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SLWT production

The lightweight torpedo that’s a profound success

5 min read

The story behind the successful, on-time development of Saab’s Lightweight Torpedo is one of teamwork, engagement and trust, where the project’s organisation has been as innovative as the technology itself. Jörgen Thörnström and David Rönnberg explain more.

Saab’s new Lightweight Torpedo (SLWT), is a vital project for both Saab and its customers, in terms of investment and technological development. But it’s also been a transformative project for Saab’s internal processes.

The seeds of the project were sown in 2015. The current torpedo generation, the Torpedo 45, has been in service since the mid-1990s, with a gradual series of updates. However, as European regional threats grow, while technological complexities increase and the number of integration platforms multiply, there’s been a clear need for a brand-new torpedo system. Enter the SLWT, which the Swedish Navy refers to as Torpedo 47.

Why the new torpedo was needed

“The current lightweight torpedo has served our customers well for many years, but as we began to foresee difficulties maintaining the system, the question was: ‘How long can it last?’,” says Jörgen Thörnström, originally the Product Manager for SLWT’s production, but now the Head of Production at the Linköping and Motala sites for the Saab Dynamics business area. He’s the man who will oversee serial production of the torpedo for the next five years.

Saab's team preparing the lightweight torpedo for launch.

“The SLWT is necessary for both the customers (currently the Swedish and Finnish navies) and our company,” adds David Rönnberg, who is the head of the production project office and sits on the project steering group.

“We need to respond to technological changes and to new customer requirements..."
Jörgen Thörnström, Head of Production

“We need to respond to technological changes and to new customer requirements, but we also need to keep the skills base up at Saab because the experts who worked on the Torpedo 45 are getting older and even starting to retire. You could say that the new torpedo is a win-win for the customer and for Saab,” he says.

Key features of the new torpedo

Underwater image of Saab's lightweight torpedo.

Rönnberg adds that the main challenge in the development of the new Saab Lightweight Torpedo was to come up with a torpedo that was suited to the waters of the Stockholm Archipelago and the Baltic Sea, where the depths are relatively shallow and challenging in terms of hydro-acoustics. Another important consideration was the need to make the torpedo a generic and adaptable weapon for different platforms, such as surface vessels, helicopters and submarines.


Torpedo journey

Explore the capabilities of SLWT in detail.

View infographic

“The new SLWT has a state-of-the-art propulsion system and a new energy system which means it can travel through the water silently, making it much harder to detect,” says Jörgen Thörnström. “It also has a much better homing system for target seeking. Overall, it’s a major step forward in torpedo development.”

Success factors of SLWT project management

For Saab, it’s not only the product which is innovative. The way this project has been managed, with Jörgen and his project management colleague Stefan Melin taking a more integrated approach, has also been a real breakthrough. One of the main success factors was the cross-functional involvement from the outset.

“In previous projects we have often followed processes one after the other, but in this project we were all working together from day one, often with daily and sometimes twice-daily project meetings,” says David Rönnberg.

Well over 100 people are or have been, working on the SLWT project - designers, system engineers, electronic designers, mechanical designers, quality engineers, production engineers, operators, hydro-acoustic experts, procurement agents, logistics support and project leaders: by integrating these functions Saab could take a more joined-up approach, saving time later in the project.

Saab's lightweight torpedo team at production facilities.

“We involved the production and integrated logistics support functions side from the start, during the design concept phase. We undertook a study and spent a lot of time on site and in working groups with the customer, discussing the equipment they use today and how they use it, as well as what changes they wanted to have,” says Jörgen Thörnström.

“So from that process we gained a lot of insights into how they used the equipment and new thoughts on what we had to improve for the new torpedo. That was very good to have so early in the process,” he says.

A by-product of this diagnostic and prescriptive approach is that it has given the relationship with the customers in Sweden and Finland a real boost.

"Both the customers and ourselves have been very transparent with each other throughout the project..."
Jörgen Thörnström, Head of Production

“It’s a question of trust,” says Rönnberg. “Both the customers and ourselves have been very transparent with each other throughout the project, about what’s good and what’s not working so well. Not all customers want to have that level of openness but this was very good.”

Teamwork, engagement, trust and…a lot of fun!

With successful prototyping of the different phases of the project, that showed the customers that Saab backed up its talk with action, even the pandemic couldn’t put the team off its timetable. Serial production of the SLWT has now begun, as well as deliveries to the Swedish Navy.


For both David Rönnberg and Jörgen Thörnström, teamwork, engagement and trust have been cornerstones of this project. But, adds Rönnberg, one other ingredient has also been vital to this success story: fun!

“Seen from the steering group side, it seems to me that everyone is really enjoying the whole process and there’s a great relationship with the customer, which makes meetings with them much more fun too,” says Rönnberg.

“We have come much closer to the customers, particularly the Swedish customer, during this project. And that feeling is spreading to other projects as well. In the underwater business area, we are now much closer to the customer than we were before.”