The United States is preparing to ship a new batch of long-range GLSDBs (Ground-Launched Small Diameter Bombs) for the M142 HIMARS and M270 MLRS missile systems to Ukraine. It should be noted that this is a combination of a jet engine from an M26 unguided rocket and a GBU-39/B SDB I precision glide bomb, with a maximum range of 150 km.
Reuters reports on the successful work on the GLSDB, citing its sources and noting that the main drawback — the vulnerability of the satellite navigation system to electronic warfare — has been addressed. In addition, the internal elements of the ammunition were improved to increase its stability. This likely points to changes in the design of the special adapter between the engine and the bomb, which also appears to have had issues.
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In recent weeks, 19 GLSDBs have been used and proved to be effective. A shipment of this ammunition is already in Europe, meaning it can be transferred to Ukraine very soon.
On behalf of Defense Express, We would like to remind you that GLSDBs have become an example of a weapon whose expectations vastly exceeded its actual impact on the battlefield. Especially given that their transfer to Ukraine was announced back in February 2023 as part of a $2.175 billion aid package. At that time, GLSDBs were ordered under the USAID program, which involves ordering weapons directly from manufacturers.
They arrived in Ukraine in early 2024, a year later. In particular, the first wreckage of the GBU-39/B Small Diameter Bomb was shown by russians in mid-February. In April, U.S. Deputy Secretary of Defense Bill LaPlante, while not directly naming the weapon, pointed to the GLSDB as an example of a system that failed on the battlefield.
Obviously, the failure to fulfill the contract for Boeing and Saab, which jointly developed the GLSDB, is unacceptable, especially since their development proved ineffective and required additional work. Ultimately, it is not only a matter of fulfilling the current order, but also of potential contracts and reputation.
In the end, the question remains as to what changes were made to the GBU-39/B SDB guidance system, as the installation of a new jamming-resistant satellite navigation system is only one possible solution. It should be understood that the principle of using the GLSDB, which involves ascending to a significant altitude, exposes it to electronic warfare (EW) for a considerable amount of time. This explains why the GLSDB is critically affected by electronic warfare, while the SDB from aircraft is less vulnerable.
Another option is to reconsider the concept of using the system and use the SDB with a semi-active laser guidance. This requires target illumination with a laser, for example, from a UAV. However, it is not easily suppressed by electronic warfare and allows for hitting moving targets. It should be understood that the entire effectiveness of the SDB, which weighs 129 kg, depends on the accuracy of the shot, which must be within a few meters.
Earlier Defense Express reported that Sikorsky had created brand-new aircraft type with revolutionary efficiency exceeding convertiplane.
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