Tag: ski jumping

Beijing 2022: Ski Jumping
In ski jumping, aerodynamics are paramount. Each jump consists of four segments: the in-run, take-off, flight, and landing. Of these, aerodynamics dominates in the in-run — where jumpers streamline themselves to minimize drag and maximize their take-off speed — and in flight. During flight, ski jumpers spread their skis in a V-shape and lift their arms to the sides to turn themselves into a glider. Their goal is to maximize their lift-to-drag ratio, so that the air keeps them aloft as long as possible. Because of the short flight time and high risk of taking jump after jump, many elite ski jumpers use wind tunnel time to practice and hone their flight positioning, as seen in the video below.
Weather also plays a significant role in ski jumping; it’s one of the few sports where a headwind is an advantage to athletes. To try to adjust for wind effects, scoring for the sport uses a wind factor. (Image credit: T. Trapani; video credit: NBC News)

February 8, 2022
PyeongChang 2018: Ski Jumping
No winter sport is more aerodynamically demanding than ski jumping. A jump consists of four parts: the in-run, take-off, flight, and landing. The in-run is where an athlete gains her speed, and to keep drag from slowing her down, she descends in a streamlined tuck that minimizes frontal area. The biggest aerodynamic challenge comes during flight, when the jumper wants to maximize lift while minimizing drag. The athlete spreads her skis in a V-shape and flattens her body, using her hands to adjust her flight. Flying the farthest requires careful management of forces while in the air. Wind plays a major role as well, with headwinds helping athletes fly farther. To compensate, scoring includes a wind factor calculated based on conditions for each jump. (Image credit: B. Pieper, Reuters/K. Pfaffenbach, PyeongChang 2018)
February 14, 2018
Sochi 2014: Ski Jump, Part 2
Yesterday we talked about the technique ski jumpers use to fly farther. Generating lift without too much drag is the key to a good jump. But jumpers are subject to ever-changing wind conditions, and those can help or hurt them. Unlike most sports, in ski jumping a headwind is desirable. This is because the added relative air velocity increases the jumper’s lift and helps them fly farther. A tailwind, on the other hand, saps their speed. Since 2009, ski jumping competitions have included a wind compensation factor that tries to account for these effects. Wind velocity is measured at five points along the jumper’s flight path and the tangential (i.e. head- or tailwind) components are weighted and averaged. The weighting factors seem to be individual to each hill – not all hills are built with the same profile. This average tangential wind speed is then a linear variable in an equation for wind factor. The goal of the wind factor is as much to make the competition run smoothly as it is to increase fairness. The trouble is that the wind speed effect is non-linear; in other words, a headwind does not help a jumper as much as a tailwind can hurt them. In one simulation study, researchers found a 3 m/s headwind carried jumpers 17.4 m further while a tailwind of the same magnitude shortened the jump by 29.1 m. The wind differences in competition may not be as drastic, but truly evening the playing field may require a more complicated compensation system. (Photo credit: B. Martin/Sports Illustrated)
FYFD is celebrating the Games with a look at fluid dynamics in the Winter Olympics. Check out our previous posts on the aerodynamics of speed skating, why ice is slippery and how lugers slide so fast.
February 14, 2014
Sochi 2014: Ski Jump
Great ski jumpers are masters of aerodynamics. There are four main parts to a jump: the in-run, take-off, flight, and landing. An athlete’s aerodynamics are most vital in the in-run and, naturally, the flight. During the in-run, the athlete is trying to gain as much speed as possible, so she tucks down and pulls her arms behind her back to streamline her body and keep her frontal area as small as possible. This limits her drag so that she can maximize her speed at take-off. Once in the air, though, the jumpers act like gliders. In flight, there are three forces acting on the the jumper: gravity, lift, and drag. Gravity pulls the jumper down, and drag tends to push her backwards up the hill, but lift, by counteracting gravity, helps keep jumpers aloft for a greater distance. To maximize lift, a jumper angles her skis outward in a V and holds her arms out from her sides. This configuration turns the jumper’s body and skis into a wing. The best jumpers will tweak their positions with training jumps and wind tunnel time to maximize their lift while minimizing their drag in flight and on the in-run. Technique is critical in ski jumping, but conditions play a significant role as well. Tomorrow’s post will discuss why and how judges account for changing conditions. (Photo credits: L. Baron/Bongarts/Getty Images; D. Lovetsky/AP; E. Bolte/USA Today)
FYFD is celebrating the Games with a look at fluid dynamics in the Winter Olympics. Check out our previous posts on the aerodynamics of speed skating, why ice is slippery and how lugers slide so fast.
February 13, 2014
Ski Jumping Aerodynamics
Last summer we featured fluid dynamics in the Summer Olympics and there’s more to come for Sochi. Winter athletes like ski jumper Sarah Hendrickson are hard at work preparing, which can include time in wind tunnels, as shown here. There are two main diagnostics in tests like these: drag measurements and smoke visualization. The board Hendrickson stands on is connected to the tunnel’s force balance, which allows engineers to measure the differences in drag on her as she adjusts equipment and positions. This gives a macroscopic measure of drag reduction, and reduced drag makes the skier faster on the snow and lets her fly longer in the jump. The smoke wand provides a way to visualize local flow conditions to ensure flow remains attached around the athlete, which also reduces drag. (Video credit: Red Bull/Outside Magazine; submitted by @YvesDubief)
August 28, 2013