Shaun White & Engineering the Half Pipe
Shaun White is known for his spectacular tricks in the Olympic snowboard half pipe event. More than just his incredible athletic skill and years of training, it's also the engineering and design of the half pipe that allows White to gain enough speed to generate big air. "Science and Engineering of the 2014 Olympic Winter Games” is produced in partnership with the National Science Foundation.
LIAM McHUGH, reporting: Whether or not you're a fan of the Winter Olympics, it is likely you know his name.
Announcer: Shaun White, incredible execution!
McHUGH: Claiming his first gold medal in 2006, a feat he repeated in 2010, Shaun White has long been the biggest name in the snowboard half pipe event.
Announcer: It's athletes like Shaun White that make you think the impossible is possible.
SHAUN WHITE (Snowboarding Gold Medalist): The only trick you really remember is the last one because it’s the do or die trick, you better make that one to get that score.
McHUGH: With tricks that dazzle fans and fellow snowboarders alike, at times Shaun White seems to defy the laws of nature.
Announcer: All eyes to this hit. Oh!
WHITE: I had worked so hard at that point to learn this trick, the Double-McTwist 1260, I had crashed time and time again.
Announcer: There it is, right there. Oh my gosh! That is a move that encompasses three and a half rotations, two flips, the Double McTwist!
McHUGH: What allows Shaun White to do these tricks is more than just his incredible athletic skill and years of hard training. It's also the engineering and design of the half pipe that allows him to gain enough speed to generate big air.
BRIANNO COLLER (Northern Illinois University): Height is all speed. If you can get that speed, you can get the height.
McHUGH: Brianno Coller is an engineering professor at Northern Illinois University and funded by the National Science Foundation. He says an important factor in the design of the half pipe is the height of the walls and the radius, or curvature.
COLLER: The reason why you make your wall higher is so you can fit a bigger radius inside that curve.
McHUGH: At the 2014 games in Sochi, engineers have built a half pipe that is 22 feet high, 65 feet wide, and 557 feet long. The radius is crucial because it allows the snowboarder to change direction at high speeds, from barreling down the hill, to soaring into the air.
COLLER: While he's going around this turn, he's experiencing some rather dramatic forces. You have to take this momentum that's going this way, convert it to momentum going that way.
McHUGH: As Shaun White rides the curve of the half pipe, he has a velocity, a speed with a direction. As he begins to change direction, he experiences what scientists call centripetal acceleration.
COLLER: You might be headed this way, and then be headed this way, and because you're changing direction, you actually get an acceleration that way.
McHUGH: Acceleration is defined as the rate of change in velocity. Acceleration that changes direction is called centripetal acceleration. As Shaun White changes direction by riding up the curvature, he is experiencing centripetal acceleration. For snowboarders like White, the force from centripetal acceleration can be over two G's.
COLLER: The extra force that Shaun White feels just by going around that curve is about two and a half, 2.7 times his own weight. Shaun White has to carry his own weight plus the two and a half times his own weight just to pull himself through that turn.
McHUGH: If Shaun White wanted to get twice as much air, he would have to increase his speed by almost half. Entering the curve at this higher speed would require an increased acceleration to change his direction, placing a much greater force on his body.
COLLER: So instead of carrying 2.5, 2.7 times his weight through that turn, he'd be carrying about five times his weight through the turn. It's like putting five of his buddies on his back and trying to maneuver through that transition.
McHUGH: To lessen the force of centripetal acceleration, engineers are continually optimizing the dimensions of the half pipe, allowing for a larger radius. And a larger radius also means higher walls. When the snowboard half pipe made its Olympic debut in 1998, the walls were much lower than they are today. But with each Winter Olympics, advances in engineering and design have led to larger and larger half pipes.
COLLER: They went from twelve feet to fifteen feet to eighteen feet to twenty-two feet. So over the past two decades they've essentially doubled in size.
McHUGH: Allowing snowboarders to go faster, get more air time, but not increase the forces on their body.
COLLER: The more gentle this turn is, the lower those forces are. So if you make that radius twice as big, you make the wall twice as big, that force gets cut in half.
WHITE: Whether you win or lose, you're an Olympian so it doesn't matter. You're there for the thrill of the fight.
McHUGH: This close relationship of half pipe design to maximize speed and air time allows snowboarders like Shaun White to push the limits of their skill, bringing the sport to new heights.