Technology invades the modern world

Chapter 255 What?! Light Speed!
CCTV's studio was specially decorated with aerospace and mathematics themes.

Whether it was the rocket model or the mathematical formulas on the blackboard, everything showed how much importance was attached to Lin Ran.

When Lin Ran heard that he hoped to go up there and see it before he died, he sat quietly in the white chair opposite Xiao Sa, smiling with unwavering determination in his eyes:
“Teacher Sa, you are only twenty years older than me. I believe you will live to see that day come.”

Xiao Sa's attention wasn't on the age, but rather on the powerful confidence emanating from the interviewee in front of him.

Even though the studio was cramped, a small box in the steel jungle of Yanjing, the firmness in Lin Ran's tone seemed to instantly elevate his perspective, allowing him to overlook the entire solar system.

He seemed to see a thin line appearing between Mars and Earth, a connection that was not only unified in astronomical concepts but was also about to emerge at the level of real society.

Xiao Sa laughed too: "Professor, I believe you."

Lin Ran was somewhat surprised by the other party's support, because he knew before he came that CCTV interview programs often featured hosts who expressed too much of their own opinions.

“Okay, I look forward to interviewing Professor Lin on Mars when that day comes.”

CCTV's interviews are not broadcast live; they require post-production editing to ensure that the content released is acceptable.

With the popularization of mobile internet, the influence of CCTV's interviews is also rapidly declining.

In terms of reach alone, it's not even as effective as some interviews by self-media bloggers.

However, since the interviewee was Lin Ran, not many people watched the entire video, but the edited highlights were widely circulated.

New materials have been provided to everyone in WeChat and QQ groups within the Jiaotong University campus.

While the online world was abuzz with discussion, Lin Ran was already in Chang'an.

"Professor Lin, I've long admired your name. I've seen the exterior of Combustion-1, and my intuition tells me that it fully embodies your personal design philosophy," said Jia Yong, the dean of the Sixth Academy, welcoming him.

Lin Ran said, "It's actually just a small test of the capabilities of multi-engine parallel rockets."

It's a practice piece.

Recreating the Saturn V is our biggest task this year.

Upon hearing this, Jia Yong's expression immediately turned serious: "Professor Lin, I know your abilities are beyond question."

But spaceflight is no small matter; it has its own objective laws.

Especially since you're going to send people into space, you can't ignore the rules of the real world in pursuit of speed.

We discussed this in a previous remote video conference, so you should be well aware of the technical challenges of replicating the Saturn V in the modern era, right?

Lin Ran nodded and said, "Of course I know, you mentioned it back then."

In the 1960s, NASA engineers used innovative designs to ensure stable mixing of fuel and oxidizer in order to solve the problem of unstable combustion in the F-1 engine.

They conducted over 2000 experiments before finally finding an effective solution to the problem.

Even if we know every parameter and design drawing of the declassified technical documents, it's still too late.

Ultimately, we still need to rely on experiments to understand their design philosophy.

(F-1 rocket engine)
To rise to the position of director of the Sixth Academy, Jia Yong was undoubtedly a technocrat with a deep understanding of technology.

Jia Yong nodded: "Because whether it's the F-1 or the J-2, the most important thing is to replicate them. In the end, we still need to rely on a lot of testing to understand NASA's original thinking."

The person I arrange for you will also follow this logic.

We will provide you with sufficient manpower, but considering that this work mainly involves replication and testing, the staff will be more inclined to follow your orders.

Expecting them to be highly innovative or offer highly effective suggestions is probably unrealistic.

Lin Ran understood. To put it bluntly, the employees the other party provided wouldn't be of very high quality; they were likely just a bunch of people who hadn't been assigned any important tasks internally and were being dumped on him.

Anyway, you have to test it. By constantly producing prototypes and then testing them, you can ensure that what you produce is close to the F-1 of the 60s in terms of parameters and performance.

In Jia Yong's view, what Lin Ran needs to do is a job that requires thorough testing, relying on the amount of testing to continuously approach the final goal.

However, Jia Yong's arrangement was exactly what Lin Ran wanted, as what he needed were worker bees.

In the conference room, Lin Ran stood in front of the screen, on which a 3D model of the F-1 engine's injector plate was projected.

The team of engineers selected from the Sixth Academy sat around a long table, their notebooks filled with dense notes.

The team leader, Deputy Chief Engineer Zhang Xiaoqiang, sat in the main seat, his gaze focused, ready to listen to Lin Ran's guidance.

The name Zhang Xiaoqiang reminded Lin Ran of Zhang Xiaoping; the same position, a similar name.

Zhang Xiaoping was the deputy chief engineer at the Second Academy of Aerospace Science and Technology, responsible for the research and development of cryogenic engines. He earned an annual salary of 12 yuan while at the Second Academy. Later, he was poached by LandSpace, who said he had a high salary, but it is unclear exactly how high.

After Zhang Xiaoping was poached, the Second Academy issued an open letter: "Zhang Xiaoping's departure has had a great impact on the feasibility study and development of these four types of engines" and "will even affect the feasibility study and planning of my country's major strategic plan for manned lunar landing to some extent."

These are the exact words; it's hard to imagine that an annual salary of 12 could be so important.

Lin Ran was unsure of Zhang Xiaoqiang's skill level.

However, you'll know how good they are once you talk to them.

Lin Ran pointed to the screen: "Let's start with the F-1 engine."

The injector plate is the core component, containing 1428 oxidizer nozzles and 1404 fuel nozzles, for a total of 2832 nozzles.

Each nozzle is approximately 1 millimeter in diameter, requiring precise drilling to ensure a uniform mixture of fuel and oxidizer.

Zhang Xiaoqiang replied, "We have this data."

In the 60s, they used precision drilling machines, but each nozzle still needed to be inspected and adjusted manually.

Lin Ran nodded and said, "Yes, they control the tolerance within 0.025 millimeters. Any deviation could lead to uneven combustion."

We now have more advanced equipment, using similar high-precision drilling machines and equipped with large imaging systems for hole-by-hole inspection.

Zhang Xiaoqiang instructed his engineers to record: "Understood, we have CNC drilling machines and will set them according to the original tolerances."

Lin Ran continued, "Very good. The material of the sprayer plate is 304 stainless steel, and the nozzle is lined with copper to prevent high-temperature corrosion."

The copper lining requires electrical discharge machining to ensure a smooth inner wall.

Then comes the most crucial issue: combustion instability.

Lin Ran switched to the cross-sectional view of the injector plate:

"In the original design, during early F-1 tests, pressure oscillations of 4 to 24 kilohertz were observed in the combustion chamber, and in one test in 1961, the engine even burned out."

NASA solved the problem by welding 13 copper baffles, using AMS 4777 nickel-based solder in a vacuum at 1093°C.

The final solution was to weld copper baffles onto the injector plate to form 13 compartments, including 2 annular baffles and 12 radial baffles.

These baffles alter the acoustic characteristics of the combustion chamber, suppressing lateral and tangential oscillations.

Zhang Xiaoqiang grasped the key point of the question: "How are the baffles manufactured and welded?"

Lin Ran replied, "The baffle is also made of copper and is fixed to the injector plate by vacuum brazing."

The baffle plate is 2 cm thick and requires electrical discharge machining to ensure a smooth surface. Before welding, the contact surfaces must be free of oxides, and the weld integrity must be inspected using X-rays.

Zhang Xiaoqiang then asked, "What about the combustion chamber? We know that the F-1's regenerative cooling system is very complex."

Lin Ran switched to the combustion chamber model: "Yes, the combustion chamber is composed of hundreds of Inconel-X750 alloy tubes, arranged longitudinally and vacuum brazed into one piece."

RP-1 fuel flows through these pipes, cools the combustion chamber walls, and is then injected into the injectors.

The pipe wall thickness is approximately 0.5 mm, and precise temperature control is required during brazing to prevent overheating of the material.

Inconel-X750 alloy is a nickel-chromium alloy that can be precipitation hardened by adding aluminum and titanium, and has high creep fracture strength at high temperatures of approximately 700 degrees Celsius.

This alloy is often used in fields such as nuclear reactors, rocket engines, and aircraft structures.

Upon hearing this, Zhang Xiaoping frowned and said, "We have experience in brazing, but Inconel-X750 is hard to find now."

Can other alloys be used as substitutes?

It's not that China can't manufacture Inconel-X750, but rather that the limited demand for this alloy leads to limited production. Replicating it means there's a huge demand, making it difficult to provide enough supply in a short period of time.

Lin Ran shook his head and said, "In order to replicate it, we must use Inconel-X750. Its high temperature resistance and corrosion resistance have been verified."

If we can't find it, we'll consider Inconel 718, but additional testing is required to ensure a match in coefficients of thermal expansion.

(Inconel series)
Lin Ran continued, "Next is the turbopump. The F-1's turbopump needs to deliver approximately 2.7 tons of RP-1 and 4.7 tons of liquid oxygen per second."

The turbine is driven by a gas generator and is made of high-strength stainless steel, while the impeller is made of aluminum alloy to reduce weight.

The impeller requires extremely high machining precision.

The dynamic balance of the impeller needs to be controlled within 0.1 g/mm, otherwise high-speed rotation will cause vibration.

Back in the 1960s, we—no, NASA—used manual balancing machines to calibrate each one individually. We can use modern equipment, but the process must remain the same.

Lin Ran's situation isn't surprising to us.

Zhang Xiaoqiang nodded and said, "Okay, Professor Lin, let's move on to the next topic, the J-2 engine."

What's special about its injector design?

Lin Ran switched to the J-2 model: "The J-2 uses a coaxial injector, with liquid hydrogen and liquid oxygen injected through a concentric tube, with liquid hydrogen on the outside and liquid oxygen on the inside."

This design facilitates efficient mixing, achieving a specific impulse of 428 seconds. Early designs used copper injectors, but uneven heating and melting resulted in green exhaust gases.

They later switched to a coaxial design based on RL10, which solved the problem.

Zhang Xiaoqiang asked, "What about the materials and manufacturing process of the ejector?"

Lin Ran: "The main body of the injector is made of stainless steel, and the nozzle is made of copper alloy."

The number of nozzles is fewer than that of the F-1, but the concentricity requirement for each nozzle is extremely high, requiring precision lathe machining and individual inspection.

Zhang Xiaoqiang: "Cryogenic processing of liquid hydrogen is a challenge. How can turbopumps cope with this?"

Lin Ran: "The J-2's fuel turbopump operates at -253°C, so the impeller and housing must be made of Inconel or 316 stainless steel."

The seal employs a labyrinth seal to minimize leakage. The bearing lubrication system is cooled with liquid hydrogen to prevent freezing.

Zhang Xiaoqiang asked, "How are the F-1 and J-2 tested?"

Lin Ran: "After each assembly, the F-1 undergoes a static ignition test, which lasts for about 150 seconds, equivalent to the flight time."

The monitored parameters include thrust, combustion chamber pressure, temperature, and vibration.

Because the J-2 uses an upper-stage engine, it requires high-altitude simulation testing in a vacuum chamber to verify its performance under low-pressure conditions.

Lin Ran's testing method was quite standard. After listening, Zhang Xiaoqiang simply wanted to confirm that the other party truly understood it. He then asked, "What about quality control? Are there any special inspection methods?"

Lin Ran: "Each component must undergo non-destructive testing."

The injector plate is inspected for welds using X-rays, the combustion chamber is tested for cracks using ultrasound, and the turbopump is inspected for surface defects using dye penetration testing.

After each engine is assembled, a full system pressure test is conducted.

Wang Qiang: "What should we do if there is a shortage of materials, such as Inconel-X750?"

Lin Ran: "Try to find the closest alternative, such as Inconel 718, but thermodynamic and mechanical performance tests must be conducted to ensure consistency with the original design."

Any changes require additional verification.

But ultimately we must avoid this situation from occurring.

If it's a funding issue, I can cover the expenses.

In short, remember that replication is not just about copying blueprints; it's also about understanding the engineering logic behind each design element. Let's begin.

Inside the manufacturing workshop, precision drilling machines are neatly arranged, and the smell of cutting fluid permeates the air.

Lin Ran stood beside a drilling machine, instructing the engineer.

The semi-finished injector plate is fixed on the workbench, its 304 stainless steel surface gleaming with metallic luster.

Lin Ran picked up a depth gauge: "The depth of this nozzle must be accurate to 0.1 millimeters, and the angle deviation cannot exceed 0.01 degrees. Look, there are tiny burrs here, which need to be sanded with fine sandpaper."

“Yes, Professor, I will be very careful.”

Lin Ran used an optical microscope to examine a nozzle; the screen showed that the edges were smooth and flawless.

Lin Ran said with satisfaction, "This nozzle is up to standard. All 2832 nozzles must meet this standard."

"So many nozzles, each one needs to be perfect, the workload is enormous," Zhang Xiaoqiang thought to himself.

The engineer asked, "Professor, how is the copper lining processed?"

"The copper lining is machined by electrical discharge machining, with an inner wall roughness of Ra 0.4 micrometers. After machining, it is cleaned with ultrasonic waves to remove residual particles," Lin Ran said without hesitation.

Lin Ran inspected each of the rows of nozzles and found that the angle of one of the nozzles was 0.02 degrees off.

Lin Ran said seriously, "This nozzle is substandard and needs to be re-drilled."

The combustion chamber pressure reaches as high as 70 bar; any deviation could trigger oscillations.

A bar is a unit of pressure; 1 bar = 100 kilopascals.

The engineer nodded and readjusted the drilling machine parameters.

Lin Ran reiterated: "Precision is the top priority, and there can be no compromise."

After the copper baffle was processed, the team brazed it in a vacuum furnace.

Lin Ran supervised the brazing process to ensure the temperature remained stable at 1093℃.

Lin Ran: "Immediately after brazing, X-ray inspection should be performed, as any micro-cracks could lead to failure."

"Understood, we will check each piece individually."

Inside the vacuum furnace control room, engineers monitor the temperature curves.

Lin Ran stood in front of the display screen, where 178 Inconel-X750 tubes were neatly arranged inside the furnace, with brazing filler metal evenly applied.

Lin Ran: "The heating rate is 5°C per minute. After reaching 1093°C, it is maintained for 30 minutes and then slowly cooled. Rapid temperature changes can cause the tube to deform."

"The program has been set up and will be strictly controlled."

The vacuum pump hummed, and the pressure inside the furnace dropped to 10^-5 Torr.

Torr is also a unit of pressure, 1 tor = 133.322 Pa.

Lin Ran thought to himself, "Bragging is the bottleneck in F-1 manufacturing; any mistake could ruin weeks of hard work."

Thirty minutes later, cooling began. The furnace door was opened, and the combustion chamber tube walls were smooth with no obvious defects.

"Initial inspection shows that the pipes are evenly arranged and without deformation."

Lin Ran: "Okay, conduct ultrasonic testing immediately to confirm the quality of the weld."

The test results showed that the weld was intact with only one tiny pore. Lin Ran suggested that the weld be re-welded locally to ensure perfection.

In the balancing lab, a 1960s-style manual balancing machine was put into use.

Lin Ran personally demonstrated the impeller calibration.

Lin Ran: "This balancing machine is a replica of the original design. We want to reproduce NASA's calibration process."

He installed the aluminum alloy impeller on the balancing machine, started the rotation, and the screen showed an imbalance of 0.3 grams per millimeter.

Lin Ran: "We need to drill small holes in the impeller for alignment. Based on the phase, the drilling location is here."

He marked the location, and engineers from China Aerospace were responsible for attempting to operate it.

"Professor, how do we determine the borehole depth?"

Lin Ran: "Based on the calculation of the unbalance, a small hole with a depth of 0.1 mm is usually sufficient."

Test again after drilling is complete.

After three adjustments, the imbalance was reduced to 0.08 grams per millimeter.

Lin Ran: "Pass! Each impeller must be calibrated like this."

Zhang Xiaoqiang, standing to the side, thought to himself, "Isn't the professor a little too proficient?"
"It's amazing how precise such old equipment can be used."

From the moment Zhang Xiaoqiang received the mission, he knew that Lin Ran was an expert in the Apollo moon landing.

After a month of collaboration, Lin Ran's expertise and what he thought he was an expert in were completely different things.

Zhang Xiaoqiang knew that Lin Ran was studying in America and that she was a huge fan of the Apollo moon landing.

His perceived expertise amounted to, at best, finding information that was unavailable to outsiders and knowing some technical secrets unknown to the outside world.

That's all.

It simply means being able to avoid some detours during the research and development process.

However, the necessary tests, the necessary attempts, and the efforts of engineers to find ways to achieve the goal are all essential steps.

To call it a replica is an understatement; a more accurate description would be a replica-style development.

You've only explored a portion of the map at most, and then you explore further based on that portion.

Research and development itself is like an exploration process, which requires constant trial and error. Replicating, on the other hand, involves fewer trial and error steps.

Even if America wanted to replicate the Apollo moon landing or recreate the F-1 engine, it would still have to conduct over two thousand combustion instability tests.

It will take at least seven or eight years.

In addition to other steps, repeated testing and verification were conducted.

Therefore, it's one thing for America not to restart the Apollo moon landing so that Commissioner Smith and his team can make a fortune, but it's another thing that the replica itself has no cost-effectiveness whatsoever.

This was Zhang Xiaoqiang's understanding before collaborating with Lin Ran.

But after the collaboration, his understanding was completely overturned.

Lin Ran's performance was less about being proficient and more about having a thorough understanding of every detail.

It's usually written in just one sentence in a report, but the underlying principles may have taken thousands of hours to figure out.

Lin Ran's so-called expertise, down to the specific steps involved, was explained to the engineers at the Sixth Academy on the spot.

This made Zhang Xiaoqiang question his life. If the other person wasn't only 24 years old, he would have suspected that the other person had been involved in the research and development and manufacturing of the F-1 engine.

J-2 jet manufacturing takes place in a separate workshop.

Lin Ran inspects the machining of the coaxial nozzles; the main body of the 316 stainless steel injector is fixed on the lathe.

Lin Ran emphasized: "The concentricity deviation must not exceed 0.01 millimeters, and it must be checked hole by hole with a micrometer."

"Yes, Professor, I have checked all 10 nozzles, and they are all up to standard."

Lin Ran picked up a copper alloy nozzle and examined its surface.

Lin Ran: "The nozzle roughness Ra is 0.2 micrometers, which is very good."

Keep it up.

The J-2 combustion chamber was brazed in another vacuum furnace, with 540 316 stainless steel tubes arranged neatly.

Lin Ran: "Bragging temperature 1050-1070℃, heating rate 3℃ per minute, hold for 25 minutes."

"The pressure inside the furnace has reached 10^-6 Torr, and the program is running normally."

After brazing, the combustion chamber tube wall was smooth, and ultrasonic testing confirmed that there were no defects.

Lin Ran: "Perfect! This batch of combustion chambers can now be assembled."

The liquid hydrogen turbopump is manufactured in a cryogenic laboratory.

Lin Ran guided the team to test the labyrinth seal.

Lin Ran: "Run the pump body in liquid nitrogen at -253℃ for 10 minutes to check the sealing."

"No leakage, and the bearing temperature is stable."

Lin Ran: "Very good. The bearings are cooled with liquid hydrogen to ensure they don't freeze."

In the assembly hall, components of the F-1 and J-2 engines were neatly arranged. Lin Ran supervised the assembly, providing guidance on bolt torque and gasket installation.

Lin Ran: "The F-1 injector plate is connected to the combustion chamber with a bolt torque of 50 Nm and the gasket is undamaged."

"Yes, Professor, I will check them one by one."

During the assembly of J-2, Lin Ran discovered a deviation in a liquid hydrogen pipeline joint.

Lin Ran: "This joint is 0.05 mm off and needs to be realigned, otherwise it may leak."

The team quickly adjusted and completed the assembly. All components underwent X-ray, ultrasonic, and dye penetration testing to ensure they were defect-free.

Inside the test range, the F-1 engine is mounted on a test stand, and real-time data is displayed on the control room screen.

Lin Ran: "150-second static ignition, monitoring thrust, specific impulse, and pressure."

Zhang Xiaoqiang personally served as the commander of this test: "10 seconds countdown! 3, 2, 1, ignition!"

Flames erupted, generating a thrust of 6770 kN, equivalent to 152.2 million pounds, with a specific impulse of 263 seconds and a pressure of 70 bar.

The engineer in charge of monitoring the data exclaimed excitedly, "The data is stable, with no fluctuations!"

Lin Ran: "Compared with Apollo 11 data, the performance is completely identical."

Subsequently, the testing of the J-2 engine also proceeded smoothly.

The liquid hydrogen system is perfectly sealed, and the combustion efficiency meets expectations.

The J-2 was tested in a vacuum chamber, with a thrust of 1033 kN and a specific impulse of 421 seconds. All three ignitions were normal.

"The weight is 1790 kg, which is only 0.1% different from the original 1788 kg."

Zhang Xiaoqiang added: "We compared the data of the Saturn V and found that the F-1 and J-2 are a perfect match in terms of performance."

It also passed non-destructive testing and pressure pulse testing.

After leaving the production workshop and returning to the conference room, the engineering team cheered, using water glasses instead of wine glasses to celebrate.

"bang bang bang"

"Please come in," Jia Yong said.

"Dean, I've come to report to you." Zhang Xiaoqiang pushed open the door and entered.

(End of this chapter)