On February 11, mainland athlete Yan Wengang won the bronze medal in the men's steel frame snowmobile event of the Beijing Winter Olympics, which was the first time that a Chinese athlete had reached the podium in the event.
His companion Yin Zhengze set a track start record, both of which made history.
Steel frame snowmobiles, snowmobiles, sleds, are all racing projects on a track, I believe that many people not only can not distinguish their differences, but also can not see the doorway inside, this article to briefly introduce these "sled" projects and the science behind them.
Written by | snow
As the 2022 Beijing Winter Olympics draw to a close, as an ordinary Chinese audience, we must pay the most attention to our gold-winning projects, such as short track speed skating, freestyle skiing, etc., while other sports always have the mentality of watching the hilarity. And of all the Winter Olympics, perhaps the most "unconscious" event is the three racing events of snowmobiles, steel frame snowmobiles and sleds - lying or lying down or sitting, turning a few laps to end the race, the difference between victory and defeat is only a millimeter, which is really confusing.
However, this is also the biggest feature of these sports. Snowmobiles, known as ice F1; steel frame snowmobiles, known as ice divers; fast as the wind, as lightning, in fact, they are really hardcore competitive sports, everywhere reflects the charm of sports and technology.
Yan Wengang in the game 丨 Image source: IC photo
The difference between a bobsleigh, a snowmobile and a steel frame snowmobile is the same as the venue
Sleds, bobsleighs and steel frame snowmobiles, although the shape is different, but from the equipment point of view, they are actually sled (sled, sleigh). As a general spectator, it is not difficult to distinguish between these three sports, and the easiest way is to look at the body shape of the athlete.
Luge, also known as luge, is a way in which athletes race with their feet in front of them and lying flat on the sled. At the start of the race, the athlete sits on the sled and pushes his arms back against the ice to get the first speed. Sledding is an ancient way of transport and travel for humans, and it is recorded that there were bobsleigh races in the 15th century. Luge originally means small and medium-sized sledding in French. Modern luges became an official sport at the 1964 Winter Olympics in Innsbruck.
2022 Beijing Winter Olympics Bobsleigh Men's Double Free Sex Competition 丨Pic Credit: Daniel Mihailescu/AFP
Bobsleigh, as the name suggests, athletes sit in the car and "drive" the race. Snowmobiling is the oldest Winter Olympics, existing since the first Chamonix Winter Olympics in 1924 (only the 1960 Winter Olympics in Valley were absent). In 1877, the Swiss invented the bob steering sled, which gradually developed into a race, so it was also known as a bobsleigh. The project is usually a team competition – two- or four-person, with the first helmsman pulling the steering to control the direction; the last person in the back seat is the brakeman, who controls the in-car pusher brakes (almost no use during the race). For the first time, this year's Beijing Winter Olympics joined the women's singles snowmobile event (Monobob). At the beginning of the race, the athlete needs to run to push the retractable pushrod on the snowmobile (the armrest of the brake trolley) to accelerate the cart, run in a straight line for about 50 meters, and then quickly burrow into the car and start sliding.
Four-person snowmobile project, after starting the race, from the frontmost helmsman to the last brakeman jumped into the car in turn 丨 Image source: IBSF
Snowmobile components 丨 Image source: adventure.howstuffworks.com
The Skeleton is a one-man sport in which athletes start with a sleigh and then race head-forward on the sled, which is equipped with bumpers. The sport of steel frame bobsleighs also originated in the 19th century, and in 1892, sleds made of pure steel, that is, steel frame bobsleighs, were born. As for why it is called "Skeleton", some people speculate that it is because the most primitive "wooden sled" is more like a bone, and some people think that the Norwegian sled "Kjaelke" is mistranslated as "Skele". Whatever its origins, the steel-framed snowmobile has always been a popular winter sport – it was removed from the Olympics for being too dangerous and returned in 2002.
Steel frame snowmobile project丨 Image source: Insider
One of the biggest reasons for the three races of bobsleigh, bobsleigh and steel frame bobsleigh (hereinafter referred to as bobsleigh sports) is that they share a track, and the bobsleigh and the steel frame bobsleigh have the same starting point, and the bobsleigh has another starting point.
The Beijing Winter Olympic Bobsleigh Race was held at the National Bobsleigh Center in Yanqing, Beijing, with a total length of 1975 meters (race length of 1615 meters), 16 curves with different angles and slopes (maximum slope 18%, average gradient of 6%, and the world's first 360 degree curve), vertical drop of 121 meters. To meet the requirements of high-speed taxiing, the bobsleigh track is designed as a complex spatial three-dimensional curved surface. The National Bobsleigh Center is the first track in China and the seventeenth in the world to be certified by the International Snowmobile Federation (IBSF); it is shaped like a dragon hovering between the mountains, hence the name "Snow Dragon".
National Bobsleigh Center and its Track Map 丨Pic credit: IBSF
fast! Depends on physics
Bobsleigh is one of the fastest events in the Winter Olympics (alpine downhill skiing is also fast), with a maximum speed of 150Km/h for four-person bobsleigh races and 140km/h for bobsleighs. The source of such a high speed is actually very easy to understand - gravity, the athlete only relies on the gravity of the man and the sleigh to move from high to low. In this process, gravitational potential energy is converted into kinetic energy, both of which are proportional to mass, so the greater the mass, the same as all other conditions, and the four-person snowmobile will be the fastest.
The IBSF's rules for snowmobile programs strictly limit vehicle weight, and inadequate weight may require counterweights to be added to the car – how weight is distributed within the snowmobile will play a key role in speed. Before and after the race, the race team members and the snowmobile are weighed.
Weight limits for bobshoes and steel frame bobscars
Behind the winding, snow-covered track, there is a stage where various physical laws reflect each other - a perfect track environment, ice friction, air resistance is the key factor affecting speed; at the same time, the bobsleigh itself needs to have excellent performance and athletes are properly equipped. The athlete's performance on stage is the decisive factor in becoming a champion, and he will be the first person to deal perfectly with all the subtle physics phenomena.
It must be noted that bobsleighing is a dangerous sport. When cornering sharply, athletes will be subjected to accelerations of up to 5 to 6 g for several seconds. The same acceleration we can experience in roller coasters (see Adventurer's Game: History, Physics, and Psychology of roller coasters), but we are safely fixed to the saddle the whole time, and the racers can only rely on their own muscle control. At the 2010 Winter Olympics in Vancouver, a Georgian athlete died while sliding off the track while training. On the other hand, the consequences of head impact are also unpredictable, and athletes also have to endure the huge noise generated by the sled during the competition, and some studies believe that such a state may cause mental illness for a long time. (For a concussion caused by exercise, see Women's Soccer Wins!) The role of the header is crucial, but at most there will be "occupational diseases", and severe cases will suffer from Alzheimer's disease")
Make good use of aerodynamics
Most of the bobsleigh events at the Winter Olympics are about 1.6 kilometers long, and runners can complete the course in 1 minute. The competition is played in four rounds, and the final result is the sum of the four rounds. Even so, the gap between the champions and runners-up is only a few hundredths of a second, or even a few thousandths of a second. Aerodynamics plays an important role here. Early wind tunnel experiments and computational fluid dynamics (CFD) studies showed that air resistance accounted for 20 to 26 percent of total resistance; reducing resistance by 3 percent would increase the final score by a tenth of a second.
As far as snowmobiling is concerned, its main resistance comes from the pressure difference resistance. In terms of the size of the car body, general information may give approximate restrictions, such as a four-person snowmobile not exceeding 3.8 meters. (In luge and steel-frame bobsleigh races, "bobsleighs" are also severely restricted.) In fact, the International Snowmobile Federation has very strict rules on the design of modern snowmobiles, and the design drawings are directly given in the rules introduced. The reason for this is to ensure the safety of athletes while playing a level playing field. Of course, there is also some flexibility here, so the technical content of the snowmobile design is highlighted - modern snowmobiles are designed to be more aerodynamically streamlined. The overall body shell (fairing) and the geometry of the turf (especially the front and rear wings), as well as the front and rear splices, the position of the brakes, etc. will all have an impact on speed.
The manufacture of snowmobiles also needs to consider their materials. Although the overall weight of the snowmobile is large, the sports steering needs to be very easy to maneuver while ensuring the safety of the athletes, the body needs to be very light and impact-resistant, and the chassis needs to be extremely strong. Manufacturers will opt for carbon fibre composites – a world-class bobsleigh will cost £25,000-70,000, while the glide mechanism (skid edge) below will also cost £4,000-10,000. Athletes wear mask-style helmets, rather than a combination of helmets and goggles, also to reduce air resistance.
The leading designers of snowmobiles belong to only a few producers. The first domestic snowmobile was made by China Aerospace Science and Technology Group and China FAW丨Pic credit: CGTN
In fact, in addition to winter sports such as figure skating and curling, air resistance has a great impact on most winter sports. In some sports, such as ski jumping competitions, official organizations will even restrict the use of innovative technologies that reduce air resistance, just as sharkskin swimsuits have been banned in swimming competitions. From fabrics to prints, breathability and elasticity, scientists have explored all aspects of winter sportswear. However, the bobsleigh project does not have strict requirements for installation – after all, the body control is slightly worse, and the impact is much greater than the aerodynamic effect. They generally wear tight sportswear and gloves, with nails on the bobsleigh sports to help them start, and snowmobilers wearing spikes.
Gloves of bobsleigh racers 丨 Image source: Sportsmatik
Overcome friction and adjust the optimal route
If you want to ask, why is ice slippery? It's a question that physicists have spent hundreds of years still haven't found a definitive answer to. Early research suggested that a film of water formed on the surface of the ice to lubricate, a phenomenon originally discovered by Faraday. In 1987, scientists confirmed through X-ray diffraction that there is indeed a quasi-liquid layers (QLL) on the surface of the ice, with a thickness of only a few tens of nanometers, and later found that this is a metastable transient that exists when ice sublimates and water vapor grows. However, in theory, it has not been possible to find out why the experiment observed that the friction will be greater when the temperature is near the melting point of the ice than at low temperatures. The above text is just to illustrate that there is too much knowledge about water (ice, snow); just mention winter sports, the sliding friction coefficient at different relative speeds is difficult to determine; air humidity also has a great impact on the friction coefficient of the ice surface. This is also the biggest source of resistance for bobsleigh sports - the friction between the blade and the ice surface; but after all, the environment of the competition venue is not determined by the players, and to overcome the friction, they also need their own level.
Theoretically, the researchers modeled bobsleigh motion, from the simplest model of a one-dimensional particle of a prescript track to a complex model that treats athletes and sleds as rigid bodies, and both theoretical results and actual races tell us that the glide trajectory will be a key factor in the victory. Simply put, athletes should be good at planning routes and shortening the total distance. Watching the race is easy to see that if an athlete stumbles on the edge of the track after turning, or if the route is not so perfect, the final result will be greatly reduced.
Luge races require complete "lying flat" and steel-framed snowmobiles "lying flat", with subtleties such as their bodies, leg positions and head pitch angles. In steel-frame bobsleigh races, if a runner looks up at the track and the center of gravity of the body may change, it may lead to off-track. In the snowmobile event, the athlete's sitting position in the car has a greater impact on the trajectory of the movement (and also affects the aerodynamics).
Ideally, the basic force analysis of the bending straight and the curve is very complicated, but the current turning simulation and experimental coincidence are very high
Because the bobsleigh and steel frame bobsleigh have a section in front of them, and this part has an impact on the overall performance, many athletes in this event have transitioned from track and field. In such a tense and exciting race, the most joyful moment for the melon eating crowd may be that the car is out and the person does not go up (if it is a multi-person game, the teammate may be able to drag him in).
Influencing factors of the start-up stage of the steel frame snowmobile cart
Therefore, the athlete's physical sensation and control are the factors that really determine victory or defeat. The game is changing rapidly, and it is difficult for the audience to see how those thrilling links are skillfully handled by excellent athletes - dozens of cameras are set up throughout the process, and we can only look at a rough idea. That's why when you watch a game, you feel like they're all in the same position, but some athletes are just fast.
Snowmobile sledding is difficult, so let's play climbing the plow.