIMARS can supply the guided weapons for one or more F-35Bs. Some helicopters are equipped with similar sensors and digital communications systems and can also pass on GPS target data to a HIMARS vehicle. An F-35B could even maintain its stealth by sending the target information via an encrypted burst transmission that is difficult to use for location finding.
The Marines recently added a third HIMARS battalion and are buying additional HIMARS resupply vehicles (in addition to the hundred they already have). The 28 ton Mk37 resupply vehicles carry two MLRS rocket pods and have the handling equipment to remove an empty pod from a HIMARS vehicle and replace it with a pod containing rockets. The HIMARS battalions and ammo supply units use the MK37s to move loaded and empty MLRS pods into and out of the combat zone.
In 2017 the marines found that with a few modifications to the HIAMRS fire control software the vehicle could accurately fire GMLRS rockets from the flight deck of one of the many amphibious ships marines operate from. Since World War II the U.S. has fired unguided rockets from ships in support of amphibious operations. But the use of GMLRS meant HIMARS could provide precision fire support from a ship at sea and the next version of GMLRS will have a range of 135 kilometers, making the ship-based version even more useful because it can support troops even farther inland. The long range version also makes HIMARS more effective at supplying F-35s in stealth mode with more guided missiles. This GMLRS has been successfully tested at ranges up to 110 kilometers. This TC-GMLRS (Tail Controlled Guided Multiple Launch Rocket System) rocket is the same size as the current GMLRS rocket.
The $6 million HIMARS system is a 6x6 U.S. Army truck with an armored (against small arms fire and shell fragments) crew cab carrying one MLRS (Multiple Launch Rocket System) six rocket pod instead of two in the original larger, tracked, MLRS vehicle. Initially, a major attraction was that the 12-ton HIMARS truck could fit into a C-130 transport (unlike the 22 ton tracked MLRS) and was much cheaper to operate. The HIMARS vehicle can move at up to 85 kilometers an hour on paved roads and travel 480 kilometers on internal fuel. In 2016 it was revealed that HIMARS vehicles in American service had reached a million operational hours with a 99 percent readiness rate. The tech HIMARS used enabled HIMARS to operate (move, receive a target order and launch the GMLRS) using as few as one of the normal three man crew. The first HIMARS entered service in 2005, about a year after GMLRS (GPS guided MLRS rockets) did. The two new innovations worked well together and were a major reason for the success of the GMLRS and the HIMARS rocket launcher. The U.S. no longer buys the tracked MLRS or unguided MLRS rockets.
GMLRS rockets have been in service since 2004. Like the unguided version, the GMLRS is packaged and used in containers (pods) holding six rockets each. The fire control system was upgraded to handle precision targeting rather than just a general area. Since 2004 over 3,000 GMLRS rockets have been fired in combat. GMLRS rockets cost about $100,000 each and have been very successful. That has meant even less work for tube artillery, which had dominated the battlefield since the 17th century. Export demand for HIMARS has meant the U.S. manufacturer has had to resume production for the growing number of foreign customers.
The 309 kg (680 pound) GMLRS missile is a GPS guided 227mm rocket. It was designed to have a range of 70 kilometers and the ability to land within meters of its intended target, at any range. This is possible because it uses GPS (plus a backup inertial guidance system) to find the target location it was programmed with. In 2008 the army tested GMLRS at max range (about 85 kilometers) and found that it worked fine. This enables one HIMARS vehicle to provide support over a frontage of 170 kilometers. Thus one HIMARS vehicle can provide precision fire support over an area of about 20,000 square kilometers. This is a huge footprint for a single weapon (an individual HIMARS vehicle), and fundamentally changes the way you deploy artillery in combat. By way of comparison, Excalibur (GPS guided 155mm shell) has a max range of 37 kilometers, and 120mm GPS guided mortars about 7.5 kilometers.
Early on most of the GMLRS rockets were fitted with an 89 kg (196 pound) M31A1 high explosive ("unitary") warhead. About half of that is actual explosives. That's twice as much explosive as the U.S. Air Force 130 kg (285 pound) SDB (Small Diameter Bomb). A 155mm artillery shell has 6.6 kg of explosives, and the 500 pound (227 kg) bomb has 127 kg of explosives, which produced an excessive blast for many urban combat situations. The GMLRS seemed to be just right most of the time. In 2014 an M30A1 warhead was introduced in 2016 and it used less explosive but added 180,000 tungsten pellets which were effective against personnel and unarmored vehicles over a much larger area. The larger GPS guided ATACMS rocket (one per MLRA pod) has a range of 300 kilometers and a 230 kg (500 pound) warhead.
GMLRS has been used with great success in Iraq, Afghanistan and Syria where most have been fired so far. The guided rocket is much more effective than the older, unguided, version, and has replaced it for most users. The accuracy of GMLRS means that one rocket does the job that previously required a dozen or more of the unguided ones. That's why HIMARS is so popular. While HIMARS only carries six rockets, that's often enough to last for days in places like Afghanistan, even when there's a lot of combat.
Because of precision weapons like GMLRS and smart bombs, since the end of the Cold War in 1991, the U.S. Army has drastically reorganized and reduced its artillery force. At the end of the Cold War most artillery was conventional “tube” artillery. That meant towed 105mm, 155mm, 203mm howitzers and self-propelled 155mm howitzers. The MLRS, a 12 tube 227mm unguided rockets was just entering service when the Cold War ended. In the 1990s it became obvious that smart bombs (JDAM) first used in the 1991 Gulf War, were more effective than artillery and that led to a major shift away from using artillery. By 2004 over 40 tube artillery battalions had been disbanded.
Noting the success of GMLRS, Russia and China have developed and put into service their own GPS guided rockets. Russia has long led in the design of new rocket systems was is playing catchup when it comes to using guided rockets. The multiple rocket launcher was first developed by the Russians before World War II as a cheap alternative to massed artillery fire by individual guns. Long seen as a supplement to regular artillery, the introduction of the high tech U.S. MLRS rocket system in the 1980s began to make a lot of conventional artillery obsolete even before GMLRS came along. Of course, artillery has always been ripe for innovation. The U.S. 175mm gun, introduced in the 1960s, was rendered obsolete in the 1980s with the introduction of special long range ammo for the 203mm (8 inch) howitzer. The U.S. Army stopped using the 175mm gun in the 1970s. When the MLRS entered service, one of the three batteries in each division's 203mm howitzer battalion was equipped with MLRS units instead. But MLRS proved so effective that the 203mm howitzer battalion became an MLRS battalion and the 203mm gun was dropped by the U.S. Army. Currently, the United States Army has seventeen HIMARS battalions while the Marines have two battalions. Each battalion has 18 HIMARS vehicles. The U.S. Army was quick to acquire HIMARS vehicles, receiving over 400 of them by 2011. That was enough to equip the current HIMARS battalions plus vehicles needed for training and spares.
There were always non-divisional MLRS battalions, as the MLRS was seen, from the beginning, as an ideal weapon for massed artillery fire. The Gulf War allowed the MLRS to show off what a potent weapon it could be. The larger rockets also provided room for more complex payloads (cluster and "smart" munitions) and guidance systems. This was another example of how technology can transform an old weapon. While the Russians have been using rocket launchers for over 70 years, they never got around to enhancing their effectiveness with a lot of technology until recently and then only because they noted others were doing so and succeeding. Now everyone is changing their artillery forces and adapting to the use of many fewer guided projectiles.