This facility will test revolutionary new modes of transportation…and next-generation weapons, much to the chagrin of the United States.
According to the South China Morning Post, Chinese engineers have just completed the construction of a record installation: the most powerful hypersonic wind tunnel on the planet is now operational. This is excellent news for Chinese aeronautics and ballistics… and a little less so for the United States, which will certainly not see this news very favorably.
A wind tunnel is a large installation that allows the aerodynamic properties of an object to be tested. This makes it possible to study the flow of air around an object, and by extension to measure the mechanical stresses with a degree of precision unattainable in real conditions.
In practice, this device called JF-22 takes the form of a long tunnel 4 meters in diameter. An already impressive figure; by way of comparison, NASA’s Langley Center hypersonic tunnel, one of the most efficient in the world, is only 80 centimeters in diameter. This space will allow researchers to test relatively large devices. In some cases, they may even avoid using a scale model, as is often the case in these wind tunnels.
Winds at Mach 30
The other very important metric in this context is airflow velocity. And that’s where this JF-22 gets really impressive. According to the latest technical tests conducted on May 30 by the Institute of Mechanics in Beijing, it can generate winds that reach an absolutely incredible speed of… 10 km per second, or Mach 30. This corresponds to 30 times the speed sound in the air.
To achieve this, the researchers used a very original method. As this article from Virginia Tech University explains, traditional hypersonic wind tunnels typically use a pressure differential. Engineers introduce a very high pressure gas into a very low pressure chamber, which generates hypersonic flow as the laws of physics attempt to balance the pressure. Jiang Zonglin, the team leader who designed the JF-22, opted for another method. According to the SCMP, they used… explosions.
The detonations all generate a shock wave; the impact one feels is produced by the collision between the high pressure wavefront and another surface. Very commonly, when two wave fronts cross, they can “bounce” off each other. It is this phenomenon that Chinese researchers have exploited. Still according to the SCMP, their idea is to generate explosions with a precise timing so that all these shock waves focus on the same point. The energy thus produced makes it possible to accelerate the air to a gigantic speed to supply this wind tunnel.
Hypersonic flight, an immense challenge
If China decided to build such a facility, it is because hypersonic flight represents a colossal engineering challenge. Below Mach 5, the air can generally be considered incompressible, which greatly facilitates the design. But beyond that, the fiction of the device with the air generates shock waves and very violent temperature variations. Any hypersonic device is exposed to dantesque mechanical constraints. It is therefore very difficult to design a machine with sufficient structural integrity.
But this is only the visible part of the problem. Beyond these essentially mechanical considerations, it is also necessary to take into account a large number of chemical reactions. Under the conditions of hypersonic flight, the temperature and pressure are so great that the air molecules are downright shredded; we are talking about dissociation. The atoms thus torn off can recombine to form other chemical species, which can in turn alter the behavior of the device.
This facility will allow Chinese researchers to study these phenomena on lots of prototype hypersonic machines. In the context of aviation, this term generally refers to all devices capable of flight beyond Mach 5, five times the speed of sound. There are already many examples, but this technology is still far from being fully mastered.
Its development is one of the priorities of the Chinese government. Citing Xi Jinping’s official party roadmap, the SCMP explains that the goal is to democratize hypersonic flight by 2035. By that date, program officials hope to be able to deploy an entire fleet of aircraft capable of reaching any point on Earth in less than an hour, or sending thousands of people into space each year.
But civil aviation and aerospace are not the only areas that could benefit from this technology. If it is considered highly strategic, it is because it can also be used to build a new generation of weapons of mass destruction, starting with hypersonic missiles that are extremely difficult to intercept. And this point in particular is already a major source of friction on the international scene.
An eminently strategic technology
China has been working on these weapons of this category for several years – much to the chagrin of its best enemy Uncle Sam, who has already invested a lot of resources in this technology. The US government has already condemned the Chinese hypersonic missile tests on several occasions, for obvious reasons: they pose a clear threat to military supremacy which is very close to its heart.
And the more development advances, the more the tensions become palpable, especially in the current geopolitical context. Because even if this theme has become a bit more discreet lately because of the invasion of Ukraine by Russia, the situation remains extremely tense around Taiwan.
For example, in recent weeks there has been much discussion in the US and Chinese media about the deployment of a sizable US naval force around the island, caught in the middle of a diplomatic standoff between the two countries (see this Reuters article ). However, last month, the SCMP reported that Chinese scientists had conducted a simulation of an American aircraft carrier strike… using hypersonic missiles.
If an open war between the two nations is fortunately not yet on the agenda, this episode clearly shows the importance of hypersonic flight in these balances of power. We therefore imagine that the entry into service of the JF-22, which is just wide enough to accommodate a prototype hypersonic missile, will be viewed with a dim view by the Pentagon.
It will therefore be necessary to follow the development of these technologies carefully, in particular among the Chinese and the Americans, because this theme could condition part of the diplomatic relations between the two superpowers – with all that this implies for the rest of the international community. .
