Recently, the South China Morning Post disclosed a news that shocked the international military science and technology community, revealing the root cause of the repeated test launches in the process of developing hypersonic weapons in the United States. According to reports, in a paper published in the "Aerodynamics News", Chinese scientists pointed out that the hypersonic aerodynamic simulation and analysis software developed by NASA - Vulcan-CFD may have a fatal calculation flaw, this discovery has made many netizens worry: "Why is such a top-secret level of research results made public, why not let the United States continue to explore on this road and find no north?"
Hypersonic technology has long been regarded as the highland of global military science and technology competition, and China, Russia and other countries have made remarkable achievements in this field, such as Russia's hypersonic missiles have shown excellent performance in actual combat. At the same time, North Korea and Iran also claim to possess hypersonic missile technology, and North Korea even successfully test-fired the Hwasong-16B hypersonic missile, which has the characteristics of wave-riding body gliding. However, it is quite surprising that in this hypersonic race, the United States, which started the earliest and invested the most, has never been able to break the cycle of failed test launches.
It turns out that the problem that has plagued American scientists for a long time is precisely the answer that Chinese scientists have found in their in-depth research. In a paper published in the Journal of Aerodynamics on March 14 this year, the research team led by Professor Liu Jun revealed that the Vulcan-CFD software ignores a link in the complex equation of high-temperature ablation when simulating hypersonic flight, which may be a key factor in the frequent failure of US hypersonic weapons test launches.
Under hypersonic flight conditions, the air in front of the aircraft cannot sense the presence of the aircraft through the compressed air flow, which will form a strong shock wave at the front of the fuselage, and the shock wave energy is huge, causing extremely high temperatures at the nose cone. This requires the aircraft to use high-temperature resistant materials here to resist the effects of aerodynamic heating. However, the materials here must not only be resistant to high temperatures, but also have wave- and light-transmitting characteristics to accommodate optoelectronic systems such as communication antennas, radars, infrared and visible light detection equipment, and thus meet the needs of missile guidance and communication. To this end, researchers creatively proposed the use of "sweating materials" to deal with the challenge of high-temperature ablation, that is, to coat the surface of the wave-transmitting material with components that can quickly evaporate at high temperatures and take away heat, so as to protect the missile head and its wave-transmitting fairing. Of course, with advanced material technology, China and other countries have developed high-performance materials that are resistant to high temperatures, transmit waves, and do not require "sweating", simplifying the structure and reducing weight.
However, even with the best materials, simulation software is still needed to accurately analyze the high temperature distribution, diffusion range, and possible maximum temperature of the nose cone of the aircraft in a hypersonic environment. This is where Vulcan-CFD comes in, developed by NASA's Langley Research Center's Hypersonic Aspiration Propulsion Unit and widely used in the analysis of most of the world's wind tunnel experiments, to simulate continuous flow fields from subsonic to hypersonic speeds, including chemical and thermal non-equilibrium processes, as well as a variety of turbulence models, designed to provide detailed and accurate data support.
Unfortunately, the research of Professor Liu Jun's team found that Vulcan-CFD has serious shortcomings in processing the details of hypersonic flow fields, and the simulation analysis of aircraft surface chemical composition and temperature changes is not accurate enough, which undoubtedly has a huge negative impact on engineers who rely on the software for aircraft design and analysis. In short, because the software fails to accurately reproduce the harsh environment that the hypersonic fairing actually faces, the fairing designed based on this simulation requirement is prone to unexpected high-temperature airflow impact in specific "weak" areas during flight, which will lead to the failure of the wave transmission function, and may even lead to serious consequences such as loss of communication and even loss of control and crash, which also explains why the US hypersonic weapons program has been frequently frustrated.
Faced with such a question, one cannot help but ask: if the Vulcan-CFD software has such a wide influence, why has China's hypersonic technology research and development not been affected by it? The answer may be quite ironic: due to the technological blockade imposed by NASA on China, Chinese researchers have cleverly avoided this "trap" by not using this software, but developing their own test software. Although the Vulcan-CFD software enjoys a high level of authority in the world, the negligence in processing critical data has led to the stagnation of hypersonic technology in the United States, and NASA's reputation has been tarnished.
What is particularly noteworthy is that the three major hypersonic weapons programs currently in service in the United States - LRHW, ARRW gliding hypersonic missile and HAWC air-breathing hypersonic missile have repeatedly failed during the test launch process, so that Internet public opinion is hot about it, and the comments of netizens are also full of ridicule and helplessness. The test launch records of the LRHW and ARRW missiles can be called a "history of blood and tears", and almost every test launch is accompanied by failures of varying degrees, which has hit the confidence of the US military.
As for why Chinese scientists chose to make this major discovery public, many netizens have questioned whether this constitutes a kind of technical leakage? It is true that although the paper does not directly provide specific numerical data, for NASA, which has accumulated rich experience in the field of hypersonic speed, this hint undoubtedly provides an important clue for it, and is likely to lead to the innovation and upgrade of the Vulcan-CFD software. Nevertheless, some people believe that this move objectively delays the time for the United States to master hypersonic technology and increases its R&D investment, in a sense, it can be regarded as a strategic opportunity for China.
In short, the paper of Chinese scientists revealing the reasons for the failure of US hypersonic weapons has attracted widespread attention and discussion, on the one hand, it demonstrates the mainland's scientific research strength and innovative spirit in related fields, and on the other hand, it also adds new suspense to the development of global hypersonic technology. However, no matter what the outcome, the pace of scientific and technological progress will never stop, and the competition and contest between China and the United States in the field of hypersonic weapons research and development will continue to be staged.