Original title: Why the 26 seconds that made Yang Liwei “unbearable” no longer bother today’s astronauts
On October 16, the Long March 2 F Yao 13 carrier rocket successfully launched the Shenzhou 13 spacecraft, and the China Space Station ushered in a new “space travel trio.” The live TV footage showed that the three astronauts were more relaxed when they lifted off.
Such a relaxed picture reminded Chang Wuquan, the chief designer of the Long March 2 F-Yao 13 carrier rocket of the First Academy of China Aerospace Science and Technology Corporation, of the 26 seconds “unbearable” experienced by China’s first astronaut Yang Liwei to enter space. In the article “A Day in Space”, Yang Liwei recalled, “The painful feeling is getting stronger and stronger, and the internal organs seem to be broken. I can hardly bear it and feel that I am going to die.”
Chang Wuquan told reporters that the source of Yang Liwei’s “unbearable” is resonance, which was once a world-class space launch problem. Not only the rockets developed by China have this problem, but also foreign rockets. As early as the 1960s, during the launch of the American Hercules rocket, there was a vibration that lasted 30 seconds. French rockets have experienced similar problems, which affected the lifespan of satellites.
How to make Chinese astronauts no longer suffer such pain and eliminate the hidden danger of rocket failure? After calculation and analysis, testers from the Beijing Institute of Strength and Environment, affiliated to the China Aerospace Science and Technology Corporation, believe that the “root of disease” may be in the oxidizer. When the vibration frequency of the fuel in the oxidizer is close to the vibration frequency of the rocket structure, it is likely to be A divergent vibration that couples the structure and the liquid occurs.
After the theoretical analysis, the test personnel of the institute then carried out the full arrow modal test and the liquid characteristic test of the oxidant pipeline. During the test, the tester first injects fuel into a fuel pipe, and then loads the fuel pipe with vibrations of different frequencies to observe the vibration frequency of the fuel. If the laboratory data is consistent with the full-arrow modal test data, it can prove that the tester’s inference is correct.
After more than half a year of investigation, analysis, and calculations, the testers finally concluded that the problem was that the rocket produced a kind of divergent vibration-POGO vibration. This conclusion confirmed their previous speculation.
Chang Wuquan said that after finding the root cause of the problem, the research team of the First Academy made improvements. Originally, the booster accumulator of the Long March 2 F Yao 5 launch vehicle was equipped with two bellows. When, the bellows is reduced to one. This improvement has achieved obvious results. When the Long March-2 F Yao-6 carrier rocket launched the Shenzhou-6 manned spacecraft, the vibration magnitude and vibration time were reduced, and the astronauts reported that the vibration was much lighter.
“Much lighter” means that the research direction is right, but the problem has not been completely solved.
Chang Wuquan told reporters that the R&D team continued to optimize the design and changed the booster accumulator to a “variable energy accumulator”, and used accumulators with different PV values during different flight periods. The device can absorb fuel vibration. The generated energy changes the vibration frequency of the fuel, and the rocket no longer produces POGO vibration.
After the Long March 2 F Yao 7 carrier rocket launched the Shenzhou 7 manned spacecraft, astronaut Nie Haisheng responded, “The rocket we are riding on is very comfortable, and there is almost no vibration.”
A short sentence means that the First Hospital has overcome the problem of resonance.
“The safety of astronauts’ lives when flying into space is closely related to the rocket. From the’unbearable’ 26 seconds to’almost no vibration’, behind this is the rigorous analysis, long-term efforts and continuous breakthroughs of the rocket development team.” Chang Wuquan said.
China Youth Daily·China Youth Daily reporter Qiu Chenhui, trainee reporter Yang Jie Source: China Youth Daily
Version 08 on October 18, 2021
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