Air Weapons: Evolution Beats Revolution


March 5, 2016: The U.S. Navy has decided to put the latest (Block III) version of the AGM-154 JSOW (Joint Stand Off Weapon) glide bomb into mass production and make this version the current standard. What makes Block III special is that it has a Link-16 digital data link and is equipped to go after moving ships. Block III carried out its first successful test of this in 2014. The video link/heat sensing guidance system was also accurate enough to locate and find a cave entrance, fly into it and then detonate. Two missiles were tested and both were able to do it. This was part of ongoing upgrades for JSOW. The last round of tests in 2015 verify that the new software can handle a wide variety of moving ship targets. This final round of tests included verifying that Block III can handle electronic countermeasures.

JSOW has been continually upgraded since the 1990s. In 2013 the powered (ER for extended range) version of JSOW completed its testing. Earlier problems with the fuel system were fixed and this enabled the small jet engine to propel a JSOW nearly 500 kilometers. Normally, JSOW is unpowered but able to glide for up to 22-130 kilometers (depending on the altitude it is dropped from). The powered version (JSOW-ER) had been in development for six years and has been delayed by technical problems and a shortage of customers.

JSOW first entered service in the late 1990s. Australia, Canada, Greece, Finland, Poland, Singapore, Turkey, and the Netherlands have bought small quantities. The U.S. Navy and Air Force have bought over a thousand and used 400 in the Balkans, Iraq, and Afghanistan. The long range and cave finding versions are apparently sending a message to Iran and North Korea.

The JSOW is becoming a popular, if specialized, smart bomb, even though it has had little use in combat. JSOW is basically a smart bomb with wings. That enables it to glide up to 130 kilometers. Range is about 22 kilometers if dropped from low altitude. JSOW also contains more elaborate fins and software that enables it to follow a specific route. Like the wingless JDAM smart bomb, JSOW uses GPS and inertial guidance (as a backup) to find its target. The C version has a terminal guidance system using IR (infrared, as in heat, sensors) for additional precision. Like JDAM, JSOW will hit within 10 meters (31 feet) of its aiming point just using GPS (or about 30 meters is using the backup INS system). JSOW can also attack moving ships.

There are three types of JSOW warheads. AGM-154A carries 145 bomblets that attack personnel and vehicles. AGM-154B contains six SADARM bomblets that seek out and destroy armored vehicles in an area 300 by 600 meters. This one costs $490,000 each. The AGM-154C carries a 361 kg (794 pound) warhead that can penetrate concrete or earth before detonating the high explosives it carries. This model contains a video link that allows for hitting very small targets (like going through a window). The C1 version is able to hit moving targets.

Each JSOW weighs 500-618 kg (1,100-1,500 pounds), depending on type. Not a lot of JSOWs have been bought because there is not a lot of demand for them. The purpose of a standoff weapon is to keep the aircraft away from enemy anti-aircraft defenses (mainly missiles). Some JSOW have been used in Iraq (between 1999 and 2003) and Afghanistan (2001). But in most cases, the much cheaper JDAM (about $30,000 each) does the job just as well. But against a better equipped foe, like China, Syria, Iran, or North Korea, JSOW would be more useful, and that’s why JSOW remains in production and development continued on JSOW ER.

JSOW ER is similar to JASSM a heavier and longer range missile that entered service over a decade after JSOW and the development delays caused the U.S. Navy to back out of the JASSM program as JSOW ER and SLAM ER did what the navy needed and it could save a lot of cash and hassle by leaving JASSM to the U.S. Air Force. The delays in getting JASSM into service enabled improved JSOWs to take a lot of the business JASSM was going after. Sometimes better isn’t good enough if it’s too late to arrive. JSOW entered service in 1998 while JASSM was not ready until 2011.




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