The Swedish BK M90 is an aircraft launched stand-off cluster munition developed in the 1990s by Daimler-Chrysler Aerospace in Germany under “DWS-24” for Dispenser Weapon System 24 barrel. It was designed to be used by the Saab JAS 39 Gripen and retrofitted to the Saab 37 Viggen, to deliver two different types of submunitions, being anti-personnel and anti-tank munitions. As it is designed as a stand-off weapon, which allows the aircraft to release the dispenser at a safe distance from the target, reducing the risk of detection to enemy air defenses.
(AJS37 with 4 BK-90 pods)
Key Points in the Development of the BK M90:
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Background and Design: The BK M90 was developed as part of Sweden’s efforts to modernize its military capabilities in the post-Cold War era. The weapon is based on the German DWS-24, a cluster munition system, built by Daimler-Chrysler aerospace. It was intended to provide the Flygvapnet with an effective way to target multiple objectives over a wide area.The BK M90 is a GPS and inertial guided glide munition, meaning it does not have a propulsion system, but it glides towards its target after release. These precision navigation system allow for accurate targeting even in adverse weather conditions.
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Submunitions: The BK M90 can carry two different types of submunitions, a total of 72-144 munitions, including:
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MJ1: Armor-penetrating bomblets, designed to target vehicles and armored personnel carriers.
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MJ2: Anti-personnel submunitions, which are designed to cover a large area to maximize their effectiveness against enemy infantry.
These submunitions are dispersed over a wide area as the dispenser glides over the target zone, creating a swath of coverage that increased the likelihood of hitting personnel as well as vehicles.
(Operation of dispensary)
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Operational Role: The BK M90 was developed for use in situations where the Flygvapnet needs to quickly disable and destroy enemy ground forces, specifically in situations where there is a mixture of personnel and light to medium armored vehicles. The ability to release the weapon from a distance with preset or set an waypoint in the cockpit enhances the survivability of the aircraft and its crew in contested airspace.
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Service History: The BK M90 entered service in the 1990s and has been integrated into the arsenal of the Flygvapnet. It has been exported to Greece, who still operates it, however it hasn’t been used in combat to date, but it remains a key component of Sweden’s air-to-ground capability and tactical history, particularly for defensive operations. Sweden’s defense strategy, which has historically emphasized self-reliance and preparedness for defending its territory, made the BK M90 was an important part of the Flygvapnet’s tools for deterring invasions or large-scale ground attacks.
(Gripen Sporting two BK M90 pods on the inmost pylons, supposedly the only two set to carry them)
- International Law: In 2008 global concerns with cluster weapons over the long-term risks of unexploded munitions left on battlefields around the world. Unexploded submunitions can remain a civilian hazard for years, as a result, many countries signed the 2008 Convention on Cluster Munitions. Sweden agreed to sign the treaty in 2008, which pulled the BK M90 from Swedish service and arsenal.
Another system in the BK M90 is in the submunitions themselves, where the “Cluster bombs” are notorious for leaving active explosive ordnance which failed to detonate or engage upon impact, and for that reason all weapons using sub-munitions for a long time were rejected by the Försvarets Materielverk Defence Materiel Administration deeming it a risk not worth taking.
The very technologically advanced system in the cluster munitions themselves, a system which assigned each individual munition a launch designation code; under the case the munition was not to explode or not be “cleared for launch” (I.e: the Code isn’t active) would stop the munition from entering “kill mode” and keep unintentional targets safe. While this is mildly classified, it is a segment in the “ELECTRONIC” segment in the FMV manual, which goes over all the electric systems in the BK M90’s housing.
Overall, the BK M90 was a well planned and thought out design that reflects Sweden’s strategic needs during the 1990s, mainly that of maintaining the iron curtain, able to deploy across the Swedish Finnish border in a matter of hours. Despite the UN’s CCM, it contributed as an important development step in Swedish weapons tech history.
(BK M90 on a loading trolley)
1. Technical Specifications:
- Weight: Approximately 600 kg (1,320 lbs)
- Length: 2.5 meters (8.2 feet)
- Range: The BK-90 is a glide bomb, meaning it has no propulsion system of its own. Its effective range depends on the release altitude and speed of the launching aircraft, with an estimated range of 5-10 km when released at medium altitude.
- Submunitions: The BK M90 can carry either a mix of armor-piercing and anti-personnel submunitions or a purely anti-personnel configuration. Each dispenser typically carries:
- MJ1 Bomblets: Armor-piercing submunitions (used to target light to medium armored vehicles).
- MJ2 Bomblets: Anti-personnel bomblets (designed to cover a wide area).
- Bomblet Capacity: The BK M90 typically carries between 72 to 144 submunitions, depending on the type and loadout.
(The MJ1 & MJ2 submunition type)
2. Guidance System:
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The BK M90 uses inertial guidance with possible GPS updates for precision. This ensures that the weapon can be deployed accurately even in adverse weather or poor visibility.
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CEP (Circular Error Probability): Though exact figures are not always available, it is likely that the BK M90’s CEP (which measures accuracy) would be in the range of 30-50 meters. This makes it relatively precise for a cluster munition but not as accurate as modern laser or TV guided bombs or missiles.
(This graphic shows the intertial guidance system, and how it would function)
3. Operational Statistics:
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Deployment Platforms: The BK M90 is compatible with the Saab JAS 39 Gripen and Saab AJS37 Viggen aircraft. The Gripen is the would-be primary platform for the BK M90 today, with around 130+ Gripens in service with the Swedish Air Force.
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Flight Altitude: The BK M90 can be released from low to medium altitudes, typically in the range of 100 to 10,000 meters (330 to 33,000 feet), depending on the situation.
(The schematic of the construction and moving parts of the BK M90)
4. Sweden’s Defense Budget and Air Force:
During the period of the BK M90’s development in the late 1980s and early 1990s, Sweden maintained a defense budget of approximately 2-2.5% of its GDP, translating to around $4-5 billion USD annually. The Flygvapnet focused on maintaining an independent & technologically advanced air defense system, with large investments in indigenous platforms like the Gripen and advanced weapons systems such as the BK M90.
5. Cluster Munitions and Humanitarian Impact:
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Failure Rate of Submunitions: Like many cluster munitions, the BK M90’s submunitions have a small but significant dud rate. This means that some bomblets may fail to detonate upon impact, potentially becoming hazardous unexploded ordnance. The average failure rate for similar systems is around 2-10%, though this can vary based on environmental conditions, altitude of deployment, and the condition of the munitions themselves.
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Estimated Impact Radius: The BK M90 disperses its submunitions over an area typically measuring 200 to 400 meters in diameter, depending on the altitude, speed, and mode of deployment. This wide dispersal increases the likelihood of hitting multiple targets but also increases the risk of collateral damage.
(This graphic shows the rectangular cluster release mode, and the glide path of a single unit, multiple could be used in tandem to create a “alley” of mines)
6. Sweden and the Convention on Cluster Munitions:
Sweden signed the Convention on Cluster Munitions in 2008, joining the global effort to eliminate the use and production of these weapons due to their long-term humanitarian risks. However, before signing the treaty, Sweden maintained a significant stockpile of cluster munitions, including the BK M90. The convention required the destruction of stockpiled munitions, though the extent of Sweden’s compliance in terms of specific numbers has not been widely disclosed.
(BK M90 mounted to a Gripen, seems to be shown in a museum or private hangar)
THE FMV BK M90 manual (Declass)
This manual goes over the guidance, electrical, radar, release, data analysis, components, and use case situations. There is much more in depth parts that some Swedish speaking forum members could read and explain for others who would like to know more. I might work on translating it.
00 INTRODUCTION AND COURSE OF OPERATION
10 HULL AND CONTENTS PARTS
20 STEERING, CONTROL AND NAVIGATION SYSTEMS
30 STEERING, CONTROL AND NAVIGATION SYSTEMS
70 SYSTEM OF EFFECT
81 ELECTRICAL POWER SYSTEM
92 BASIC EQUIPMENT
ATTACHMENTS
- Yes
- Yes, but in Air RB & Air Sim only
- No
This is also a Video I found on that shows it being tested and mounted on a Gripen in its “aerodynamic testing” phase to make sure it was safe for aircraft use.
Secondary Sources
Stand off submunition dispenser Mjölner, BK90 (Archived old web source)
EADS/Bofors DWS-39 (Archived old web source)