GLSDB On The Way To Ukraine

Reuters reported in late November 2022 that the Pentagon was considering sending Ukraine the GLSDB weapon.

Then on 20 January 2023 the Telegram channel Ukraine War — Intel News included GLSDB on the extensive list of weapons Ukraine was expecting over the coming weeks.

If correct, GLSDB could well be a game changer in much the same way as HIMARS was.

Ground Launched Small Diameter Bombs (GLSDB) are relatively cheap and capable of being used in existing Ukraine rocket launch platforms such as HIMARS.

GLSDB would allow Zelensky’s troops “to strike far behind Russian lines as the West struggles to meet demand for more arms,” Reuters wrote.

SAAB developed GLSDB in partnership with Boeing. SAAB describes the GPS-guided GLSDB as highly effective with the capability of being engaged from any angle and usable in all weather conditions.

What is the GLSDB?

The Ground Launched Small Diameter Bomb is a precision-guided munition that is designed to be launched from ground-based platforms, such as the M270 Multiple Launch Rocket System and HIMARS.

The missile made by Boeing and the Saab Group, who modified Boeing’s GBU-39 Small Diameter Bomb (SDB) with the addition of a rocket motor.

The weapon is intended to provide a highly accurate and reliable means of engaging a wide range of targets, including stationary and moving vehicles, buildings, and other fortified structures. Even ships.

One of the key features of the GLSDB is its small diameter offering a small radar cross section. This allows the weapon to evade enemy radar and other detection systems, making it difficult for the enemy to detect and intercept.

After the rocket motor launches it to a high enough altitude and speed, the wings deploy and glide the bomb to its target. While typical rockets from multiple launch rocket systems (MLRS) follow a ballistic trajectory, the rocket-launched SDB can be launched to altitude and glide on a selected trajectory. The SDB and rocket motor separate at altitude.

I could find no information on glide speed — this would be important in establishing the likelihood of the SDB being successfully intercepted with high probability by Russian air defences. The HIMARS standard MLRS rockets have a maximum flight speed of Mach 2.4. Bear in mind that these bombs were designed for unassisted air launch, so my guess is that they fly subsonic in glide mode.

The GLSDB is guided by a combination of inertial navigation and GPS, which allows it to fly to its target with a high degree of accuracy. The weapon is also equipped with a semi-active laser seeker, which allows it to home in on its target even in the presence of countermeasures such as flares or smoke. This makes the GLSDB highly effective against moving targets, such as vehicles or boats.

There are several warhead payloads. The smallest is in the SDB1 bomb (GBU-39B) with a 16 kg high-explosive enhanced blast warhead. The warhead is also equipped with a delay fuse, which allows it to penetrate a target before detonating, increasing the effectiveness of the weapon against hardened structures. Warhead penetration is 3 ft (1 m) of steel reinforced concrete under 3 ft of earth.

In a 2017 demonstration, the GLSDB engaged a moving target at a distance of 62 mi (100 km). The [small diameter bomb] SDB and rocket motor separated at altitude and the bomb used a semi-active laser (SAL) seeker to track and engage the target. A 2019 test extended this range to 81 mi (130 km) against a target at sea.

It is being considered for use in Ukraine with the HIMARS system. Ukraine has long wanted the ATACMS missiles for their long range. The GLSDB would be a compromise giving them a range of some 150 kilometres (94 miles) using a M26 rocket engine and an SDB. Both the SDB and the M26 are common in the US arsenal. It could be delivered by early 2023 using surplus bombs from the conflict in Afghanistan. Each would cost US$40,000. — Wikipedia

To the cost of the bomb must be added that of the relatively cheap solid fuel rocket motor. Compare that with the price per unit for ATACMS which is estimated to be well over $1M. The US has many SDBs in its arsenal and the rocket motors are said to be plentiful.

I checked into costings and $40,000 seemed a bit on the low side for the GBU-39, with costs ~$100,000 per unit for the perhaps being more realistic:

April 2016 — FMS request by Australia for 2,950 units and support equipment valued at US$386 million (Wikipedia ibid.).

However Air Force quotes $40,000.

Whichever way, they offer many more bangs per buck than the ATACMS, albeit with shorter range.

Why could GLSDB be a game changer?

The GLSDB offers high-lethality, increased range and high-manoeuvrability. It has the ability to defeat soft and hard skin threats, targets behind the launcher, as well as hard-to-reach targets. That includes terrain avoidance, cave breaching and reverse-slope engagement.

The GLSDB can reach a range of up to 130km (81 nm) although some reports claim 150 km. It has the ability to hit moving targets under all weather conditions both during the day and at night, with low collateral damage due to its high precision guidance. The CEP is 5–8 metres (SDB1)

According to Telegram Channel United24Media:

OSINT analyst Def Mon calculated the effective range of GLSDB missiles [see map below]

If Ukraine gets these missiles, the situation at the front will change very well.

Thus, the Armed Forces of Ukraine will be able to reach targets on the territory of the entire mainland of occupied Ukraine, and will also be able to hit the north of Crimea and the border territory of Russia itself.

In the above image the red line is the front — the Russian line of control as of the day of calculation. The blue dashed line is 140 km from the front.

Here’s an expert view (Former Commanding General US Army Europe):

The decision

In late 2022 the US rejected Ukraine’s request for the ATACMS missile which can be fired from the HIMARS platform. There was concern that the 300 km range of ATACMS would enable Ukraine to hit targets deep within Russian territory and that would cause escalation. The current M31 GMLRS missile that Ukraine uses in its HIMARS launchers has a range of up to 70 km.

So, the range of the GLSDB falls neatly in between that of the M31 and the ATACMS.

It brings targets in Crimea into range, although not Sevastopol, based on the current front line (and there would be some safety margin allowed for the launchers).

Should Russian forces be worried?

I think that the answer to this depends on how effective Russian air defences would be against the weapon in glide mode. Having a longer range than the standard HIMARS MLRS rockets, there is more time for acquisition and interception, especially if the glide mode is subsonic.

From a morale point of view, this is certain to have a negative effect on Russian forces. There is ample evidence to deomonstrate that HIMARS had a huge negative effect on Russian force morale.

Logistically it could pose additional problems. The standard HIMARS MLRS rocket has had a serious impact on Russian arms dumps dispositions and structure.

HIMARS attacks by Ukraine have been credited with “destroy[ing] Russian command nodes, tens of thousands of howitzer artillery rounds and a staggering 20 million small-arms rounds.” — Wikipedia (ibid.)

With Russia already suffering big problems in supplying sufficient ammunition for their traditional artillery-driven battle tactics, things can only get worse for them.

Should the West be worried?

Politically, Putin has said that weapons which threaten Russian territory would lead to escalation. He considers Crimea, Lukhansk and Donetsk to be Russian territory.

Here’s the latest pot-stirring as the first full year of the war draws near:

Continued deliveries of arms to Ukraine by its allies in the West will lead to retaliation with “more powerful weapons,” a top official in Russian President Vladimir Putin’s regime said on Sunday.

Vyacheslav Volodin, chairman of Russia’s lower house, the State Duma, threatened Europe and the U.S. with “global catastrophe” over their continued military support to the government in Kyiv, which is trying to continue retaking territory it lost in the Russian invasion.

Volodin directly invoked the use of nuclear weapons in his statement over messaging app Telegram. — politico.eu

There's plenty of food for thought in that, since reiterated by Russian ex-President Medvedev, one of Putin's running dogs:

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Canonical link: This story was first published in Medium on 24 January 2023 [edited]