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Aerodynamics, ergonomics, structural analysis and materials
technology: Technology partner BMW optimises the sporting
equipment for the German Bobsleigh and Sled Sports Federation (BSD). -
Intensive development in the aerodynamic test centre and
energy test centre of the BMW Group. -
Chasing the crucial hundredth of a second in the ice
channel, the BMW technology transfer from car manufacturing made a
valuable contribution.
Munich. The German Bobsleigh and Sled Sports Federation (BSD)
athletes have a score to settle at the Olympic Games in Pyeongchang
(KOR) in February 2018. Four years ago, the successful bob athletes
came away without a medal. At the three world championships that
followed, Germany returned to winning ways and appears to be ready
for the Olympics. BSD technology partner BMW was also involved in
the development of the sporting equipment. A whole host of BMW
engineering expertise is incorporated into the sleds: aerodynamics,
ergonomics and structural analysis.
As the long-standing premium and technology partner of the BSD, BMW
supports the association with the development and optimisation of the
sleds. BMW brings its extensive expertise from car manufacturing, as
well as its unique infrastructure. In the BMW Group’s aerodynamic test
centre and in the wind tunnel, the BSD is able to test and optimise
the sporting equipment, as well as consult with the BMW aerodynamics
experts. BMW also provides important expertise on carbon technology.
In the area of CFRP (carbon-fibre-reinforced plastic) in particular,
BMW has unique knowledge as the first car manufacturer to make use of
the material carbon in mass production.
Ergonomics and materials technology.
Bobs are manufactured from carbon, a material with which BMW is very
familiar; BMW demonstrates its expertise not only in car manufacturing
and motorsport, but also in the America’s Cup, the most challenging
sailing competition in the world. Thomas Hahn, who is head of the BMW
technology transfer, has spent many years working on the construction
of the high-tech racing yachts for two-time America’s Cup winner
ORACLE Team USA. He knows the challenges and the potential of carbon.
The aerospace engineer uses his specialist knowledge to support
bobsleigh builder Johannes Wallner, who manufactures the 2-man and
4-man bobs for the reigning world champion bob teams Lochner and Friedrich.
“First, we measured and digitalised the bob, and optimised it using
computer simulation,” explained Hahn. “To produce the prototypes, we
used a precision mill to manufacture a negative mould that will then
be used to bring the carbon fibres to the exact desired positions.
This precision form guarantees that the test, measurement and race
results are transparent and comparable. Which means the sleds produced
can be reproduced identically.”
The positions of the three pushers require different qualities. For
example, two requires more power, four requires more speed and a
higher step frequency. In the 4-man sled of Francesco Friedrich, this
position is held by former decathlete Thorsten Margis, who is an
imposing 1.92 metres tall. He needs more space to position himself as
flat as possible in the bob to reduce air resistance. The position of
his seat needed to be adjusted for this.
Head coach René Spies said: “Over the summer we optimised the Wallner
bobs for the teams Friedrich and Lochner. Many ideas for improving the
aerodynamics of the sleds and for the seat positions were developed
and implemented. The valuable tests in the BMW wind tunnel enabled us
to confirm the positive results and get that last hundredth of a
second for our Mission Gold. A big thank you goes to BMW for this.”
Hahn said: “Changing the seating positions is nowhere near as trivial
as one might think. Such optimisations change the centre of gravity
and the handling, among other things. But we are very pleased with the
result. Identifying and implementing the optimum compromise is a
challenge that has to be mastered every day in car manufacturing.”
Aerodynamics.
The seating positions of the athletes have a huge influence on the
aerodynamics. The strict regulations allow only very restricted
options for optimising the sleds. “The aerodynamic losses related to
the crew and shape of the sled need to be minimised,” said Lochner.
“The wind tunnel of the BMW Group is invaluable for getting the last
modicum here. We need to scrape together every hundredth of a second
that we can find so that we can celebrate a gold, silver or bronze
medal again at the Olympic Games.”
Friedrich confirmed this: “The aerodynamics are crucial in the 4-man
sled in particular. The BMW wind tunnel is extremely high-tech. We
were able to take a lot of measurements and try out various options
within a very short time, which we probably couldn’t have done
anywhere else. It is fantastic.”
The sophisticated infrastructure of the BMW Group’s Research and
Innovation Centre (FIZ) in Munich, which the BSD has access to,
contains one of the largest and most innovative wind tunnels in the
world. It facilitates wind speeds of up to 300 km/h. And, thanks to
enormous computing capacity, various aerodynamic models can be
calculated within a very short time. “We can optimise the bobs here in
exactly the same way as we optimise our cars,” said Holger Gau, BMW
expert for 3D simulation methods. “We look at turbulence, analyse
pooling regions and use appropriate shape changes – or changed seating
positions – to try to minimise resistance.” A final test before the
Olympic Games showed that the aerodynamic measures achieved a
reduction in air resistance of up to six percent. In theory, this
should make the sleds a tenth of a second faster per run. However,
compared with the test laboratory, factors such as weather and track
conditions, as well as the sliding line, are significant in the ice channel.
Like in the car development process, the majority of the work is
first done on the computer. And the BMW Group has first-rate equipment
for the virtual tasks as well. “We use high-performance software tools
to evaluate the aerodynamics of the combination of the bob and the
team, and to optimise this virtually. Then the verification and
fine-tuning take place in the wind tunnel,” explained Gau. “It’s all
about finding the optimum way to interlink the advantages of both
worlds – digital and real-time in the wind tunnel.”
And the potential is by no means exhausted. In the BMW Group’s energy
test centre (EVZ), three thermal wind tunnels and two air-conditioned
chamber test beds can simulate snow, rain, cold, heat and even
altitude. The same facilities that make the BMW vehicles more
efficient in a variety of climatic conditions provide the winter
sports athletes and their sporting equipment with controlled test
conditions, which are like those they will really experience in the
ice channel. BMW hereby makes another contribution to BSD continuing
their success at the 2018 Olympic Games.