Skip to main content: Austrian national luge team – In search of thousandths of a second

Austrian national luge teamIn search of thousandths of a second

Austria's national luge team will be racing down the ice track on brand new sleds this winter. With the new design, the athletes hope to gain precious thousandths of a second on the competition. The basis for the new sled was a 3D scan from 1zu1 Prototypes. Marco Hermann and Hubert Kemmer (1zu1) and Rainer Nachbaur (Differences) provide some insights into the project.

27. November 2014

The blink of an eye lasts a tenth of a second. In the winter sport of luge, this is practically an eternity. Hurtling downhill at speeds of up to 130 km/h over a distance of more than one kilometer, the time gap between the competitors is often just a few thousandths of a second. Which makes it all the more surprising that the athletes used to make their sleds by hand. In other words: No two sleds were identical. They would take their unique specimens to the ice track, compare their riding characteristics and speed, and then go away and improve them some more.



The Hohenems-based ski manufacturer Differences is now working together with the Austrian national team to take sled development to a completely new level. For the first time, the sleds have become truly reproducible, which means they can be improved on a step-by-step basis. Their designer is a natural-born inventor and tinkerer: Rainer Nachbaur is CEO of the ski manufacturer Differences, based in Vorarlberg. The design data for the sleds was provided by measurement technician Marco Hermann at 1zu1 Prototypes. Hubert Kemmer, internal sales manager, took care of the customer service aspect.


Mr. Nachbaur, how did your work for the Austrian Luge Federation come about?

Rainer Nachbaur: I talked to the person responsible at an event in autumn 2013 and we immediately discussed possible improvements in terms of development. We've been producing very high quality skis for more than ten years, all of them unique. As a result, we know a lot about riding characteristics, damping, dynamics and acceleration under extreme loads. In addition, we can combine composite plastics with various materials such as wood, steel, aluminum or rubber, which aren't a natural fit for each other in terms of the material properties.

After the end of the Olympic season, the Luge Federation approached me and we started the project. The first step was to completely re-engineer the existing equipment. We wanted to base the development process on a clean 3D design.

So you had one of the previous luge sleds scanned. Why was 1zu1 Prototypes the right partner for this?

Rainer Nachbaur: We've worked together many times before. They simply understand very well what I need and, above all, how I need it. It is not just about the quality of the scan. 1to1 Prototypes knows how to prepare the 3D data so that I can process it immediately.

Hubert Kemmer: Rainer Nachbaur approached us in May, and two weeks later we already had the sled in the 3D scanner. We always take a close look at how the customer wants their data prepared. This can save them countless hours of post-processing.

Can you make this process intelligible to a layperson?

Hubert Kemmer (laughs): I'll try! In 3D scanning, an image is first created from millions of individual pixels – like a photo from a digital camera. In the next step, from these individual points the software extrapolates a mesh consisting of millions of polygons, which describes the object's surface. The finer the mesh, the more accurate the data model, but also the greater the amount of data required.

The third step is to create a CAD design based on the model. For example, the polygon mesh still shows many small irregularities. The designer then determines where there should be a completely flat surface, where a curvature should begin and with what radius it should extend. This can only be done by hand. Then you need to know how the customer wants the data to be prepared.

You don't get a luge sled in the lab every day.

Marco Hermann: 90 percent of our work involves injection-molded parts that we've produced in-house at 1zu1 Prototypes. They are precisely measured in the 3D scanner and the customer receives an initial sample inspection report upon request. However, we frequently get sent some very unusual items. We've already had a Christmas stollen (fruit loaf) in the 3D scanner as well as artists' sculptures and even a brain. Not a real one, thank goodness, one made of plastic.

Were there any particular challenges in this project?

Marco Hermann: Our scanner can record a field of 560 by 560 millimeters in one pass. If the object is larger, we apply so-called reference points to it. These are recognized by the software and the individual scans are then aligned at these points and joined together very precisely – similar to a panorama photo on a smartphone. This allows us to scan objects of virtually any size – in theory, even a car or a plane.

We can also only scan the parts that are visible to the eye. We had to measure the curvature of the shell, into which the feet are inserted, using a device known as a feeler. Although this has a similar degree of accuracy, it only creates individual measuring points instead of a complete image of the surface, as with 3D scanning. However, this particular surface is easy to reconstruct as we've already recorded the entire external surface and we know the material thickness.

How did the project progress?

Rainer Nachbaur: The plan was firstly to rebuild the old sled largely unchanged, so that we would have the same starting point as before, but in a reproducible form. Naturally, we also took some minor requests by the athletes into account. We adapted the shape slightly so that the feet lie better and have more grip for steering.

Then we made the master model, a wooden mold to which the composite material for the shell is applied. For the first sled, the athletes specified far too much stiffness. We gradually reduced this until it was time for the first test in Lillehammer at the end of September.

That was a really exciting moment. How did it run on the ice track?

Rainer Nachbaur: The athletes were understandably skeptical at first. After all, this was the first time they'd ever departed from their tried-and-tested way of racing. However, after the first test rides it was already clear that we were on the right track, and within a week the previous year's models were finally sat gathering dust.

In the past, each sled was a unique, handmade piece with individual riding characteristics. Now we can at last develop them in a professional manner by improving the existing model step by step. The athletes visited us almost every week, telling us how the sled reacted to bumps, how the steering felt. This allowed us to define the next development step in each case.

To what extent can these development steps still be based on calculations? Or do you trust your instincts here?

Rainer Nachbaur: A lot can be calculated. But for those crucial finer points, you also trust your gut. We can draw on our know-how from more than ten years of ski manufacture, and the athletes can bring their own experiences to the table. After all, they had previously made their sleds themselves by hand – and ridden them to the top of the world rankings.

Hubert Kemmer: For me, this project is a prime example of the professional interaction of different partners within a development process. 1zu1 Prototypes delivered the database in this case, Rainer Nachbaur carried out the development and involved the athletes to perfection. In other projects we can support the development engineers on the customer side with our expertise in different manufacturing processes. It is always important that the knowledge and experience of all participants flow together to create an optimal solution.

Final question: Would you dare to test one of these luge sleds yourself?

Marco Hermann: Of course! That would certainly be exciting, but also very cool. Hubert Kemmer: I would trust the technology. But the idea of lying on one of these sleds and thundering down the ice track would make my stomach churn ... Rainer Nachbaur: I've already ridden in a bobsled once. You're really just a passenger; you can only hope and pray you'll make it to the finish line in one piece. I imagine riding on a luge sled would be much worse – lying on my back while zooming down the ice track at 130 km/h. But I will definitely give it a try – at the latest next year when we start work on the two-seater.
 


Interviewed: Marco Hermann/1zu1 GOM metrology, Hubert Kemmer/head of internal sales at 1zu1 and Rainer Nachbaur/Differences. The interview was conducted by Wolfgang Pendl.

Copyright photos: Darko Todorovic (photos 2–9), Dominic Marsano (photo 1 and 10)


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