Air Weapons: Mutating Multipurpose Missiles


August 10, 2017: Cruise missiles designed for use on bombers and fighter bombers are increasingly popular for other uses. Thus the U.S. Navy recently carried out a successful test of its LRASM (Long-Range Anti-Ship Missile) launched from a container mounted at an angle on the deck of a ship. This version of LRASM used the same fire control hardware and software used for the VLS (Vertical Launch System) cells built into many new warships. The deck mounted LRASM makes it possible to install this anti-ship missile on older ships as well as some new ones (like aircraft carriers) that don’t have VLS.

LRASM is basically a new version of the existing AGM-158 JASSM (Joint Air-to-Surface Standoff Missile). This was recognized in 2015 when the air-launched version of LRASM was given the official designation of AGM-158C. This followed a 2014 decision to take the LRASM research project and put into service as a stopgap until a more advanced successor to the Tomahawk cruise missile is ready in the mid-2020s. The Tomahawk is one of the earliest examples of a guided missile that was originally designed for heavy bombers eventually going on to be a weapon for surface warships, submarines and shore based systems.

JASSM missiles are 1,045 kg (2,300 pound) weapons that are basically 455 kg (1,000 pound) JDAMS (GPS guided bombs) with a motor added. JASSM was designed to go after enemy air defense systems or targets deep in heavily defended (against air attack) enemy territory. LRSAM was based on JASSM ER, the version with the longest range (930 kilometers) but because of the additional sensors and electronics LRSAM weighs 1,100 kg (2,500 pounds) with a 450 kg (1,000 pound) warhead and a range of 560 kilometers. The air-launched version, mainly for the air force, is to enter service in 2018 while the naval version will be ready by 2019.

LRSAM began as a research project in 2009 to develop a stealthier cruise missile. LRASM was part of an effort to develop autonomous hunter-killer missiles that can seek out targets without remote control and in the midst of enemy countermeasures (electronic and otherwise). The LRASM underwent its first field test in 2013 when one was launched from a B-1B bomber and sent off in the direction where three destroyer size unmanned ships were moving about. LRASM flew via GPS waypoints for several hundred kilometers and then began flying a search pattern, seeking electronic or visual signs of one of the target ships. One was found and LRASM, armed with an inert warhead hit it.

LRASM is not just equipped to seek out targets in a general area (of several thousand square kilometers) but is also fitted out with electronics to resist GPS jamming and other anti-missile electronic defenses warships carry. LRASM also has a highly accurate INS (inertial guidance system) that cannot be jammed and serves as a backup to GPS. The ultimate LRASM design will also incorporate stealth features (a special shape and largely passive sensors). The original LRASM development model was basically an existing long range bomb (JASSM ER) with a much improved guidance system and that turned out to work.

One reason JASSM was selected as the basis for LRSAM was because JASSM went through a pretty tortuous development process itself. Work on JASSM began in the late 1990s and was expected to enter production by 2002 but that was delayed two years. Then there were more delays, lots of delays. From 2006 to 2009 the U.S. Department of Defense was on the verge of cancelling the $6 billion JASSM program. Lobbying, pleading, large orders from Australia and South Korea, and the growing possibility that the missile would be useful against Iranian, Chinese or North Korean air defense systems, gave the program a few more lives.

The only problem JASSM had was that, well, it often didn't work. Until 2009 the tests had been mostly failures. But the manufacturer was able to identify all the problems, and convinced the government that these were the result of poor manufacturing. This issue, the builder promised, was fixed. Fortunately tests in late 2009 were over 90 percent successful. That kind of good news has arrived just in time and JASSM finally entered service. Although the U.S. Air Force had ordered the AGM-158 JASSM into full production in early 2004 only a few were produced because of test failures. Air force purchasing plans were cut way back because of the reliability problems, and this delayed shipment of the missiles to combat units until 2011.

JASSM is stealthy and uses GPS and terminal (infrared) guidance to zero in on heavily defended targets (like air defense sites.) The terminal guidance enables the missile to land within three meters (ten feet) of the aiming point. If there were a war with North Korea, for example, JASSM would be essential to taking out enemy air defenses, or any other targets that have to be hit early in a war (before air defenses can be shut down.) This capability is apparently what attracted the South Koreans, who now have F-15K aircraft that can carry JASSM.

JASSM was designed to handle the most modern Russian surface to air missiles, which are also being sold to China. North Korea has older stuff, and can't afford the newer Russian SAMs. But even these older air defenses can be dangerous, and are best addressed with long range missiles. So there is a need for a missile like JASSM, at least one that works.




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