Can trains really replace airplanes? If there is a hyperloop, it is indeed possible!
Nowadays, high-speed rail has been extended to many parts of the mainland, and people's travel across provinces and cities is becoming more and more convenient. High-speed rails with a speed of more than 300 kilometers per hour make traffic faster and faster. However, the mainland land is too vast, the distance between many major cities has reached thousands of kilometers, and the speed of high-speed rail still seems to be somewhat slow, and it is far less than that of airplanes.
In the future, this problem may be solved, because scientists are thinking about a shocking concept – hyperloop.
Hyperloop definitely lives up to the word "super". According to scientists' estimates, its speed can even exceed 1600 kilometers per hour! What is this concept? Let's put it this way, the circumference of the earth is only about 40,000 kilometers, and if there is a hyperloop, it will only take a little more than a day to circle the earth!
This does sound a bit amazing, why can hyperloop be so fast?
You may not believe it, but hyperloop actually solves a problem that everyone knows - air resistance.
You may think that air resistance is an inconspicuous problem, but you are wrong to think so. Even for ordinary people, when the wind speed exceeds level 6, it is already more difficult to walk in the wind. In the 100-meter race, when athletes create good results in the case of class 3 winds, sometimes they will not be recognized as records, which shows that the influence of air on the speed of movement is very large.
A little faster, we can see that in F1, the cars are all made into a streamlined shape and very low, also to minimize the air resistance encountered during the race.
For trains, air resistance is also a huge obstacle, which greatly limits the operating speed. The air resistance faced by the train in operation has such a formula -
Wherein, C is the air resistance coefficient, ρ is the air density, S is the windward area of the object, and V is the relative movement speed of the object and the air. That is to say, if the speed of the train is increased to 2 times the original, then the air resistance will become 4 times. If you really want the train to reach a speed of 4,000 kilometers per hour, then it encounters 1,000 times the air resistance of the 400 kilometers per hour train!
The presence of air not only creates a huge resistance, but also brings another problem, that is, aerodynamic noise. You know, in a dense atmosphere, aerodynamic noise will increase sharply to the 7th or even 8th power as the speed increases! That is to say, if the problem of air resistance is not solved, even if it can run very fast, people's ears will be deafened.
The researchers pointed out that when the speed of the train reaches 300 km / h, its aerodynamic resistance has accounted for about 80% of the total drag, and the aerodynamic noise generated by its operation will exceed the wheel rail noise. In other words, can our high-speed rail be any faster? Theoretically yes, but in practice it is not feasible. If the problem of air is not solved, the maximum speed of the human train will be difficult to break through.
From another point of view, according to the speed of 300 kilometers per hour, if it can really run in the vacuum pipe, then the train can face 80% less resistance, which can greatly save energy and costs! Some people have even done calculations that vacuum pipes can reduce the energy consumption of transportation by 98%.
In addition to air resistance, another problem that trains need to solve is frictional resistance. This is not too much of a problem, after all, maglev trains have been in use for many years now. Therefore, the so-called "hyperloop" is actually a vacuum pipe + maglev train, it is not based on the current high-speed rail upgrade, so the hyperloop can only be used as a nickname for vacuum pipeline transportation, can not reflect its essence.
Different scientists have given different theories about the speed of vacuum pipe traffic.
In 1904, Robert Goddard, the father of modern rockets, first proposed the concept of vacuum pipe transportation, and his estimation at the time was that in vacuum pipes, the speed of maglev trains could reach 1600 kilometers per hour!
In 1934, the German Hermann Kempel calculated a slightly smaller result, believing that the maximum speed of such a train was about 1,000 kilometers per hour, which was also much faster than the current civil airliner (800-900 kilometers per hour).
By the 1960s, researchers at the Massachusetts Institute of Technology in the United States had also conducted studies in this area, and the results were much more astonishing. They believe that in a high vacuum pipe of 1.01325 kPa (1/100 of the atmospheric pressure), the maglev train can reach 22500 kilometers per hour! You know, it doesn't take 2 hours for this speed to circle the earth! Moreover, the speed of the first universe is only 28440 km / h, and the vacuum pipeline traffic is really fast enough to fly.
You may ask: even if it is fast, it can't cross the ocean, right?
Not necessarily, because someone has even proposed the technology of undersea vacuum pipes. If this technology is really successful, it can really replace airplanes to a large extent!
Although vacuum pipe traffic has such an amazing speed, we are indeed very far from its inception.
If nothing else, the cost alone is staggeringly high. Professor Zhao Yong of Southwest Jiaotong University once pointed out that the investment in vacuum pipeline transportation should at least refer to the cost of the subway, that is, 6-1 billion yuan. Even if it is to build a vacuum pipeline with a length of 1,000 kilometers, it will cost nearly 1,000 billion yuan! It can be seen that the development of human science and technology is really to match the economic development, without a strong economic foundation, many scientific breakthroughs are difficult to achieve.
In addition, in terms of technology, we also face many difficulties. First of all, thousands of kilometers of vacuum pipes, how to extract air to achieve a high vacuum, which is a technical problem for current human beings. Secondly, hyperloop needs to use linear traction technology, but the efficacy of this technology cannot meet its power needs and needs to be improved. In addition, the current magnetic levitation technology is not stable enough for hyperloop.
Including elon Musk, who is known as a technology maniac, in 2013, he also admitted that he was very optimistic about the future of "hyperloop". But even Musk, who claims to have 500,000 people on Mars by 2050, does not dare to personally form a team to conduct research on this technology, but only calls on people of insight to conduct research in this area.
In 2016, there was a relatively good project that was experimented with, that is, Hyperloop One. During the experiment, an experimental car accelerated to 643 km / h in less than 2 seconds in the desert of Las Vegas, USA. While the project subsequently secured funding from Virgin Galactic, not many new breakthroughs have been heard in recent years.
Shen Zhiyun, academician of the Chinese Academy of Sciences and the Chinese Academy of Engineering, also pointed out that although there is research value, vacuum pipeline transportation technology is still difficult to achieve.
It can only be said that "hyperloop" is still a development trend, with research value and market, we look forward to this day. However, in the short term, we may be difficult to see this technology enter real life, or rest assured to take the ordinary high-speed rail.