After four years of studying bobsled and skeleton construction at ETH Zurich as part of the Citius Project, the International Bobsleigh and Skeleton Federation (IBSF) Vice President for Sport asked me if I wanted to apply to be a materials inspector for the IBSF. I said, “Yes,” of course and found myself working as a materials inspector at the 2018 Winter Olympics in South Korea. The materials inspectors verify that the bobsleds are prepared for the run according to regulations.
On race day, my fellow inspectors, Dragos Panaitescu (ROU) and Hermann Gigacher (AUT), and I met for breakfast at 7:30 in the morning and then quickly headed over to the bobsled run above the launch area to be present at training. There, our team provided information on technical aspects as well as details of the timing of runner control to the Olympic teams. The mere presence of materials inspectors indicated clearly that everything was carried out according to the regulations.
The only bobsled runners deployed on the track were those certified by the official IBSF materials inspectors. The respective tests looked at geometrical form and dimensions, the alloy of the runner’s material and its hardness. The alloy elements were checked using a handheld X-ray apparatus. Various measurements were taken within a few seconds for a reproducible result. We saved all measurements for possible referral and further processing later. If all measurements were within the regulations, the runners received a vignette, similar to a motorway toll vignette.
The runner inspection process filled our afternoon. We were grateful to have just enough time to pack up the material in the car and head over to the men’s two-man race. At 18:15 we returned to the launch area to get ready for the race with just enough time for a quick pre-race snack.
Before the race, the bobsleds were staged in a designated area: the “parc”. They were prepared in such a way that the runners could be attached as late as possible. Teams were required to finish-up work on their bobsleds 45 minutes before the race and during this time the so-called “parc fermé” remained closed. Only the jury, the materials inspectors, and assigned helpers were allowed to remain in the park. It was during this time that the first inspections of the race began.
The first thing that we checked were whether all of the runners had a valid vignette. Then came the runner radius. Several years ago, people raced with as narrow of a radius as possible; but that has changed now. Bob handling is more sensitive with large radii but bobsleds are faster if the trajectory is right. Pressure and speed cause the ice under the runners to melt, and the bobsled travels on a film of water. The smaller the radius, the greater the depth of penetration into the track and the associated navigation precision. Larger radii work differently. At ETH Zurich’s Department of Materials (D‐MATL) the Surface Science and Technology Group has been conducting intensive work for more than a year regarding ice friction and bobsledding. They have gained knowledge which would generate even more speed if implemented, but which was quite difficult to achieve in practice. Researchers in ETH’s Department of Mechanical and Process Engineering (D‐MAVT) have also explored the engineering aspects of different types of runner forms, especially the longitudinal radius. Interestingly, it seems that runner forms that in theory should lead to faster speed, in practice slow the speed by several seconds. For this reason, researchers have stuck to the classical runner form and have concentrated on optimising it according to the track profile.
In the parc fermé the runners were wiped with a cloth permeated with orange acid. After a certain exposure time they were wiped with a cloth permeated in acetone. Both cloths were preserved in bag, sealed, and labelled with the start number. Then they were collected and stored by the jury. After this process came a second round with the X-ray apparatus to check whether any coatings were present.
Finally, a particular fluid was applied to check the surface tension and ascertain whether there were any forbidden material on the runner not recognised by the X-ray apparatus. Surface tension is the property of a fluid that appears at or near the surface via balanced molecular forces. If the associated energy is higher than the surface energy of a material, the fluid tends to form droplets instead of spreading out. After the whole procedure, the fluid was wiped off again.
Before the bobsleds were put into the starting lane, the runner temperature was measured. The temperature had to be within a range specified by the regulations. If the temperature was too high, the jury specified a certain time during which the bobsleds were placed on an offside bed of ice to cool down.
Following all of this technical activity the race began – and we finally allowed ourselves a well-earned cup of tea. Between the heats, only material issued by the IBSF may be used. Sandpaper in an envelope and cleaning materials were given out and handed back after use. This work may only be carried out by the team members competing in the race. Repairs were permitted by others, if necessary, but only under the supervision of the jury.
As soon as all envelopes were collected, we returned to the control container to prepare the bobsleds controls after the race. Under the supervision of a jury member, selected teams were required to bring their sleds to us for a post-race check. The inspection included checking the frame construction, material alloys and the dimension of the hull. The details of what happens in the container were confidential, and photography was forbidden.
Our long workday came to an end at about 00:15 in the morning. Before turning in for the night, we convened for a celebratory nightcap in the hotel lobby to relax and discuss the day. It was interesting to see how much time and money the teams invested in bobsled construction and material, just to ensure a decisive fraction of a second. With all of our knowledge about materials, what really makes a sled fast remains a mystery. There were bobsleds built according to the same plan and that used exactly the same materials, but one was fast and the other was not. The future may bring us research, calculations and, of course, “stabs in the dark,” but no one really knows what the outcome will be.
Not every day during our Olympic adventure was as full as this one. We also had time to visit the Olympic Park and to watch various events. The Games were fantastically organised and there were always volunteers around. What also impressed me was the relaxed atmosphere among the athletes, despite the great display of emotion when they reached – or when they missed – their intended goal. We found the Korean people open and friendly even though we sometimes had to communicate non-verbally. Overall, it was an unforgettable experience.
By Martin Elsener
After working at Oerlikon-Bührle AG, Altorfer Maschinen AG and ETH Zurich at the institutes for Metal Physics and Technology as well as Surface Science and Technology, Martin Elsener is today head of the workshop at D-MATL. He leads a team of seven, organises internships and works in several initial intervention groups. His function as a material inspector at the IBSF began in 2010. Here he attends to the racing series Europe Cup, World Cup and Youth Series.
