Another Cold War era weapon (SADARM) has shown up in Ukraine, doing what it was designed for; destroy Russian tanks. Two NATO members (Germany and Sweden) manufacture 155mm artillery shells carrying two each Sense and Destroy Armor Munitions. Originally called SADARM munitions by its American developer (Textron) it had completed development when the Cold War suddenly ended in 1991. SADARM was not as effective as expected and the 155mm version was canceled in 2001. The U.S. Air Force has more success with the SADARM submunitions used in the CBU-105 cluster bomb (40 submunitions per half ton cluster bomb) because a bomb undergoes much less stress when used than an artillery shell. The air force and six export customers purchased hundreds of these bombs but sales were not high enough to keep CBU-105 in production after 2017.
Meanwhile the U.S. Army noticed the success of an improved German SADARM shell called SMART as well as the similar Swedish Bonus. Both entered service in 2000 and both were successful as “SADARM 2.0”. The U.S. Army began ordering BONUS shells in 2018 and ordered more in 2020.
BONUS is described as a fire and forget guided 155-millimeter ammunition designed for destroying armored targets. BONUS was a joint project by Britain, France and Sweden with the Swedes taking the lead in production. BONUS can be fired from standard NATO 155mm artillery and has a maximum 35-kilometer effective range. The round carries two submunitions, each with their own multiband IR (heat) sensors backed by laser radar. BONUS uses small winglets to slow its descent rather than small parachutes that are used in earlier similar submunitions, like the German SMART shell. The parachutes are easier to spot and more expensive and complex to use.
The submunitions separate from the shell over the target location (using a time on target fuze) about 175 meters above the target areas and scan for targets. Each warhead can scan about 32,000 square meters and hit even moving targets within that area. The destruction is achieved by an Explosively Formed Penetrator (EFP) able to punch through more than 130 mm (five inches) of armor. This doesn’t seem like much but the tank armor is strongest at the front and not at rear or top. The only defense against this “top attack'' EFP is APS (Active Protection Systems) such as Trophy, but even these have difficulty dealing with things like EFPs. The APS systems work great against HEAT warheads because these disperse cumulative streams of superheated gasses, but not against molten metal projectile formed by an EFP. Moreover, thanks to two submunitions per shell, the artillery pieces remain for a shorter time on their firing position, so they are less likely to get caught by enemy counter-battery fire. The major defect of SADARM shells is that they are much more expensive than GPS guided Excalibur shells.
Each submunition weighs 3.4 kg (7.5 pounds) and uses 945 g (2.08 pounds) of Octol explosives, which was designed to effectively form the self-forging penetrator. Most of the submunition weight goes to the sensors (including batteries) and design elements that slow descent and rotate the sensors to find a target.
The American M898 SADARM (Search And Destroy Armor Munitions) dates back to the late 1970s when the U.S. Army started to look for a “smart” anti-armor 155 mm projectile. About a decade later SADARM had been developed and prototypes built but due budget restrictions in 1990 the program was slowed down. In 1993 the first tests were unsatisfactory because SADARM hadn't been able to hit a moving target and overall accuracy was poor. The manufacturer promised to improve the technology, and a year later the program was approved for limited low-rate production. Unfortunately for SADARM the later (1995, 1998 and 1999) tests showed only a little improvement. In all trials, the SADARM struggled to get an 80 percent reliability rate. This together with significant cost overruns were reason enough to end production in 2001. This failure did not mean the end of the SFW submunition technology, which was subsequently adopted by the U.S. Air Force as well as the developers of the SMART and BONUS shells. The submunition was always meant to be carried by a wide variety of projectiles including MLRS rockets, mortar shells and cluster bombs.
Reliability of the SADARM submunition improved enough to work as the payload of CBU-105 half ton cluster bombs. Each of these bombs carries and disperses 40 submunitions Each SADARM submunitions has their own radar and heat sensor that searches for armored vehicles below and destroys them. SADARM sensors can search and attack vehicles within an area of roughly 150 x 360 meters, as they slowly descend. The self-forging metal projectile used by the SADARM submunition punches through the thinner armor on the top of the vehicle. If a target is not found, SADARM self-destructs. CNU-105 has not shown up in Ukraine because the Russians rarely use large enough concentrations of armored vehicles to justify use of CBU-105. Ukraine prefers to save it aircraft for air defense and use artillery and guided rockets for distant targets.
The first use of the CBU-105 was in early 2003, when a B-52 dropped six of them on an Iraqi army column moving south from Baghdad. Most of the vehicles were later found destroyed. Since then, there have been several export customers for CBU-105 and the U.S. Air Force still has them stockpiled for future use even though production ceased in 2017.
The Russians have a version of their own, SPBE-D, for sale to anyone who can pay for it. The American CBU-105 is preferred because the United States pioneered the technology, and demonstrated it could work in combat. India faces a large force of Pakistani tanks, and CBU-105 is an inexpensive and quick way to destroy lots of armored vehicles.
Russia eventually responded to the SADARM submunition threat by developing a new generation of ERA (Explosive Reactive Armor) that now covers the top of the turret and engine compartment of their tanks. In theory the new ERA should protect against SFW or at least reduce SFW effectiveness. So far ERA protections do not appear to be working against SFW.