US reinforces Ukraine with upgraded anti-jammer missile bombs
Americans have made adjustments to the GLSDB system and are ready to resume deliveries to Ukraine. Let's present what makes the GLSDB missile bombs unique.
According to Reuters, the Americans have made GLSDB missile bombs resistant to Russian GPS signal jammers. This interference had caused the suspension of these weapons’ deliveries in 2024.
It's worth noting that GLSDB missile bombs, with a range of about 93 miles, serve as an excellent substitute for the initial versions of MGM-140 ATACMS ballistic missiles, which had a range of 103 miles. The U.S. had exhausted its supplies of these missiles. This available option to destroy Russian logistics or command points at a distance of over 62 miles would significantly aid Ukraine.
GLSDB missile bombs — an innovative solution from Sweden and the USA
GLSDB (Ground Launched Small Diameter Bomb) has been in development since 2015, initiated by Sweden to extend the range of M270 MLRS and M142 HIMARS multiple launch rocket systems, while keeping costs low.
The concept involves using the rocket engine of a GMLRS missile, combined with a GBU-39 SDB glide bomb. Utilizing existing solutions enables quick production and a lower cost compared to developing a new long-range system from scratch. The operation principle involves launching the missile bomb. Once the rocket engine burns out, it detaches, allowing the bomb to continue on its course to the target after unfolding its wings.
Firepower vs. precision — the eternal dilemma
Ukraine was the first user of this weapon, and after promising initial months, the GLSDB missile bombs became ineffective. This was due to disruptions in GPS navigation, the primary guidance system for SDB bombs, by systems like the R-330Zh Zhitel.
While the bombs are equipped with an inertial navigation module that calculates position based on factors like flight speed and time, these calculations can accumulate errors over distance. Consequently, the bomb's precision can degrade from a few feet to several hundred feet, depending on the distance.
Combined with a small warhead weighing 198 lbs, about 35 lbs of which is explosive material, this makes it ineffective if it deviates from the intended impact point. This issue is less pronounced with JDAM-ER bombs, particularly those weighing 992 lbs or 1984 lbs, where nearly half the weight is the explosive charge, or with MGM-140 ATACMS ballistic missiles. For these, lack of precision can be offset by firepower.
Unfortunately, details on how the Americans modified the GLSDB missile bombs remain unknown, and the secret might only be revealed if pictures of the wreckage appear online. One possibility could be the use of additional HOJ (Home-on-jam) seeker heads to guide the bomb to the source of interference.
