Chapter 255: What Lightspeed!
The CCTV studio was specially decorated with aerospace and mathematics themes.
Whether rocket models or mathematical formulas on the blackboard, all demonstrated the importance attached to Lin Ran.
When Lin Ran heard that he hoped to go up and see it in his lifetime, he sat quietly smiling on the white chair opposite Xiao Sa, with an extremely determined gaze:
“Teacher Sa, you’re only over twenty years older than me. I believe you’ll see that day arrive.”
Xiao Sa’s attention was not on age, but he profoundly sensed a powerful confidence from the interviewee in front of him.
Even though the studio was cramped, a small square box in the steel jungle of Yanjing, Lin Ran’s firm tone seemed to instantly elevate his perspective infinitely, overlooking the entire solar system.
He seemed to see a thin line appearing between Mars and Earth; not only did they have a unified connection in astronomical concepts, but in reality, a connection was about to emerge on the social level as well.
Xiao Sa also smiled: “Professor, I believe in you.”
Lin Ran was somewhat surprised that the other was giving such strong support, because before coming, he knew that CCTV interview programs always had hosts with excessive self-conscious expressions.
“Good, I’m looking forward to interviewing Professor Lin on Mars when that day comes.”
CCTV interviews are not live broadcasts and require post-editing to ensure the content aired is appropriate.
With the popularity of mobile internet, the influence of CCTV interviews is also rapidly declining.
Purely in terms of dissemination range, it’s even less than some self-media bloggers’ interviews.
But the interviewee this time was Lin Ran; few watched the entire video completely, but the edited highlights were widely disseminated.
In the WeChat groups and QQ groups within Jiaotong University campus, it provided everyone with new material again.
While cyberspace was abuzz, Lin Ran was already in Chang’an at this time.
“Professor Lin, I’ve long admired your name. I’ve seen the exterior of Burning No. 1; my intuition from the appearance is that it fully embodies your personal design concept inside.” Sixth Academy Dean Jia Yong welcomed him.
Lin Ran said: “It’s actually just a small test for a multi-engine parallel rocket.
It’s a practice piece.
Replicating Saturn V is our big task this year.”
After hearing this, Jia Yong’s expression immediately turned serious: “Professor Lin, I know your ability is beyond doubt.
But aerospace is not a trivial matter; it has its own objective rules.
Especially since you’re sending people into space, you must not pursue speed at the expense of neglecting the rules of the real world.
We discussed it in the remote video meeting before; you should be very clear about the technical difficulties in replicating Saturn V in modern times, right?”
Lin Ran nodded: “Of course I know; you mentioned it at the time.
NASA’s engineers in the 1960s solved the combustion instability problem of the F-1 engine by adopting an innovative design to ensure stable mixing of fuel and oxidizer.
It took them over 2000 experiments to effectively solve the problem.
Even with declassified technical data, no matter how clear we are on every parameter and every design drawing.
Ultimately, it still comes down to experiments to figure out their design concept.”
(F-1 rocket engine)
To be Sixth Academy Dean, Jia Yong was undoubtedly a technocrat, very knowledgeable about technology.
Jia Yong nodded: “Because whether F-1 or J-2, the key to replication is ultimately to understand NASA’s thinking back then through a large number of tests.
The people I arrange for you will follow this logic.
I’ll arrange sufficient manpower for you, but considering this work is mainly replication and testing, in terms of manpower, they will mostly follow your commands.
It’s unrealistic to expect them to have high innovation or propose very effective suggestions.”
Lin Ran understood; in plain terms, the provided employees wouldn’t be of high quality, likely just a group of people not assigned important internal tasks, dumped on him.
Anyway, you’re doing testing, continuously producing prototypes, then testing, to ensure what you produce approaches the 1960s F-1 in parameters and performance.
In Jia Yong’s view, what Lin Ran needed to do was a job requiring extensive testing, piling up tests to continuously approach the final goal.
However, Jia Yong’s arrangement suited Lin Ran’s intentions perfectly; what he needed were worker bees.
In the meeting room, Lin Ran stood in front of the curtain, with a 3D model of the F-1 engine injector plate projected on the screen.
The engineer team selected by Sixth Academy sat around the long table, with notebooks filled with dense notes.
The team leader, Deputy Chief Engineer Zhang Xiaoqiang, sat at the head, gaze focused, ready to listen to Lin Ran’s guidance.
The name Zhang Xiaoqiang reminded Lin Ran of Zhang Xiaoping, similar position, similar name.
Zhang Xiaoping was the deputy chief engineer in charge of cryogenic engine R&D at Second Academy of Spaceflight; at Second Academy, his annual salary was 120,000, later poached by LandSpace with a high salary, but the exact amount unknown.
After Zhang Xiaoping was poached, Second Academy issued an open letter: “Zhang Xiaoping’s personal resignation has had a tremendous impact on the proposal demonstration and development work of these four types of engines” “even to some extent affecting the demonstration and planning work of our country’s manned moon landing major strategic plan.”
These were the original words; hard to imagine a 120,000 annual salary could be so important.
Lin Ran didn’t know Zhang Xiaoqiang’s level.
But level or not, chatting would reveal it.
Lin Ran pointed to the screen: “Let’s start with the F-1 engine.
The injector plate is the core component, containing 1428 oxidizer orifices and 1404 fuel orifices, totaling 2832 orifices.
Each orifice is about 1 mm in diameter, requiring precise drilling to ensure uniform mixing of fuel and oxidizer.”
Zhang Xiaoqiang replied: “We have this data.
In the 1960s, they used precision drilling machines, but each orifice needed manual inspection and finishing.”
Lin Ran nodded: “Yes, they controlled tolerances to within 0.025 mm; any deviation could cause uneven combustion.
We now have more advanced equipment, using similar high-precision drilling machines equipped with large image gauges for per-orifice inspection.”
Zhang Xiaoqiang instructed the engineers to record: “Understood, we have CNC drilling machines and will set them to the original tolerances.”
Lin Ran continued: “Good. The injector plate material is 304 stainless steel, with copper liners in the orifices to prevent high-temperature erosion.
Copper liner processing requires electrical discharge machining to ensure smooth inner walls.
Then the most critical issue: combustion instability.”
Lin Ran switched to the injector plate cross-section diagram:
“In the original design, early F-1 tests showed 4 to 24 kHz pressure oscillations in the combustion chamber; one 1961 test even burned out the engine.
NASA solved it by welding 13 copper baffles, using AMS 4777 nickel-based brazing filler in vacuum brazing at 1093°C.
The final solution was welding copper baffles on the injector plate, forming 13 compartments, including 2 ring baffles and 12 radial baffles.
These baffles altered the combustion chamber’s acoustic properties, suppressing tangential and radial oscillations.”
Zhang Xiaoqiang grasped the key point: “How were the baffles manufactured and welded?”
Lin Ran replied: “The baffles are also copper, fixed to the injector plate by vacuum brazing.
Baffle thickness 2 cm, requiring electrical discharge machining for smooth surfaces. Before welding, contact surfaces must be oxide-free, with X-ray inspection for weld integrity.”
Zhang Xiaoqiang then asked: “What about the combustion chamber? We know the F-1 regenerative cooling system is very complex.”
Lin Ran switched to the combustion chamber model: “Yes, the combustion chamber consists of hundreds of Inconel-X750 alloy tubes, arranged longitudinally and vacuum brazed into one piece.
RP-1 fuel flows through these tubes, cooling the chamber walls before injection into the injector.
Tube wall thickness about 0.5 mm, requiring precise temperature control during brazing to avoid overheating the material.”
Inconel-X750 alloy is a nickel-chromium alloy that can be precipitation hardened by adding aluminum and titanium, with high creep rupture strength at around 700°C.
This alloy is commonly used in nuclear reactors, rocket engines, and airplane structures.
Zhang Xiaoping frowned upon hearing this: “We have experience with brazing processes, but Inconel-X750 is hard to find now.
Can we use other alloys as replacements?”
It’s not that China can’t produce Inconel-X750, but demand is limited leading to limited production; replication means high demand, making sufficient supply difficult in a short time.
Lin Ran shook his head: “For replication, we must use Inconel-X750; its high-temperature and corrosion resistance have been verified.
If unavailable, consider Inconel 718, but additional testing is needed to ensure matching thermal expansion coefficients.”
(Inconel alloy series)
Lin Ran continued: “Next is the turbopump. The F-1 turbopump needs to deliver about 2.7 tons of RP-1 and 4.7 tons of liquid oxygen per second.
The turbine is driven by a gas generator, material high-strength stainless steel, impeller in aluminum alloy to reduce weight.
The impeller machining precision is very high.
Because impeller dynamic balance must be controlled within 0.1 g-mm, otherwise high-speed rotation causes vibration.
In the 1960s, we—no, NASA used manual balancing machines for individual calibration; we can use modern equipment, but the process must be consistent.”
Lin Ran’s “we” wasn’t abrupt.
Zhang Xiaoqiang nodded: “Good, Professor Lin, let’s continue to the next topic, the J-2 engine.
What are the special features of its injector design?”
Lin Ran switched to the J-2 model: “J-2 uses coaxial injectors; liquid hydrogen and liquid oxygen are injected through concentric tubes, hydrogen outside, oxygen inside.
This design promotes efficient mixing, specific impulse reaching 428 seconds. Early designs used copper injectors, but uneven heating caused melting, leading to green exhaust.
Later they switched to a coaxial design based on RL10, solving the problem.”
Zhang Xiaoqiang asked: “Injector material and processing?”
Lin Ran: “Injector body is stainless steel, nozzle parts in copper alloy.
Fewer orifices than F-1, but each requires extreme concentricity, processed on precision lathes and inspected individually.”
Zhang Xiaoqiang: “Liquid hydrogen low-temperature handling is a challenge; how does the turbopump cope?”
Lin Ran: “J-2 fuel turbopump operates at -253°C, requiring Inconel or 316 stainless steel for impeller and casing.
Seals use labyrinth seals to reduce leakage. Bearing lubrication system cooled by liquid hydrogen to avoid freezing.”
Zhang Xiaoqiang asked: “For testing, how were F-1 and J-2 verified?”
Lin Ran: “F-1 undergoes static ignition test after each assembly, duration equivalent to flight time, about 150 seconds.
Monitored parameters include thrust, combustion chamber pressure, temperature, and vibration.
J-2, being an upper-stage engine, requires altitude simulation tests in a vacuum chamber to verify performance in low-pressure environments.”
The testing methods Lin Ran mentioned were very standard; after hearing them, Zhang Xiaoqiang just reconfirmed the other truly understood. He asked, “What about quality control? Any special inspection methods?”
Lin Ran: “Every component undergoes non-destructive testing.
Injector plate uses X-ray for welds, combustion chamber ultrasonic for cracks, turbopump dye penetrant for surface defects.
After engine assembly, full-system pressure testing.”
Wang Qiang: “If materials are short, like Inconel-X750, what do we do?”
Lin Ran: “Try to find the closest substitutes, like Inconel 718, but must perform thermodynamic and mechanical performance tests to ensure consistency with original design.
Any changes require additional verification.
But ultimately, we need to avoid such situations.
If it’s a funding issue, I can provide the money.
In short, remember, replication is not just copying drawings, but understanding the engineering logic of every design.
Let’s get started.”
In the manufacturing workshop, precision drilling machines were neatly arranged, with cutting fluid smell permeating.
Lin Ran stood by a drilling machine, guiding the engineer.
Injector plate semi-finished product fixed on the workbench, 304 stainless steel surface gleaming with metallic luster.
Lin Ran picked up a depth gauge: “This orifice depth must be precise to 0.1 mm, angle deviation not exceeding 0.01 degrees. See, there’s a tiny burr here; polish with fine sandpaper.”
“Good, Professor, I’ll be very careful.”
Lin Ran used an optical microscope to inspect an orifice, screen showing smooth edges, no flaws.
Lin Ran said satisfied: “This orifice is qualified. All 2832 orifices must meet this standard.”
“So many orifices, each perfect, enormous workload.” Zhang Xiaoqiang following thought.
The engineer asked: “Professor, how to process the copper liners?”
“Copper liners by electrical discharge machining, inner wall roughness Ra 0.4 microns, ultrasonic cleaning after to remove residual particles.” Lin Ran replied without thinking.
Lin Ran inspected a row of orifices one by one, finding one with 0.02-degree angle deviation.
Lin Ran said seriously: “This orifice is unqualified, needs redrilling.
Combustion chamber pressure up to 70 bar; any deviation could cause oscillations.”
Bar is a pressure unit, 1 bar = 100 kPa.
The engineer nodded, readjusting drilling machine parameters.
Lin Ran emphasized again: “Precision is paramount; no compromises.”
After copper baffle processing, the team performed brazing in the vacuum furnace.
Lin Ran supervised the brazing process, ensuring temperature stable at 1093°C.
Lin Ran: “Immediately X-ray after brazing; any micro-cracks could cause failure.”
“Understood, we’ll inspect piece by piece.”
In the vacuum furnace control room, engineers monitored temperature curves.
Lin Ran stood before the display screen; 178 Inconel-X750 tubes neatly arranged in the furnace, brazing filler evenly applied.
Lin Ran: “Heating rate 5°C per minute, hold at 1093°C for 30 minutes, slow cool. Rapid temperature changes cause tube deformation.”
“Program set, will strictly control.”
Vacuum pump hummed, furnace pressure dropping to 10^-5 torr.
Torr is also a pressure unit, 1 torr = 133.322 Pa.
Lin Ran thought: “Brazing is the bottleneck in F-1 manufacturing; any mistake could ruin weeks of effort.”
30 minutes later, cooling began. Furnace door opened, combustion chamber tube walls smooth, no obvious defects.
“Initial check, tubes evenly arranged, no deformation.”
Lin Ran: “Good, immediately ultrasonic testing to confirm weld quality.”
Test results showed welds intact, only one tiny pore; Lin Ran suggested local rewelding for perfection.
In the balance lab, a 1960s-style manual balancing machine was activated.
Lin Ran personally operated, demonstrating impeller calibration.
Lin Ran: “This balancing machine is a replica of the original design. We need to reproduce NASA’s calibration process.”
He installed the aluminum alloy impeller on the machine, started rotation; screen showed 0.3 g-mm imbalance.
Lin Ran: “Need to drill small hole on impeller for correction. Based on phase, drilling position here.”
He marked the position; China Aerospace engineers took turns trying the operation.
“Professor, how to determine drilling depth?”
Lin Ran: “Calculate based on imbalance amount; usually a 0.1 mm deep small hole suffices.
Retest after drilling.”
After three adjustments, imbalance reduced to 0.08 g-mm.
Lin Ran: “Qualified! Every impeller must be calibrated this way.”
Nearby Zhang Xiaoqiang inwardly exclaimed: “The Professor is too proficient?
Even such old equipment used so precisely.”
Zhang Xiaoqiang knew from the moment he received the task that Lin Ran was proficient in Apollo Moon Landing.
Over the past month’s cooperation, Lin Ran’s proficiency was nothing like what he thought.
Zhang Xiaoqiang knew Lin Ran studied in America, knew he was a fanatic Apollo Moon Landing enthusiast.
His idea of proficiency was at most finding some external inaccessible data, knowing some unknown technical secrets.
That was it.
At best, fewer detours in R&D.
But necessary tests, attempts, letting engineers find ways to achieve goals—these steps are indispensable.
Called replication, more accurately replication-style R&D.
At most, some map opened, then exploring on that basis.
R&D itself is like exploration, requiring constant trial and error; replication at most reduces errors.
Even if America now wants to replicate Apollo Moon Landing, remake F-1 engine, they’d still do those 2000+ combustion instability tests.
At least seven or eight years.
Plus other steps, repeated testing and verification.
So, America not restarting Apollo Moon Landing, Commissioners Smith wanting to make a fortune is one thing; replication itself having no cost-effectiveness is another.
This was Zhang Xiaoqiang’s cognition before cooperating with Lin Ran.
But after cooperation, his cognition was completely overturned.
Lin Ran’s performance was less proficiency, more like he knew every detail like the back of his hand.
What’s often one sentence in reports, the underlying principle might take thousands of hours to figure out.
Lin Ran’s so-called proficiency, specifically how to do each step, was broken down and explained on-site to Sixth Academy engineers.
It made Zhang Xiaoqiang question life; if the other weren’t just 24, if a bit older, he’d suspect he participated in F-1 engine R&D and manufacturing.
J-2 injector manufacturing proceeded in another workshop.
Lin Ran inspected coaxial orifice machining; 316 stainless steel injector body fixed on the lathe.
Lin Ran emphasized: “Concentricity deviation not exceeding 0.01 mm, check per orifice with micrometer.”
“Yes, Professor, I’ve checked 10 orifices, all qualified.”
Lin Ran picked up a copper alloy nozzle, inspected the surface.
Lin Ran: “Nozzle roughness Ra 0.2 microns, good.
Keep it up.”
J-2 combustion chamber brazing in another vacuum furnace, 540 316 stainless steel tubes neatly arranged.
Lin Ran: “Brazing temperature 1050-1070°C, heating rate 3°C per minute, hold 25 minutes.”
“Furnace pressure reached 10^-6 torr, program running normally.”
After brazing, combustion chamber tube walls smooth, ultrasonic confirmed no defects.
Lin Ran: “Perfect! This batch of combustion chambers can proceed to assembly.”
Liquid hydrogen turbopump manufacturing in the cryogenic lab.
Lin Ran guided team testing labyrinth seals.
Lin Ran: “Run pump body in -253°C liquid nitrogen for 10 minutes, check sealing.”
“No leakage, bearing temperature stable.”
Lin Ran: “Good, bearings cooled by liquid hydrogen to ensure no freezing.”
In the assembly hall, F-1 and J-2 engine components neatly placed. Lin Ran supervised assembly, guiding bolt torque and gasket installation.
Lin Ran: “F-1 injector plate to combustion chamber connection, bolt torque 50 Nm, gaskets undamaged.”
“Yes, Professor, I’ll check each one.”
During J-2 assembly, Lin Ran spotted a liquid hydrogen pipe joint deviation.
Lin Ran: “This joint deviated 0.05 mm, needs realignment, or it may leak.”
Team quickly adjusted, completed assembly. All components passed X-ray, ultrasonic, and dye penetrant testing, ensuring no defects.
In the test field, F-1 engine fixed on test stand, control room screens showing real-time data.
Lin Ran: “150-second static ignition, monitor thrust, specific impulse, pressure.”
Zhang Xiaoqiang personally served as test commander: “Countdown 10 seconds! 3, 2, 1, ignition!”
Flames surged, thrust reaching 6770 kN, equivalent to 1.522 million pounds, specific impulse 263 seconds, pressure 70 bar.
The engineer monitoring data excitedly said: “Data stable, no oscillations!”
Lin Ran: “Matches Apollo 11 data perfectly in performance.”
Subsequently, J-2 engine testing also went smoothly.
Liquid hydrogen system sealing perfect, combustion efficiency as expected.
J-2 vacuum chamber test, thrust 1033 kN, specific impulse 421 seconds, three ignitions normal.
“Mass 1790 kg, deviation from original 1788 kg only 0.1%.”
Zhang Xiaoqiang added: “We compared Saturn V data; F-1 and J-2 performance perfect match.
Non-destructive testing and pressure pulse tests also passed.”
After leaving the production workshop and returning to the meeting room, the engineer teams cheered, celebrating with water cups as wine glasses.
“Bang bang bang”
“Come in.” Jia Yong said.
“Dean, I’m here to report work.” Zhang Xiaoqiang pushed the door and entered.
