1. Introduction
On the evening of February 11, Yan Wengang won the bronze medal with a time of 4:1.77, which was the first steel-framed snowmobile winter Olympic medal in mainland China; Yin Zheng ranked 5th with a time of 4:2.13 and set a track departure record with a time of 4.58 seconds. The Chinese steel frame snow team achieved breakthrough results at the Winter Olympics. From the picture, after the steel frame snowmobile starts, the athletes lie flat, completely relying on the gravity of the earth to accelerate, so how can the athletes who lie flat operate to make the speed faster?
Yan Wengang
2, speed is the magic weapon
The steel frame snowmobile should be a relatively unfamiliar project, it needs to accelerate the snowmobile as much as possible within 50m of the starting point, and then the athlete directly lies on it, along the fixed slide, with the help of gravity potential energy to continuously accelerate. The track turns nine and eighteen turns, and if you are not careful, you may rush out of the track.
Departure phase
The steel frame snowmobile is accelerated by gravity, the snow tour dragon height difference of the race venue is 121m, the total length of the race track is 1615m, the dynamic friction coefficient between the snowmobile and the ice surface is about 0.035, and the theoretical natural glide finish speed is 128km/h. By the way, the weight of the athlete's body theoretically does not affect the speed of the finish line. According to reports, the top speed of Yanwengang is close to 130km/h. It can be seen that in the process of the game, he basically did not add additional resistance.
Speed estimation
The steel frame snowmobile pursues the ultimate speed, but the steel frame snowmobile has no power device, except for the 50m acceleration at the beginning, the rest of the possible artificial acceleration. It is not like rowing in the water, which can rely on paddling backwards with your hands and feet to provide power. On a steel-framed snowmobile, the "rowing" action speed of the hands and feet cannot keep up with the speed of the snowmobile, which only increases the extra resistance. Therefore, the steel frame snowmobile movement is a sport that determines the result at the beginning, and the first 50m is crucial. The greater the initial speed, the more chances you have to win medals.
Steel frame snowmobile
3. Athletes lying flat are also tired
Since the departure determines the result, can the athlete ignore the process and just lie on it and rest? Obviously impossible. Mechanically there is a fastest descent line, although the distance is longer than the straight line distance, but the time taken is the shortest. The descent of the Snow Dragon is not the fastest descent line, everyone's track is the same, athletes want faster speed, should try to minimize the human intervention of the steel frame snowmobile. In theory, a natural trajectory without intervention is the best path. However, since the track is not completely closed, if you do not intervene, you may rush out of the track when you turn, and the role of the athlete is reflected here.
The steepest descent line
So how do athletes manipulate them? The posture control of the feet, body, and head is crucial to the impact of the snowmobile's forward trajectory. The athlete's foot can touch the ground, and if the bending speed is too fast, you can intervene with the foot to increase the friction. However, this situation is clearly a forced approach. In order to adjust the forward trajectory of the snowmobile, the side pressure of the body can play a certain role. At the bottom of the snowmobile are 2 ice blades, and when moving normally, the human body is pressed in the middle, and the friction of the 2 ice blades is the same. If you want to move to the right, press the body to the right, increase the friction of the right ice blade, so that the left side is fast and the right side is slow, and the right side is biased to the right.
Force Map
The left and right rotation of the head can also interfere with the forward trajectory of the snowmobile, the head rotates to the right, then due to the conservation of momentum, the foot will rotate to the left, so as to achieve the effect of right turn, if the weight of the helmet is a little larger, it can even do the action of flicking the tail, and realize the possibility of high-speed turning. As mentioned earlier, the speed of the snowmobile is very fast, so a little change in the athlete's control is enough to change the trajectory of the snowmobile. This requires athletes to have good control and judgment. In addition, in order to obtain faster speed, the influence of air resistance can not be ignored. Wind tunnel proven helmet with reduced drag coefficient. And the tall athletes suffered a loss due to the windward area conference.
Conservation of angular momentum
4. Win the gold black technology
As mentioned earlier, the most critical part of the steel frame snowmobile project is the 50m acceleration in the departure stage. Yin Zheng's track starting record also has a focus on learning black technology behind it. At the departure stage, it is relatively easy to appear "pulling and deceleration", and the scientific research team of Beijing Polytechnic University analyzes the movement status of athletes and snowmobiles through high-speed cameras and sensors, so as to provide data for training and avoid pulling and deceleration. In addition, the taxiing stage can also analyze the snowmobile track through the obtained data, providing a basis for athletes to control the snowmobile and find the optimal way forward.
North Polytechnic research team
5. Summary
Therefore, the seemingly lying flat steel frame snowmobile, this time can achieve a breakthrough of 0, won the bronze medal, behind the data analysis of the scientific research team, inseparable from the precise control of athletes, but also inseparable from the usual hard training.