Asked whether the students benefited a lot from NLR’s expertise in composite materials, Sterk pointed out that the students already knew a lot themselves. “The big advantage is obviously that in our workshop they can ask us anything, because we have people working here who have loads of specialised knowledge and experience,” he says. Edward Everts of Solar Team Twente said: “At one point we found the pack had a leak, and Rémon and I were unable to find it. Senne walked around it and heard exactly where the hole was, even though it was really tiny.”
As NLR has been working alongside successive Twente Solar Teams since 2009, nothing much unexpected happens, not least because the students are now far more proficient in such matters as planning and the transfer of knowledge via the mentor system. But there are still some things that require that little bit of extra experience, says Sterk. This applies particularly to the structural design of the composite parts and how the design influences the production of those parts. During the conceptual phase there were several design sessions where the students could discuss their questions about composite structures with NLR. Different design options were examined and weighed up in terms of performance, material choice and incorporability. By way of example, he mentioned the fastening of the pedals to the chassis. The problem here lies in the use of different materials, such as metals, and drilling through the sheets. “It has to be as light as possible and it’s not wise simply to hammer a bolt through a sandwich sheet,” says Sterk.
Another recurring problem that crops up every two years is the ‘roll bar’: a frame that protects the driver if the car turns over. “The question that arises every time is: should we make it using composite materials or aluminium? As a roll bar made of composite has numerous consequences for the design, especially in terms of safety, we invariably decide not to use it,” says Sterk. “Often the design is unsuitable for integrating a safe and simple composite roll bar. The slightly heavier weight of an aluminium variant has a negligible effect on the car’s performance, because the aerodynamics are what really count. So the roll bar is again made of aluminium.” The composite work for the Twente team is not challenging for NLR, but it can lead to a student suddenly seeing something worthwhile in composite materials. Sterk was once himself a member of the Formula Student Race Team of Delft University of Technology, which is where he first came across composites. “It was only after that experience that I decided to get into composites!”