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mshorten69
02-18-2002, 12:33 PM
Steve:

I had the pleasure of working with the team that developed the "Swift" speed
suits, including two aerodynamicists (Chet Kyle and Len Brownlie) and two
NIKE apparel wizards (Rick MacDonald & Eddie Harber) and

The goal of the program was to make use of the properties of some new
synthetic materials to reduce the drag on fast moving athletes. We began
with kinematic analyses of sprint runners using video of World Championship
100 m races from Athens. Using simple geometric forms to represent segments,
we estimated air flow and drag during the running step and calculated the
orientation of segments at which drag would be greatest. Materials with
different surface properties were selected for different regions of the suit
based on the estimated velocity and direction of air flow over different
parts of the body. In general, each material was selected, based on wind
tunnel testing, to encourage microturbulence in the boundary layer, thus
delaying wake separation and reducing drag. The different patches you see on
the suits are these different materials. Seam placements, hood profiles,
etc., were also designed with drag reduction in mind. Also, patches of
low-friction materials were used in areas where limbs rub against one
another.

The first suits were used in Sydney and a new design, based on more
kinematics and wind tunnel data and tuned to the higher velocities and more
stable body configuration of speed skaters is currently being used in Salt
Lake City by the American, Dutch and Australian teams.

"Effectiveness" is tough to measure since the projected benefits are small
compared with many other factors, including the psychological effect of
being given a suit that is intended to enhance performance. Wind tunnel
testing shows a significant reduction in drag compared with conventional
suits, and models can be used to estimate how much that drag reduction will
affect performance. The calculated performance differences for sprinters are
small, but greater than the margin by which Marion Jones lost the World
Championship 100 m last year. The speed skaters are more likely to benefit
because of their higher average velocities. It is doubtful if we will ever
know the real effect with any precision, however. The manikins used in the
wind tunnel are static and the athletes, obviously, are not; so there are
dynamic effects that we cannot account for. Also, while times in Salt Lake
can be compared with "expectations", there are no direct experimental
controls to compare with Olympic performances. I hope to compare individual
performances in Salt Lake with each athlete's previous personal record, to
see if those wearing the new suits did better, relative to their previous
best, than those in conventional suits. This comparison will provide an
interesting anecdote but, since the distribution of suits among athletes is
not random, it will not be a definitive test of "effectiveness".


Cheers,

Martyn Shorten
BioMechanica, LLC.
Portland, Oregon, USA





-----Original Message-----
From: Steve LeBlanc [mailto:zeppo@IS2.DAL.CA]
Sent: Friday, February 15, 2002 11:17 AM
Subject: speed skating suits


In watching the Olympic speed skating competitions, I notice that many of
the body suits the athletes are wearing seem to have special patches of
textured material or other irregularities. Are these used to try to reduce
drag from wind resistance somehow? I am assuming this would be similar to
some of the textured swim suits seen in Sydney.

Perhaps someone with insight into the body suit and/or bathing suit
designs could enlighten us on the effectiveness of these "sartorial
innovations".

Steve LeBlanc MSc
Instructor, School of Health and Human Performance, Dalhousie University
Email: Steve.LeBlanc@dal.ca Webpage: http://is2.dal.ca/~zeppo/
================================================== ======================
"I've done...questionable things. Nothing the god of biomechanics
wouldn't let you into heaven for."

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