Saab To Fly First ‘Software-defined’ Fuselage

Later this year, Saab plans to fly a self-funded autonomous air vehicle that will be used as a testbed for some of its systems. More importantly, the vehicle will be the first aircraft to fly with a software-defined fuselage at the heart of its structure.

Working with Divergent Technologies, Saab has developed an autonomous vehicle approximately 5 meters long that comprises 26 3D-printed parts made using laser powder-fusion additive technology. Divergent has already built and supplied the vehicle's fuselage, and its load-bearing properties have been rigorously tested.

Software-defined hardware manufacturing is what Saab sees as a logical next step in aircraft design and production, and it builds on its extensive work in software-defined avionics and model-based engineering. Much of this work found its first major expression in the Gripen E fighter, which was created using computer-aided design (CAD) and model-based engineering. The resulting digital twin enables manufacturing using 3D digital models rather than traditional 2D paper drawings.

Additionally, the fighter’s avionics employ an architecture that segregates flight-critical software from mission systems in a computer hardware-independent arrangement. This allows rapid upgrades to mission systems without affecting flight-critical software.

Armed with this expertise, The Rainforest—Saab’s internal start-up for transformative innovation—began looking at how model-based engineering and software-defined avionics could be applied to aircraft manufacturing.

“We are asking ourselves the question. In the Gripen E, customers get a platform where they can code mission-critical applications in the morning and fly them in the afternoon. How can we give them the same level of software flexibility, but for actual hardware?” said Axel Bååthe, head of The Rainforest. “We call this software-defined hardware manufacturing.

“We envision that Saab’s future production factory is our most important product. We want to be able to give our customers freedom to not feel locked into a specific design, neither in hardware or software. The production factory will be one that reconfigures itself instantly to build whatever our joint digital twin looks like, without being limited by expensive investment in new tooling.”

“CAD in the morning, fly in the afternoon” is how Saab defines its new vision. Such an undertaking is ambitious and time-consuming, but as a first step, the concept of building load-carrying aerostructures in a more software-defined way was selected, for which a partner was required.

Saab selected Divergent Technologies, an additive manufacturing pioneer based in Torrance, California, that is already producing a range of parts for a variety of multi-domain applications. The company has ambitious plans, too, with a further five factories planned over the next two years, potentially including one in Europe.

Using digital design driven by artificial intelligence, topology-optimized structures can be created. Given a set of requirements, such as internal capacity and system requirements, the system can create a 3D structural design that is fully optimized to meet the needs while accounting for load paths, without the constraints imposed by traditional manufacturing and design methods.

Complex shapes such as lattices and intricate 3D curves become possible, freeing structural design from straight lines, perfect circles, welding, and riveting. Elements of the structure can be thickened or slimmed down according to the loads they will bear, and because the 3D model is purely digital, changes can be made—even outer mold line—and the whole design altered accordingly, all within the digital twin. The possibility of more complex structures also enables more efficient use of internal volume and the location of access apertures, wiring harnesses, and cabling.

As a result, the adoption of software-defined hardware and 3D printing greatly reduces the parts count, material waste, and manufacturing time. Moreover, each factory can produce an unlimited array of varying parts for different applications.

Divergent Technologies has also devised innovative fixtureless assembly technology that employs advanced robotics to position parts in a referenceless 3D space, ensuring a perfect fit during assembly. Details of the assembly system remain under wraps, but the promise is assembly facilities that do not require expensive fixed-alignment systems.