#头条创作挑战赛#
Text/Zhan Hai
According to the Global Times, on April 28, China's self-developed 130-ton liquid oxygen kerosene engine completed a four-engine parallel ignition test, with a total thrust of more than 500 tons during the test, setting a record for the largest ignition test on a liquid fuel engine in China. This also means that China is one step closer to completely solving the key power problem of large rockets.
(Tail flame from a rocket engine with a thrust of more than 500 tons)
The liquid fuel engine in this test is a relatively special engine, which adopts the mode of "pump back swing", that is to say, the swing device of the engine is placed behind the engine, and the swing of the engine nozzle is relatively better controlled. Placing the rocker in the rear also frees up more working space for the engine and lightens the engine's mechanics. Of course, so many advantages are not in vain, this pump swing mode has high requirements for the strength of the swing device, especially the ability to resist high temperature and high pressure, before the 120-ton liquid fuel engine this system has not been equipped, indicating that the key technology has not been "eaten", and on the 130-ton equipment, this technology has begun to be used, which also shows that this technology should have been completely broken through in the recent period of time, and applied to the new rocket engine.
(4 units in parallel can get stronger thrust)
After breaking through this technology, it is more complicated to operate in parallel with four engines, although from the appearance, it is simple to "bundle" the four engines, but in terms of operation, it is necessary to synchronize the operation of the four engines, and the thrust provided is also synchronized accordingly, which is not easy in the operation process, although the mainland has successfully used this technology before, and most of the first stage thrusters of the Long March series of rockets have used this kind of parallel engine, but the difficulty of connecting four 130-ton rocket engines in parallel is still very high.
(Four-machine parallel ignition test)
Since it is difficult to connect parallel engines, why doesn't the mainland directly promote the research and development of a single large rocket engine? In fact, the reason is simpler, and there is a positive correlation between the thrust of a rocket engine and its size, but it does not mean that if you want a high-thrust engine, you can directly enlarge the parts of a small-thrust engine. High-thrust engines require much higher technology and operation than small-thrust engines, which not only require higher sealing grades, material compression and heat resistance levels, but also have much higher R&D costs than multiple relatively small engines in parallel.
(The most powerful liquid-fueled engine in human history, the RD-170)
Therefore, if China wants to rapidly increase the thrust of liquid fuel engines, it is necessary to use a two-pronged approach, on the one hand, to continuously promote the research and development of higher thrust liquid fuel engines, and on the other hand, to strengthen the number of parallel rocket engines and the operation of rocket engines. Taking the American "Falcon-9" heavy rocket as an example, the rocket directly connected nine "Merlin" engines with a thrust of 69 tons in parallel, and obtained a greater thrust than the four 130-ton rocket engines we tested in parallel.
(The Falcon-9 rocket has 9 "Merlin-1D" engines connected in parallel)
At present, China's ability to connect four 130-ton rocket engines in parallel is close to the advanced level of foreign countries. Although in terms of thrust, it is not as strong as the RD-170 liquid fuel engine in human history, but the single thrust of RD-170 is greater than our existing 130-ton thrust liquid fuel engine.
(The legendary "Long March 9" heavy rocket)
At present, these four large engines with a thrust of more than 500 tons in parallel, considering their relatively large size, cannot be ruled out that they will be used in the mysterious "Long March 9" heavy-lift carrier rocket with a core diameter of 10 meters in the future, so as to output surging power for China's manned landing on the moon.