This star is going to the moon

Chapter 26 Solving the Long March Rocket's Heart Problem
Generally speaking, let alone a professional aerospace paper written by an entertainment star, even a professional aerospace paper written by a university professor would not necessarily attract the attention of the Long March 5 project development team.

After all, apart from other aspects, the relevant technical experts are in this engineering development team.

As for those who are not in this team... don't they want to come?

You are not qualified to come!
Of course, this is somewhat absolute. After all, other projects are also being carried out simultaneously, and there are also talented people in those teams.

It’s just that they either don’t match the technology of the Long March 5, or have already participated in technical discussions through other channels.

Suddenly, a student of a university teacher who has nothing to do with the Long March 5 and is also an entertainment star appeared. It would be strange if the team took the aerospace professional paper he wrote seriously.

But it was transferred from one hand to another, and it was from Academician Ye Jianfei, so it’s different.

You should know that Li, the chief engineer of the Long March 5 rocket, is not an academician, but just a "young and middle-aged expert with outstanding contributions."

Deputy Chief Engineer Wang Weilin is about the same age as Chief Engineer Li, both about 20 years younger than Academician Ye Jianfei. They are not of the same generation or level as Academician Ye.

There's nothing much to say, just study it carefully.

Chief Engineer Li is watching the overall construction work of the next Long March 5 rocket at the First Academy, while Deputy Chief Engineer Wang Weilin is paying attention to the Long March 5's power system.

Although Ye Jianfei is not the direct superior of the Long March 5, nor the chief designer of Chang'e 5, he is the chief consultant, so there is nothing wrong with him asking about the progress of the Chang'e 5 carrying rocket and the Long March 5.

Wang Weilin gave him a brief report.

"...In fact, the second-stage rocket problem that occurred during the maiden flight has been resolved. It was not primarily a problem with the YF-75D engine, but rather a malfunction in the second-stage rocket's propellant utilization system, which expelled excessive hydrogen. During the late stages of the YF-75D's operation, the thrust chamber was extremely oxygen-rich, and the helical tube bundles were extremely low in hydrogen. The second stage operated for 17 seconds longer, equivalent to shutting down 7 seconds earlier at normal thrust."

“This is easy to solve.”

"So please rest assured that the Long March 5 Yao 2 can be launched on schedule, and the Yao 3 Chang'e 5 mission will not be delayed."

Ye Jianfei waved his hand and said, "Don't make any promises yet. The development of the YF-75D engine for the second-stage rocket is not difficult. After all, it's hard to say how much of an upgrade it is compared to our country's previous hydrogen-oxygen engines. However, the technological leap for the first-stage rocket's YF-77 engine is quite large. The most important thing for you now is to ensure that it is problem-free."

Wang Weilin was slightly stunned when he heard this. The YF-77 was indeed the first large-thrust liquid hydrogen and liquid oxygen engine developed in China. The thrust increased several times at once, directly increasing from a few tons to dozens of tons.

Although it still cannot catch up with the world's most advanced hydrogen-oxygen engine, it is already a great progress for China, and it has also laid the foundation for the development of the 220-ton thrust hydrogen-oxygen engine to be used in the second stage of the Long March in the future.

The most important thing is that there was no problem with the YF-77 engine during the Long March 's maiden flight!
Wang Weilin participated in the research and development of YF-77, and he is very familiar with this engine. It not only greatly improved the thrust of the domestic hydrogen-oxygen engine, but also got rid of the previous bulky design and optimized the lightweight design, which reduced the engine's own weight a lot.

Plus, it's being installed on the Long March 5, the most complex and largest rocket ever built in China, and it's had no issues on its maiden flight.

"That's the biggest problem!"

After reading the paper, the other members of the team all looked very serious.

They gathered around and said, "Maybe we haven't thought it through."

"Yes, we have always wanted to catch up with the world's top level, and this time we may have been a little too aggressive."

"The Long March 77 is the largest rocket ever built in my country, and the YF- is also the largest hydrogen-oxygen engine ever built in my country. Although we have tried our best to consider the complex operating conditions they will face, because we have never built such a large rocket with such a large span, we may not have considered more complex operating conditions..."

Wang Weilin didn't expect his colleagues to react so strongly after reading a paper, which made him realize the seriousness of the problem.

So he didn't say anything else and just read the paper written by Lu Yun.

When he finished reading it, his colleagues had already discussed the core issues and compared them with what he had thought of after reading the paper. Everyone nodded solemnly.

"There's a chance the turbo pump will malfunction!"

Everyone present was knowledgeable. Although the paper described many problems encountered by the Americans when developing hydrogen-oxygen engines, including problems with the turbo pump, they quickly thought of themselves.

Typically, a rocket engine requires a large turbopump to pressurize fuel into the combustion chamber, and its weight often accounts for more than half of the rocket engine. While meeting the overall rocket plan, designers will optimize the turbopump design—trying to make the turbopump as light and small as possible.

This is exactly where the problem lies.

"In pursuit of performance, we over-engineered the design, which actually reduced reliability."

"Especially when you don't have enough technical skills, doing this can cause serious problems!"

"Verification is easy. Just test it! Test it for a longer time and in more severe conditions!"

Many things in China are based on "stability", and this is especially true for aerospace engineering. After all, the development of domestic aerospace has cost many lives, and behind every regulation is a bloody lesson.

The situation where one insists on launching the product despite being questioned and refusing to believe that there is any problem with one's own design will not happen.

Now that you have thought of the problem, you cannot take it with you to heaven.

The test run is not difficult. The manufacturing speed of the YF-77 engine is not slow. There are already several engines in the test warehouse. They can be installed on the test bench for test runs.

It was just beyond everyone's expectations. At the beginning, they wanted to do a routine test drive first, and then a more aggressive test drive later. As a result, problems appeared as soon as the test drive began.

After the engine is started, the turbopump can reach the operating speed within one second, under high temperature and high speed, and then the local structure of the turbopump will break quickly and the engine will stall.

In the words of an expert from the turbo pump design department, "From crack to disconnection happens in the blink of an eye."

Everyone at the scene was dumbfounded.

But they didn't have time to stand there and watch, they quickly reacted, removed the engine with a damaged turbo pump, replaced it with another engine and continued testing.

As a result, three of the turbo pumps were damaged after testing five engines in a row, two of which were damaged during ordinary test runs, and one was damaged during a violent test run!

There is really a problem with the YF-77!
The fact that there were no problems during the maiden flight was pure luck. If the luck had been a little worse, the rocket and the satellite could have been dropped into the sea together!

"Sure enough, we were too optimistic. There are problems with the turbo pump design and the manufacturing process. We are struggling to master the one-piece molding technology that allows for extreme weight reduction."

"The next Long March 5 launch is only five months away, and it's probably too late for us to improve the design and manufacturing process of the turbopump now."

This is indeed a problem.

However, the technical experts present quickly pointed out that the YF-77 had a conservative design in the early days, using a split-structure turbopump. While its advantages were reliability, its disadvantages were that it was bulky and not as light as a one-piece structure, and its performance wasn't as good.

Someone else thought: "Yes, we have this design. We can use it on the few rockets that are about to be launched. The Long March 5 has a lot of design redundancy, which is enough to handle those missions. Then we can use a year to design a new high-tech turbopump..."

Everyone thought this plan was feasible and would not delay the launch mission.

The research and development team includes not only elderly and middle-aged experts, but also young elites in their twenties.

There are even people who graduated from Jinling University of Aeronautics and Astronautics, who have watched "Longing" and know that Lu Yun wrote a paper in it.

After all, Lu Yun was originally from the aerospace field, so they were all one of us.

Now the content of the paper is correct.

So one of the young people suggested, "Should we invite Lu Yun, the celebrity who wrote the paper, to come over?"

Everyone stared.

"Well, it's okay not to invite him. After all, we have a confidentiality policy..."

(End of this chapter)