RBS15 – on the road to the Next Generation

“Psychedelic” is the word I hear someone standing next to me use to describe the room. I agree. We are standing inside what is roughly a 13 m long cube, with all the surfaces being covered with soft blue spikes of different sizes. The room is completely void of echoes, and they say that if you stand here alone, you will eventually hear your heart beating. Loudly. The only objects standing out is a large frame mounted halfway up one wall, and a pattern of blank discs mounted opposite the frame, these being the flight motion simulator and the antenna wall respectively.  We are in the anechoic chamber at ELSI, and I almost expect GLaDOS to start talking to us.

ELSI, or the Electrical Warfare Simulator, is at the hearth of Saab’s anti-ship missile program. The seeker-head of the RBS15 missile is mounted on the flight motion simulator, which moves the seeker in 3-axises as it ‘flies’. On the other end of the room the antennas sends out signals corresponding to what the seeker would see at any given moment during its course. This includes not only target signatures, environmental effects, and countermeasures in the form of false targets and active jammers. All this, coupled with the seekers simulated position and real-world direction, are then used to create the model, which is fed to the antenna wall’s signal generator which creates artificial radar returns for the seeker head. As noted, it is very much a case of the actual hardware being in the loop during testing.

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RBS15, sporting a 200 kilogram warhead to dissuade enemy ships from getting within 200 kilometers of your waters. Source: Own picture

The story of ELSI goes back to the early 90’s, when the board decided upon the investment, partly to ensure that Saab would be able to expand their share of the export market in an age of shrinking defence budgets. 1994 the site was running its first tests, and four years later it was operating at the desired level, a host of teething problems having been fixed.

Finland is no stranger to the RBS15, having operated the first generation of the missile from ship and shorebased batteries under the local designation MTO-85 since the late eighties. As such, a Finnish delegation visited ELSI early on in 1999, with the latest Finnish threat pictures. The purpose was to run a comprehensive round of tests with the MTO-85 seeker, which then provided the basis for an upgrade program launched at Saab. The upgraded seeker was then run through the same set of tests the following year. The tests can’t have gone too bad, as two years later the upgraded RBS15 SFIII, a customised RBS15 MkII, was introduced in Finnish service as the MTO 85M.

Now the RBS15 is a hot topic again for Finland. The anti-ship missile is one of the candidates for the PTO2020-program, the current acquisition to replace the MTO 85M on the Hamina-class following their ongoing MLU and in the truckmounted batteries, as well as becoming the main surface-to-surface weapon for the new Pohjanmaa-class corvettes (Squadron 2020). And Saab is confident that the RBS15 will be a prime candidate this time as well.

Saab has two distinct versions on the table. Noting that the baseline version was nearing the end of its life, Saab embarked on an ambitious upgrade program. While the step from MkI to MkII was an upgrade, the Mk3 was a radical redesign resulting in what was basically a completely new missile. Following a four-year test program it was adopted by the German Navy, and shortly after that by the Poles. The Swedish Navy is still soldiering on with the MkII, and would have been happy to adopt the Mk3. However, the Swedish Air Force had other thoughts, and had a requirement for the weapon to be lighter to allow four missiles to be carried simultaneously by the upcoming 39E Gripen. The result was the RBS15 ‘Next Generation’ (still lacking an official designation, though Mk4 wouldn’t come as a surprise), which is an upgraded Mk3 with a lighter launch weight, longer range, and generally improved performance. The weapon is contracted for introduction into Swedish service for both the Navy and the Air Force during the next decade, and Saab doesn’t mince words: “It is the most capable and advanced anti-ship missile on the market”, as was explained to us during a briefing.

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The new launch tubes for the RBS15 Mk3 are seemingly of a more complex shape than the older ones, but under the surface ease of manufacture actually means they are cheaper. Source: Own picture

The new launchers are a chapter for themselves, with the original box-like launcher having been replaced by octagonal tubes. The reason behind this is cost-savings, as the original box held the missile tilted 45° to one side, meaning that the railings holding the missile inside the box have very demanding tolerances. The newer launch tube instead holds the missile level, which is somewhat more forgiving on the structures. But it in turn leads to new questions. “The Visby-class will fit the NG, but we have already cut square holes in the side for the MkII, so in that case we will use the old launcher,” a technical sales support engineer explained. “The missile itself doesn’t really care, it can handle both positions.”

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The humble MSU (Missile switching unit) is the only major piece of hardware except the launch container that is needed aboard a vessel to be able to fire RBS15. Source: Own picture

What then is so special about the RBS15? From a Finnish standpoint, the Baltic Sea as the design environment of choice is interesting. The often poor weather combined with a cluttered archipelago and lots of civilian traffic makes for a challenging battlefield, and Saab is one of very few companies designing their anti-ship missiles from the outset for littoral waters as opposed to the open sea. This is also where ELSI comes into play. allowing for advanced simulations of the performance of the seeker, something which plays a key role in evaluating parameters such as ECCM and target discrimination. The weapon is also capable of performing the land-attack role against ‘soft’ targets, though it is not optimised for the role in the same way as ‘true’ land-attack cruise missiles.

The ships we are firing against are not that keen on being hit.

The flight path of the missile is guided through a number of pre-set 3D waypoints, and the missile then navigates using both GPS and inertial navigation to make sure it hits all waypoints on time. Timing is key for features such as simultaneous time-on-target, a default feature for the RBS15, and as such the missile will throttle up and down in flight as needed to hit all waypoints on the exact time given. The exact height of the sea-skimming part of the trajectory also varies according to sea state, with larger waves naturally forcing the missile to fly at higher altitude. And in case the missile misses its target, it will swing around and do a reattack. If no target is found at all, it will eventually head off to a pre-set destruction point, which can be altered by the operator to make sure the missile doesn’t fly off and self-destruct over the nearest town.

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Saab’s technology demonstrator 39-7 displaying the capability to carry two RBS15 under each wing, giving a four-ship of Gripen E an almost unrivalled firepower against enemy shipping. A full salvo will be devastating against enemy warships, but also comes at a hefty price. Picture courtesy of Saab Ab

For PTO2020, Saab hasn’t offered a specific variant, but instead opened the shop and described the Mk3 available today and the NG available tomorrow. The systems will also be interoperable, with NG launchers able to fire Mk3 and Mk3 launchers able (after a software update) to launch NG missiles. Customisation, as has been the case with the earlier Finnish versions, is also an option, but Saab notes that less and less countries are willing to pay the premium of having a customised missile. From a Finnish perspective, the supply chain is interesting. Diehl in Germany handles final assembly, with Saab building many major subassemblies and handling much of the development work and testing in Linköping. However, a new location on the map is Saab’s brand new technology centre, the STC, in Tampere, which is heavily involved in the electronic warfare side of the technology for the RBS15 NG.

The first draft of the text and pictures has been provided to Saab for screening to ensure that no classified, export controlled, or company confidential information is included.

One thought on “RBS15 – on the road to the Next Generation

  1. Pingback: 9LV offered for Squadron 2020 – Corporal Frisk

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