Go for Gold: Olympic Aerodynamics

Posted on Fri, February 23, 2018

How do ski jumpers go for the gold? Aerodynamics!

As you’ve watched the ski jumpers competing in the Winter Olympics, have you ever wondered why they assume the positions they do during the inrun and jump? It’s not just a silly skiing style, it’s aerodynamics in action—and it’s the same rules that impact airplanes in flight.

A ski jumper competing in the FIS Nordic Combined World Cup on February 4, 2017. Credit: Republic of Korea Ministry of Culture, Sports and Tourism via Flickr.

Generating Lift, Reducing Drag

Aerodynamics is the way that an object moves through the air, be it a skier or a 737. Forces (lift, weight, thrust, and drag) make that object move through the air, faster or slower, and up and down. That means balancing weight with its opposite force, lift. While weight comes from gravity pulling an object back down to Earth, lift is the force that moves the object up.

For a ski jumper, that means he or she has to reduce drag and generate lift, in order to go faster and farther. Just like how an airplane’s wing generates lift, a skier’s body assumes a shape designed to help provide lift: During the inrun before the jump, skiers keep their chests parallel to their skis, with their heads down and arms back, to decrease drag and increase speed. Once skiers leave the ramp, they adjust their bodies to maximize lift. When a ski jumper leans forward into the wind, he or she is forming a streamlined shape, providing lift and reducing pressure drag, making it easier for the skier to move through the air. In recent years, skiers have also begun positioning their skis in a “V” shape during flight—this increases the surface area exposed to the oncoming air, generating more lift.

Team USA ski jumper Sarah Hendrickson training in a wind tunnel, 2014. Credit: Sarah Hendrickson via Facebook.

Measuring the Forces

How do we understand an airplane’s aerodynamics? Engineers use wind tunnels to test their designs. Wind tunnels are tubes that move air around an object—sometimes a scale model of an aircraft, sometimes an actual one—so engineers can measure those forces. Wind tunnels help engineers make sure that an aircraft will fly the way it’s designed to.

It turns out some ski jumpers use wind tunnels to see how they’ll move in the air, too. Team USA ski jumper Sarah Hendrickson prepared for the 2018 Winter Olympics by training in a wind tunnel. Working in a wind tunnel helped Hendrickson figure out the best possible angle to lean into the jump, called an angle of attack, to create as much lift as possible with the least amount of drag. Finding the optimum angle of attack can help a ski jumper go farther—and can mean the difference between a gold and a silver medal!

As she described her wind tunnel training in an interview before the Olympics, Hendrickson said, “Ski jumping is the closest you can get to flying. It’s speed, it’s adrenaline… This is what I do, I fly every day.”

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