Super Copy of Great Power Technology

"Five minutes of preparation, collecting real-time weather information, and making final flight corrections. The current temperature is 24 degrees Celsius, the humidity is 42%, the air pressure is 0.10233MPa, the north wind is level 3, and there are no obvious clouds in the high altitude, which meets the conditions for rocket flight testing."

"One minute to prepare, the gas supply pipeline is disconnected, the power transmission cable is disconnected, the communication cable is disconnected, and the rocket's wireless information transmission link is turned on."

As the command was given, the various pipelines originally fixed on the first rocket were automatically detached, pulled out by pre-set automatic facilities, and sent back to the underground shaft. The manhole covers that were originally open were also covered again to prevent subsequent flames.

“10、9、8、7、6、5、4、3、2、1、点火！”

The countdown ended, the ignition command was issued, and Cao Yifei suddenly pressed the ignition button. The next moment, a small yellow flame spurted out from the tail of the Suzaku rocket, and quickly spread to all five Tianque engines. The blazing flames burst out, scorching the concrete floor, and making a loud rumbling sound. This spectacular scene lasted for more than a second. The Suzaku rocket's first-stage module, which was much lighter than the complete rocket, flew up under the huge thrust.

"Takeoff time: 20:9.5:: a.m. Current altitude: meters, remaining fuel: %, stable flight."

"Flight altitude 90 meters, remaining fuel 9.5%, positioning deviation 0.5 meters, automatic correction in progress."

"Flight altitude 170 meters, remaining fuel 9.4%, positioning deviation 0.1 meter."

"Flight altitude 300 meters, remaining fuel 9.3%, positioning deviation 0.2 meter."

"Flight altitude 400 meters, remaining fuel 9.3%, reaching designated altitude, hovering procedure initiated. Engines 1, 2, 3, and 4 shut down, leaving only engine 5 running, thrust self-adjustment procedure activated, current hovering altitude 413 meters."

As the commander continued to broadcast, the first-stage rocket flew higher and higher, soon surpassing the tower crane erected on the construction site, and continued to rise until it was about the same height as a few white clouds in the sky, then it stopped rising and hovered there. At the rocket recovery site, there were flames and loud explosions, which naturally attracted the attention of a large number of construction workers nearby. Some of those who were unaware thought it was thunder on a sunny day and were shocked.

"Emma, ​​what's that noise? Is that a helicopter coming?"

"What the hell, that's a helicopter! It's our contractor, Party A, who's testing a rocket. Look over there, the rocket is flying!"

"So this thing is a rocket. I thought it was a chimney erected in a factory."

"Wow, this rocket is really awesome, it spews fire and makes a loud roar. Look, there are words on the rocket body, Ruida Aerospace, it is indeed something made by the client of our project."

"Hey, look, the rocket has stopped. How high did it fly? About 500 meters? Why did it stop?"

"I can tell you didn't observe carefully. Didn't you see that there are four supporting legs at the bottom of the rocket? I guess this rocket has a recovery function. Ruida Aerospace is conducting a rocket recovery test."

"I read in the news that only one private aerospace company in the United States has mastered the mature rocket recovery technology in the world. We in China probably don't have it. If Ruida Aerospace can really complete the rocket recovery test, it will be the first in China."

"Isn't the function of this carrier rocket to send satellites into space? As long as the delivery mission is completed and the rocket debris doesn't hit anyone, what difference does it make whether it is recovered or not?"

"You only know one side of the story. This rocket can be reused many times after it is recovered, which can greatly reduce the cost of satellite launches. It can be said that the company that first masters rocket recovery technology will have an absolute competitive advantage in the commercial aerospace field. Just a low price can crush a number of aerospace companies."

"So, if this is the case, then this Ruida Aerospace has already conducted a rocket recovery test, isn't their technology very advanced?"

"It hasn't been recovered yet. Even if it was successful, it was just a low-altitude recovery test. It's not the same as the recovery after the rocket completed the satellite launch mission and flew back from an ultra-high altitude of about 70 kilometers. The difficulty of the latter is at least ten times that of the former."

Qiao Ruida, who was in the temporary control center, of course could not hear the discussion of the surrounding construction workers. All his attention was focused on the several screens in front of him. They showed the hovering image of the first-stage rocket, as well as various environmental parameters and flight parameters.

"Have we loaded too much methane and liquid oxygen on this rocket? It's been hovering for two minutes, and there's still more than 7% left. How long will it take to hover if we want to use it all up?" Cao Yifei frowned and said as he stared at the slowly decreasing fuel remaining.

"In order to cope with emergencies, a 5% margin is reserved when loading the fuel. The weather is particularly good today and there is little wind, so the extra fuel will not be used." Candice stated the principle of pre-loading fuel. In fact, this is not only the case for test rockets, but also for actual launch vehicles. Some fuel will be reserved to deal with various accidents.

"Don't worry, the recovery system of our Suzaku rocket is designed with a large safety margin. Even with this 7% of fuel, it won't be dangerous. But in order to test the hovering performance of the rocket and the power regulation ability of the engine, let's let it fly for a while longer." Qiao Ruida's words gave everyone a reassurance. The design of this Suzaku rocket was brought out by Qiao Ruida, and he was the only one who knew the performance of the rocket best. Since he said it was okay, it really was okay.

"Rui Da, I see that the altitude of this rocket is constantly fluctuating, with a difference of more than 30 meters up and down. It's not as stable as the quadcopter I control. Is it because of your flight control program?" Du Qingqing pointed at the altitude parameters that kept jumping up and down on the screen and raised her doubts.

"This is not a problem of flight control technology. Instead, as the hovering time gets longer and longer, the fuel on board is constantly consumed, the weight of the entire rocket is constantly decreasing, and the center of gravity is constantly moving. This requires the rocket to constantly adjust the output size and direction to maintain spatial positioning. Didn't you see that after entering the hovering state, the four surrounding Tianque engines were shut down, leaving only the middle engine working. The power point is very concentrated, and it is already quite difficult to maintain the stability of the entire rocket and the positioning offset within 0.5 meters. It is normal to have some ups and downs." Qiao Ruida operated the mouse to focus on the tail engine part of the rocket, and then pointed to the only working engine and explained to his girlfriend. "So that's how it is. It seems that I thought things were simple." Du Qingqing stuck out her tongue, retracted her gaze, and concentrated on controlling the drone to take pictures.

After the first-stage rocket hovered at an altitude of 400 meters for eight minutes, the remaining fuel dropped to about 3%. Qiao Ruida finally gave the order, "Okay, we can start the rocket recovery operation."

"Rocket recovery program started, automatically searching for the ground landing point, locked successfully, rocket translation in progress, translation completed, landing point locked, descent process started."

There are three recovery points on the recovery platform, each marked with a cross in a different color. The landing point of the first-stage rocket is exactly the center of the red cross in the middle. The horizontal distance from the rocket hovering point to the landing point is about fifty meters. After the recovery command was issued, the rocket control program automatically fine-tuned the engine's injection angle and injection volume, and controlled the rocket body to move horizontally in the direction of the landing point. The entire translation process was slow and stable, and the height control was also very good. It was only a few meters higher than when it was hovering just now. After the translation was in place, the orange flame emitted by the engine further shrank, and the power also decreased. The rocket slowly and firmly fell to the ground.

"Look, the rocket flying in the sky is moving. It's so big, but it's flying so steadily. It must be something."

"It has been hovering for several minutes. I'm afraid it needs to be recovered."

"It should be. Didn't you see that the rocket has started to drop in altitude? At this rate, it will soon fall back to the ground."

"Based on the current situation, the rocket launched by Ruida Aerospace has a high chance of success. Whether it will succeed depends on whether it can maintain stability when landing."

"The rocket has fallen. From our direction, the rocket body seems to be a little tilted. Hey, I didn't expect that the four inconspicuous supporting legs actually supported the rocket body and did not fall over. This can be considered a successful recovery."

"Of course it succeeded. Today we have witnessed a new chapter in Chinese aerospace history. The rocket was successfully recovered. It is worth congratulating. Everyone, please applaud with me."

"Wow, wow, wow, wow!" The construction workers who witnessed the entire process of the Suzaku rocket's first stage from launch to hovering to successful recovery were also very excited. I don't know who started the applause first, and then it quickly spread to the surrounding applause.

At this time, the temporary control center was in complete silence. Qiao Ruida, Cao Yifei and others were all sweating. When the first-stage rocket was about to land, the rocket body did tilt, and the tilt angle reached 8 degrees. The rocket was able to land successfully on the ground without tipping over, entirely relying on the four hydraulic legs, which had a strong support capacity.

Qiao Ruida operated the computer and played the surveillance footage of the rocket landing four or five times, even in slow motion, until he paused at a certain moment. He pointed at the engine on the screen and asked loudly: "Can anyone tell me why the rocket shut down before it landed on the ground?"

Everyone shook their heads, somewhat confused. According to the standard process for rocket recovery, when the rocket descends and approaches a hundred meters from the ground, the rocket should re-ignite, adjust the flight attitude and landing point, and decelerate the rocket. During the entire landing process, the engine will only gradually reduce the thrust and will not shut down. The engine will not shut down until the rocket is successfully recovered and completely falls back to the ground. This time, the first-stage rocket conducted a low-altitude takeoff recovery test. During the entire test process, the No. 5 engine remained on, and even the possibility of a secondary ignition failure was avoided. However, the monitoring image showed that when the rocket was about five meters from the ground, the No. 5 engine actually shut down, which caused the rocket body to tilt. This is obviously not a normal recovery process. There must be a problem somewhere.

"Mr. Qiao, could it be that the rocket fuel burned out prematurely and the engine had no fuel available, causing it to stall prematurely?" Wu Ziqiang put forward his speculation.

Candice shook her head decisively and said, "Look at the rocket fuel decline curve on this screen. When it finally landed, there was still more than 2% of fuel left, both for methane and liquid oxygen."

"Could it be that there was a problem with the ground detector, causing the control program to think that the rocket had landed on the ground and thus shut down the engine?" another engineer speculated.

"It shouldn't be possible. We have installed three ground detection devices at the tail of the rocket, including ultrasonic echo detection, optical detection, and three-dimensional signal positioning. It doesn't make sense for the three detectors to fail at the same time, right?"

"There is another possibility, that is, there is an error in the flight control program we wrote."

……

"It's not difficult to find out the cause of the accident. All we need to do is connect the data cable, retrieve the rocket's flight log, and check it carefully, and we'll know."

"That makes sense. Now that the rocket has been successfully recovered, the flight log is stored in the memory chip. We can just pull it out and take a look, and all the problems will be clear at a glance."

"What are you waiting for? Hurry up and act. It has been more than ten minutes since the rocket landed. The engine has cooled down almost completely. There is no danger for people to get close."

Everyone expressed their opinions and proposed more than a dozen possible reasons for the premature engine shutdown, arguing endlessly. Finally, with Candice's reminder, everyone realized that although there were some twists and turns during the rocket recovery process, it was finally recovered successfully. If you want to know what went wrong, you just need to connect the cable and call up the system log. Even if you still can't find the problem after reading the log, you can still disassemble the rocket and check each component one by one to find out the reason for the premature engine shutdown.

Cao Yifei and Candice took the lead, walked out of the temporary control center, and walked towards the first-stage rocket in the middle of the recovery platform, which was still emitting Sisi's heat. Behind them, followed a large group of engineers with heavy expressions. Qiao Ruida held his girlfriend's hand and walked at the end of the crowd. The expression on his face had returned to peace, because he had figured out the crux of the problem through the photo analysis function of the golden finger. The culprit for the premature engine shutdown was really in the flight control program. There was a small mistake in the logical statement that judged whether the rocket had landed on the ground. "all" was mistakenly written as "or", resulting in a misjudgment. (End of this chapter)