Skates used by Olympic speed skaters, figure skaters and hockey players are custom-engineered by materials scientists so that the boots and blades meet the demands for each sport. NSF-funded scientists Melissa Hines, Director of the Cornell University Center for Materials Research, and Sam Colbeck, formerly of the U.S. Army Cold Regions Lab, explain, along with U.S. Olympic hockey player Julie Chu, short track speed skater J.R. Celski, and figure-skater Rachael Flatt.
The Science of Skates
LESTER HOLT, anchor:
The ice skates worn by this year’s hockey players, figure skaters and speed skaters are greatly different from those once used. Learn from this year’s winter Olympians and materials-scientists and researchers funded by the National Science Foundation how innovations in boot and blade design help skaters perform better than ever before.
HOLT: Speed skaters need them, to race around tight corners at break-neck speeds. Figure skaters need them, to glide, spin and spiral during their routines. Hockey players need them, to chase down pucks, and turn on a dime. Olympic Ice Skates – at first glance, they look like skates have looked for decades. But in fact – with innovations in materials science – skates are now specifically engineered to give the best competitive edge to the individual athletes who lace them up.
The engineering starts with the boot. Two-time U.S. Women’s Hockey player Julie Chu needs skate boots that are comfortable -- yet can support her feet for up to 20 straight minutes of high-velocity, high-intensity play.
HOLT: So she wears boots made from synthetic materials that form-fit to her feet when heated.
JULIE CHU (U.S. Hockey Team): You're really just warming them up so that the inside molding or the inside material is a little bit softer, and then you put your foot in it and it just molds to your foot as it cools down.
HOLT: Form-fitted boots also help the player apply more energy and force -- more directly -- to push off the ice and skate.
Dr. MELISSA HINES (Cornell University): And that's really important because any time your uh, foot is moving around in a boot, it's squishing back and forth that’s energy that's not going towards hockey, and you don't want to have that happen.
HOLT: Speed skaters like J.R. Celski have to make tight, high-speed turns, which means their ankles – and their skate boots -- have to flex.
J.R CELSKI (U.S. Speed Skating Team - Short Track): These skates are built from the base up, starting with the boot. They're custom made so they're carbon fiber mostly and they're very hard, but there’s a lot of flexibility in the ankle so when we are skating we can push out knees forward and get a lot of movement wherever we want to go on the track.
HOLT: Figure-skating boots are just the opposite: they have to be stiff -- support the ankle through all those axels, lutzes, and salchows. What space-age material are they made of? Layers of old-fashioned leather.
Dr. HINES: It turns out that nature is really good at making uh, materials. Things like leather have great attributes that are used still today in things like figure skates, where you want to have the right blend of stiffness and also movability, also suppleness.
HOLT: As for the skate blades – in one way, they’re all alike: made of high-quality steel. But blades, too, are engineered and designed for specific kinds of movement. Figure-skate blades, for example, have “toe-picks” – pointed teeth at the front of the blades – that skaters like Rachael Flatt can use to dig into the ice, to stop or launch a jump. And to help her maneuver gracefully on turns, the bottom of each blade has a center groove separating two thin separate edges.
RACHAEL FLATT (U.S. Figure Skating Team): It’s tilted a little bit to the inside or to the outside. When you're tilting to your right, you're going to be on the inside of this blade, but when on your right skate, it will be outside of your blade.
Dr. HINES: So the little sharp edges help you steer, the sharp parts of the skate can actually dig into the ice and give you a little bit of extra impact, a little bit of extra oomph.
HOLT: Blades on hockey skates are built for speed. They’re shorter, lighter, to help hockey players skate fast, stop fast, and turn fast.
CHU: We have to always be going forward and backwards as well as transition. So I think the shorter blades allow us to be a little bit more agile on the ice.
HOLT: Speed skaters, who don’t have to make quick pivots, have longer and wider skate blades, to help them glide. It’s surface physics: The movement of the blade over the ice creates friction, which generates heat – which creates a thin layer of melt-water for the skate to glide on. A wider, longer blade generates more heat, more melt water, more glide, it’s an advantage to keep the blade on the ice as long as possible – whenever contact is broken, heat is lost.
Dr. SAM COLBECK (U.S. Army Cold Regions Lab): I see that in my temperature measurements with skates, because when you glide, the skate is heated up. When you pick it up, it's cooled. So there'd be an advantage to keeping the skate on the ice, and continuously keeping the skate bottom warm.
HOLT: That's the advantage of the clap-skate, used in long track speed skating: A hinge connects the skate to the boot – allows skaters to pick up their heels – yet leave their skate blades in contact with the ice just a bit longer, to glide farther, faster on the long straightaway’s. Short track speed skaters who don’t have long straightaway’s -- wear skates with blades fixed in a carefully calculated position.
CELSKI: Our blades are actually set up in our boots, so that when we are angled, our boots don’t rub on the ice -- we are able to lean as much as we can without, you know what’s called “booting out” on short track.
HOLT: The science and engineering of boots and blades - for Olympic contenders, what they'll wear around their necks can depend on what they wear on their feet.
Science Activity (Grades 6-9) from Lessonopoly
THE SCIENCE OF SKATES
Objective: Understand the important differences between skates used in different sports through a classroom experiment.
This activity is intended as a supplement to the NBC Learn Video THE SCIENCE OF SKATES.
The video deals with how skates, both the blade and the shoe, are differently designed for the three main skating sports: figure skating, hockey, and speed skating.
One of the least known aspects of skate blade design depends on the fact that pressure increases temperature. (e.g. Why did the center of the earth and sun initially get hot? Why do heat pumps work?) When a skater’s blade comes in contact with the ice, there is a great amount of pressure involved, especially when turning a corner. This pressure causes a very thin layer of the ice to turn into water which essentially “oils” the surface for a low friction glide. The designers of Olympic skates make use of this effect and the activity below demonstrates it.
Activity Procedure: These steps below will set up demonstrations of the pressure heating effect and also allow an observation of some variables that affect the amount of heating.
(1) A few days before the activity is to be done, make at least three small bricks of ice. Quart size, cardboard milk cartons would be about right.
(2) Obtain three lengths of steel wire. Each length should be about two feet long. Two of the lengths should be thin (like a string), while the other should be somewhat thicker. A hardware store can show you what “gauge” of wire would be used to measure these thicknesses.
(3) The blocks of ice need to be raised up so that the wires can loop over the block and hang down on two opposite sides of the block. The ends of the wire need to be adapted so that weights can be attached so that the wires are able to pull down through the ice.
(4) The demonstration works best for maximum pressure (maximum weights), but you must set an appropriate limit for safety.
(5) Hang the same (maximum) amount of weight on the thick wire and on one of the thin wires.
(6) The other thin wire should have a smaller (half?) weight.
(7) Be sure to have a good supply of old towels around to soak up the melting water.
(8) Start all three ice block “slicers” at the same time, and keep track of the amount time it takes for the various blades to cut down to deeper and deeper levels. You will probably find it best to measure the progress in millimeters and minutes.
Questions to think about:
(1) Which of the wires “cut” faster?
(2) Why do skaters want a thin layer of water between their blade and the ice?
(3) Why aren’t ice skate blades thin like the wires?
(4) What happened to the “water” above the cuts?
Question about Olympic skating:
(1) Why do speed skaters have long blades while figure and hockey skaters have shorter blades?
There was an important sports birthday this week. The National Hockey League (NHL) played its first games 100 years ago, on December 19, 1917. The Montreal Canadiens beat the Ottawa Senators, 7-4, while the Montreal Wanderers (a weird name for a hockey team) edged the Toronto Arenas, 10-9.
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