In 1920, Feng Tianming met Yang Shuoming, who had a profound influence on him, and he was invited to participate in the army rocket test team organized by Yang Shuoming to develop liquid-fuel rocket thrusters.

Because rocket weapons played an important role in the two wars of resistance against Japanese aggression, with the efforts of Yang Shuoming, the Chinese Army set up a rocket test team, and Feng Tianming, together with experts in China, set up a research group on this basis, and set up a rocket flight field in an abandoned arsenal to conduct rocket research and testing. They overcame the difficulties of China's weak domestic research base, and convinced the rich and skilled to support their rocket technology career with their fascinating space flight. Later, with the strong funding of Yang Shuoming, this group established the current "China Rocket Association".

Soon after the establishment of the Rocket Association, they successfully tested a number of "Wanhu" small rockets. In the summer of 1921, Feng Tianming visited the Federal Institute of Technology in Zurich, Switzerland. It was here that he met Shen Wang, an American medical doctor. Feng Tianming believed that future astronauts would have to withstand great acceleration, so the two of them conducted a series of space medical experiments together. They fixed the mice to a flat wheel, then turned the wheel faster and faster until it reached the limit, and then killed the mice for dissection. In the end, they concluded that the limiting factor for the acceleration of gravity in the mouse was its brain, and that the cause of death in the mouse was mostly cerebral hemorrhage. The results of this experiment have caused quite a stir in Chinese and foreign academic circles.

In the spring of 1922, Feng Tianming, who returned to China, taught at the newly established Yenching Institute of Aeronautics and Astronautics with a doctorate in aeronautical engineering. On the one hand, Feng Tianming was teaching at the academy, and on the other hand, the army and large civilian enterprises provided research funds, and continued to conduct experiments and research in the Rocket Association. After continuous experiments and summaries, Feng Tianming wrote a paper on various aspects of the theory and experiment of liquid-propellant rocket engines, in which the young Feng Tianming tried to analyze and measure the complex problems of jetting, atomization, combustion, dissociation, gaseous equilibrium, and expansion phenomena that occur in rocket engines, and explored and elaborated on these problems.

At that time, liquid-propellant rockets were a novelty, while solid-fuel rockets existed hundreds of years ago. Tsiolkovsky, a Russian aerospace theorist, and Obert, a German scientist, have both pointed out that liquid propellants have great potential to produce stronger thrust. The main goal of Feng Tianming and his rocket research team is to put these recommendations into practice. The work of Feng Tianming and others is to provide methods and answers to the problems of ignition, mixing, cooling, and controlling violent combustion of rockets, and to combine the engine and fuel tank of liquid fuel into a carrier vehicle and launch it into the sky. For example, today's test launch of the "Wanhu 5" liquid-fueled rocket (fueled by a mixture of gasoline and liquid oxygen) is the most successful experiment in recent times.

Just as Feng Tianming and his partners were inspecting the wreckage of the rocket, a car appeared in the launch site, and two people in black suits and bowlers jumped out of the car.

"Dr. Feng Tianming?" A man in black looked at the young scientist, who was only 27 years old, and asked.

"I am." Feng Tianming looked at the stranger standing opposite and replied.

"I have some documents for you here, please sign for them." The man in black nodded, took a large file box, handed it to Feng Tianming, and handed him a signed slip at the same time.

"What is this?" Feng Tianming looked at the file box with some vigilance and asked.

"Here are some materials that will help you in your research." The man in black seemed to understand Feng Tianming's thoughts, and as he spoke, he opened the file box and flipped through the neatly stacked thick documents inside, indicating that there were no bombs or other suspicious items in it.

Feng Tianming's gaze fell on a drawing with various pipes, and he couldn't help but breathe. At this time, he no longer doubted the real surname of the content of these documents, but couldn't wait to sign his name on the form. Probably because of the excitement, his hands trembled a little.

It was no surprise that a scientist like him behaved like this, and the corner of the black-clothed man's mouth showed an imperceptible smile, he took back the sign, nodded to Feng Tianming and the others, and then turned to leave.

At this time, Feng Tianming did not notice that the other party had left, and his attention had all been focused on the drawings and the data on them in the Chinese box in his hand.

"Who are these people? Why should you be given this? Dawn? A colleague from the Rocket Association asked curiously.

Listening to his question, Feng Tianming was stunned for a moment, and then came back to his senses. He realized that he hadn't even asked who had given him these valuable information, and he couldn't help but smile bitterly.

"It doesn't matter who they are." There was irrepressible excitement in Feng Tianming's voice, he didn't think much about the identity of the other party, but beckoned and let everyone gather around.

"'How does a liquid rocket engine work'? Who wrote this? ”

"This is said to be written by a deceased old scientist Ding Wenxiang......"

"The author's surname is Ding? Isn't it Ding Gongchen's descendant? ”

Listening to the discussions of his colleagues, Feng Tianming's excited heart gradually calmed down.

He knew that he needed a little time to digest this valuable research material with everyone.

"Let's clean up the site first, finish today's work, let's go back and study these things together." Feng Tianming said.

In the evening, Feng Tianming, who had been busy all day, still did not rest, he sat at the table, carefully reading the valuable information obtained during the day under the electric light.

“…… Liquid rocket engine refers to a chemical rocket engine with liquid propellant. Commonly used liquid oxidants are liquid oxygen, nitrous tetroxide, etc., and combustion agents are liquid hydrogen and kerosene. Oxidizer and incendiary agent must be stored in separate tanks......"

"Liquid rocket engines generally consist of a thrust chamber, a propellant supply system, and an engine control system."

"The thrust chamber is an important component that converts the chemical energy of a liquid propellant into propulsion. It is composed of propellant nozzle, combustion chamber, nozzle assembly, etc., the propellant is injected into the combustion chamber through the injector, and is vaporized, evaporated, mixed and burned to generate combustion products, which are flushed out of the nozzle at high speed to generate thrust. The pressure and temperature in the combustion chamber will be quite high, so cooling ...... will be required."

“…… The function of the propellant supply system is to deliver propellant to the combustion chamber at the required flow rate and pressure. According to different conveying methods, there are two types of supply systems: extrusion type and pump type supply. The extrusion supply system uses high-pressure gas to enter the oxidant and combustion agent storage tank after being depressurized by the pressure reducer (the flow rate of oxidant and burner is controlled by the pressure adjusted by the pressure reducer) and extrudes them into the combustion chamber respectively. The extrusion supply system is used only for small thrust engines. High-thrust engines use a pump-type supply system, which uses a hydraulic pump to deliver propellant......"

"The function of the engine control system is to regulate and control the working procedures and working parameters of the engine. The working procedure includes three stages: engine starting, working and shutdown, and this process is carried out automatically according to the predetermined procedure. The working parameters mainly refer to the thrust and the mixing ratio of the propellant. ”

"The advantages of liquid rocket engines are high specific impulse, large thrust range, repeated starting, control of thrust, long working time, etc."

“…… The above experimental data show that the liquid rocket engine will be the mainstream of space launch in the future, and its structure is much more complex than that of the solid engine, mainly composed of an ignition device, a combustion chamber, a nozzle, and a fuel delivery device. The ignition device can use a gunpowder igniter, for the upper stage engine that needs to be started multiple times, a plurality of gunpowder igniters are required, the combustion chamber is the place where the liquid fuel and oxidizer burn and expand, in order to obtain a higher specific impulse, it generally has a high pressure, even if it is an ordinary engine, there is usually a pressure as high as dozens of atmospheres. Combustion at high pressure is more complex than at normal pressure, and as the volume of the combustion chamber increases, the combustion instability becomes more and more serious and more troublesome to solve. At present, there is no reliable mathematical model to analyze the problem of combustion stability, and it is mainly solved by a large number of engine combustion tests. In repeated combustion tests, the parameters of the engine are continuously optimized to alleviate the unstable combustion phenomenon. However, the unstable combustion phenomenon of the engine with low room pressure and small thrust is not obvious, and unstable combustion is one of the main problems restricting the thrust increase of liquid engine. The combustion chamber of a liquid rocket engine is cooled by liquid fuel or oxidizer, which flows through the combustion chamber wall to cool down before entering the combustion chamber. The nozzle of the liquid engine is also a Laval nozzle, and the expansion section is generally bell-shaped, but the cooling nozzle is used, which is cooled by liquid fuel or oxidizer. ”

"After several tests, it has been determined that there are four modes of liquid engine fuel delivery: extrusion cycle, gas generator cycle, staged combustion cycle, and expansion cycle."

"Extrusion and recycling of high-pressure gas through the pressure reducer depressurization into the oxidant, combustion agent storage tank, which is squeezed into the combustion chamber respectively, subject to the material of the storage tank, it is impossible to achieve much pressure, so it is only used in small low-energy engines."

"In the gas generator cycle, a part of the fuel and oxidizer flows through a gas generator, and after combustion, the fuel pump and the oxidizer pump are pushed, and the fuel pump and the oxidizer pump are pressed into the combustion chamber, and the pre-ignited exhaust gas is directly discharged. The initial flow of fuel and oxidizer is either through the extrusion of the storage tank or guided by natural gravity. ”

"The staged combustion cycle is also known as the re-ignition method, which is also the combustion of fuel and oxidizer in the pre-burner, pushing the fuel pump and the oxidizer pump, but the difference is that the gas in the pre-burner is not directly discharged, but pressed into the combustion chamber, so as to avoid the waste of fuel and oxidizer, and can achieve a greater specific impulse. In order to pursue a higher specific impulse in the pursuit of higher specific impulse, the general combustion chamber pressure is much higher than that of the gas generator cycle, also known as the high-pressure refueling method. ”

"The expansion cycle is that the fuel or oxidizer flows through the combustion chamber wall and the nozzle wall, where the combustion chamber and the nozzle are cooled at the same time, and the self-heating has a greater pressure, which pushes the fuel pump and the oxidizer pump to operate. Generally speaking, the engine of the expansion combustion cycle has a high specific impulse, which is theoretically the highest when other conditions are equal, but the test has proved that it is difficult to increase the thrust. ”

"The way the liquid engine circulates and the chamber pressure and nozzle design of the combustion chamber have a lot of influence on the specific impulse value, but it is the liquid fuel that has the most impact on the specific impulse of the engine. The higher specific impulse is kerosene fuel and alcohol fuel, the main feature is that it is cheap, and at the same time non-toxic, suitable for liquid engine use......"

After Feng Tianming finished reading this article titled "The Working Principle of Liquid Rocket Engines", he let out a sigh of relief.

"I can't imagine that someone has summed up so many valuable experiences earlier."

Feng Tianming said to himself, a look of disbelief involuntarily appeared on his face.

It was hard for him to imagine that someone would have conducted so many experiments so early and summarized so much valuable data and information.

It's just that he doesn't know now that these things were by no means written by his ancestors.

On the same night, in another corner of Yanjing City, a person was just like him, writing something quickly under the lamp.

"It's too late, isn't the general resting?" Xi Xue saw Yang Shuoming stop writing, as if he was distracted there, and couldn't help but say behind him.

"I'll have to wait a while, if you're sleepy, go to sleep first, you don't have to accompany me." Yang Shuoming looked back at her and said with a smile.

Xi Xue seemed a little angry when she saw that he had no intention of resting, and she stepped forward to his side and took some of the manuscripts he had just written in front of her and looked at them.

"Today, I would like to talk to you about a problem that I have been thinking about recently, that is, the issue of talent development. What I want to talk about is not the cultivation of ordinary talents, but the cultivation of scientific and technological innovation talents. I believe that this is a big issue for the long-term development of our country. ”

"Today, both the political axe and the non-governmental attach great importance to the issue of scientific and technological innovation, and invest a lot of money in 'innovation projects', 'innovation plans' and so on, which is necessary. But I think it's more important to have people with innovative ideas. The problem lies in the fact that at present, there is not a single university in China that can run a school according to the model of cultivating scientific and technological inventions and creative talents. In my opinion, this is a big problem in China right now. ”

"Recently, I read the American magazine "Silk Language", and when I saw the situation of the Massachusetts Institute of Technology in the United States, it reminded me of my education at the Massachusetts Institute of Technology in the United States."

"The Massachusetts Institute of Technology was also a famous name at the time, but I didn't think it was a big deal, and I got a master's degree in one year, and my grades were top-notch. In fact, I didn't learn anything innovative this year, it was very general. But in Massachusetts, innovation permeates the entire campus, and it can be said that innovation is one of the spirits of the whole school. Here, you have to think about things that others have not thought of and say things that others have not said. There are a lot of top talents, and I have to compete with them to be on the cutting edge. Innovation here can't be ordinary, you can't take small steps, and you'll soon be surpassed by others. What you think and do must be a lot higher than others. The academic atmosphere there is very strong, and the academic seminars are very lively, inspiring and promoting each other. It's good for us now, some technical and academic seminars are still kept secret from each other and blocked from each other, which is not the style of study for the development of science. If you really have the ability, you won't be afraid of others catching up. So when I went to MIT, my brain was enlightened, and I talked about all the things I had never thought of before, and the content was at the forefront of scientific development, which opened my eyes. ”

"In Massachusetts, I studied mechanics, but my teachers encouraged me to learn all kinds of useful things. I went to the physics department to listen to lectures, and they talked about the frontiers of physics. The Department of Biology can hear the latest tutorials on genetics. I also listened to the lectures in the chemistry department, and the lectures were also about the frontiers of chemistry. I attended the colloquia of the Department of Chemistry, and I was not at all excluded. There are many masters at MIT, and there is no shortage of strange people with strange surnames, who never follow the crowd, dare to think what others dare not think, and do what others dare not do. Everyone said that good things, in his opinion, were very ordinary, nothing. That's why I say, how can there be innovation without this spirit! ”

"MIT provides these scholars and professors, as well as young students and graduate students, with full academic power and an open cooking atmosphere. Different schools of thought and different academic views can be fully published. Students can also fully express their different academic opinions and challenge the authorities. I've talked in the past about my graduate student at MIT debating with some of the authorities, but that's a common occurrence in the school. The academic ethos at MIT is bright and vibrant. It was very instructive and eye-opening for us young people to study here. What university in our country can do this? Everyone was polite when they met, and the academic discussion was not lively. How can this nurture innovative talent? Not to mention the masterful talent. ”

Interestingly, MIT also encourages those who are science and engineering students to improve their artistic literacy. I remember that many of the leaders of the research groups at that time were studying painting while researching topics, and some of them went on to become famous abstract painters. My teacher, Professor Dickert, was very happy when he heard that I knew how to learn about painting, music, and photography, and that I had been accepted as a member of the American Academy of Arts and Sciences, and he said that it is important that you have these talents, and that you are better than me in this area. ”

(To be continued)