Courtyard House: Starting with a 28-inch motorcycle

Everyone nodded solemnly. Breakthroughs in core aerospace equipment are always a matter of national lifeline; how could they dare to treat them lightly?

Fortunately, this group of people has never been picky about the environment. As long as there is a clean laboratory and a few reliable instruments, they can take root and flourish.

The convoy started quietly and traveled through the inky darkness of the night, without lights, sound, or a trace.

Upon arriving at the military research institute, as soon as I got out of the car, a group of veterans with gleaming shoulder insignia came to greet me.

"I've been looking forward to meeting these 'star-hunting people' for so long, and today my dream has finally come true!"

Seven or eight generals gathered around, their expressions sincere and fervent. Although Xiao Yao maintained strict secrecy to the outside world, the military's high command, especially the generals who regularly liaised with research institutes, had long since etched his name into their work notebooks—

To secure the core technology of the US's latest frigate with just a mobile phone distribution rights—who wouldn't be impressed? However, while naval development is still in its early stages, the real pressing issue is the air force—the painful lesson from the South Korean defeat years ago remains etched in their bones. Hearing that Xiao Yao was leading a team to develop a new engine, the old marshal even cancelled his meeting and came specifically to see him. He knew that Xiao Yao's breakthroughs had already propelled China's domestic industry to the forefront of the world; now that the heart of aviation had been entrusted to this team, he finally felt truly at ease.

Xiao Yao shook hands with each of these names from textbooks—generals who had led thousands of troops and built a barrier of mountains and rivers with their blood and flesh. When the old marshal's thin but strong hand grasped his, his palm trembled slightly.

"Xiao Yao, we're all waiting for you."

He didn't say a word, yet his words carried immense weight.

Xiao Yao felt a surge of heat in his throat, his heart pounding in his chest like a drum. The people before him were not cold, lifeless words in the annals of history, but living, breathing pillars of society, who had dedicated their lives to serving others.

The veterans clearly knew his importance and treated this young man with no airs, but rather with exceptional kindness. Knowing his tight schedule, they still made time to come, offering heartfelt encouragement in every word.

Surrounded by a group of distinguished senior figures, who patted him on the shoulder and gave him instructions, Xiao Yao's eyes welled up with tears, and he found himself struggling to speak.

"Alright, let's not keep the scientists from getting to work! They're in good spirits and have a lot of work to do, so let's all go back to our posts—we'll celebrate with a big drink when the good news comes!"

The old marshal spoke in a loud and clear voice, decisive and efficient.

The crowd then dispersed, laughing.

Under the guidance of Commander Li, Xiao Yao's team entered the dedicated laboratory and independent testing chamber.

As soon as I entered, several white-haired academic giants had been waiting for a long time. Hearing that this group of young talents was coming, the old gentlemen specially put down their work, just to see these young people who would shoulder the heavy responsibility of the future, hoping that they would surpass their teachers as soon as possible.

After a few words of encouragement, everyone quickly got to work and buried themselves in organizing the materials.

Su Man went straight to the cafeteria and became acquainted with the logistics manager—from now on, she would collect the team's meals. After all, the pace of scientific research waits for no one, and sometimes it was common to be so engrossed in data that one would forget to eat all day.

After a day, having thoroughly reviewed all the raw data, they identified the first key issue:

The abnormal vibrations that this fighter jet exhibited during high-altitude cruising pose the greatest threat to flight safety.

After in-depth analysis, the problem pointed directly to the engine's core component—the guide vanes.

Even a micrometer-level deviation in such precision components can cause airflow turbulence and thrust imbalance, becoming the culprit that induces body tremors.

The test results came out quickly: the assembly error between the blades far exceeded the design threshold, and some blades even showed directional deviation.

This is very likely the source of the chronic vibration problem.

Xiao Yao quickly realized that the real problem was far more than the outdated blueprints—what they were currently relying on was a piston engine that had long been completely phased out by mainstream fighter jets.

The structure of this type of engine appears simple: cylinder, piston, connecting rod, crankshaft, valve train, propeller reducer, and a cast aluminum housing that encloses the entire engine.

The cylinder is the "firebox" where the air-fuel mixture burns, and the piston bounces back and forth inside. The cylinder head is riveted with spark plugs and also has intake and exhaust valves, precisely controlling the rhythm of each breath.

When running, the cylinder block gets extremely hot, and the outer wall is covered with fin-shaped heat dissipation fins, just to desperately dissipate the heat; while dozens of cylinders are often arranged in a star or V-shaped array on the casing, like a cold metal flower - five cylinders, seven cylinders, nine cylinders... up to twenty-four cylinders; with the same single cylinder volume, the more cylinders there are, the more explosive power.

The piston is violently propelled by the combustion gases, reciprocating rapidly within the cylinder; the connecting rod then transforms this intense thrust into rotational force, transmitting it to the crankshaft; the crankshaft, the heart pump of the entire machine, outputs power while simultaneously engaging the reducer, pulling the propeller to tear through the air and generate thrust; it also drives a host of accessories such as the magneto and oil pump. The valve train, like a strict gatekeeper, precisely controls the opening and closing of the valves in milliseconds, ensuring a full intake and clean exhaust.

This isn't an upgrade; it's like rewinding an antique clock—no matter how much you polish it, you can't achieve the precision of a digital watch. Xiao Yao immediately put down the documents and headed straight for Commander Li's office.

"Commander Li, there's really no need to continue this improvement project. Even if it's tuned to its limit, the ceiling for piston engines is what it is—thrust, response, and high-altitude performance are all stuck at World War II levels. What the old leaders want is combat capability that can compete with the US's new fighter jets, not for our pilots to barely manage to take off by 'grinding' their engines. I heard that the models they sold are using this kind of outdated, unused equipment? The fact that they dare to push it out shows that they've already upgraded to something more advanced. Instead of stubbornly sticking to the old path, we should jump straight to a new track."

He initially thought it was a major research and development project, but after reviewing the technical files, he realized that the so-called "improvement" was nothing more than replacing the horseshoes on a mule cart—no matter how shiny or durable, it couldn't outrun a high-speed train. Without sufficient thrust, you're just a sitting duck in the air: enemy planes can accelerate and leave you ten miles behind, and you won't even be able to catch their taillights.

After hearing this, Commander Li immediately picked up the phone and reported it directly to his superiors.

……

The old leader was engrossed in reviewing documents when his secretary pushed open the door and entered.

"Leader, Division Commander Li Youhong of the Military Region has called urgently, saying he has something important to report."

The old man put down his pen, his brow furrowing slightly: "Xiao Yao and the others have only been at the institute for two days, where did they get this conclusion? It's too fast."

"Bring them in."

The phone is on.

"Sir, Professor Xiao Yao suggests that we immediately start developing a new type of aero-engine—the batch of fighter jets we just imported are still equipped with piston engines from the end of World War II. Let alone being able to meet actual combat standards, they can't even meet basic tactical indicators."

Commander Li's words were concise, leaving room for interpretation: "The project approval is up to you; I can only relay the message."

"Let Xiao Yao answer the phone."

"Hello, leader, this is Xiao Yao." He was right next to Commander Li and reached out to take the receiver.

"Xiao Xiao, let me ask you something—is this engine really completely useless? We can't expect all those planes to be grounded, can we?"

The old man knew very well that the first test flight of the aircraft experienced mid-air vibrations during the handover, and subsequent investigations all pointed to the power system. Although it was unlikely to crash, who would dare to let a soldier risk his life in a "half-crippled" fighter jet?

"Boss, it's not scrap metal, it's a 'misfit gem.' With a few modifications, it's perfectly capable of mounting transport planes and civilian aircraft—fuel-efficient, robust, and long-lasting, it won't show its age even at fifty. But putting it on a fighter jet? It's like putting a horse-drawn cartwheel on a race car—speed is the lifeline on the battlefield, and a difference of ten kilometers per hour can shift the line between life and death by a huge margin."

Xiao Yao spoke slowly and deliberately, yet every word struck at the heart of the matter.

"Good! Well explained! Even I, a layman, understand it." The old leader laughed heartily. "Now I'll make two points: First, new research and development and old system upgrades should proceed simultaneously—our air transport shortcomings are too obvious, so we should make the most of existing technologies; second, the new engine must be developed quickly! I'm waiting to award you medals!" After saying that, he paused, "and handed the phone to Comrade Youhong."

Commander Li took the microphone.

"Youhong, prioritize all materials, manpower, and equipment for Xiao Yao's team at the research institute; put the overall fighter jet design on hold for now, and wait until the new engine is running!"

Commander Li snapped to attention with a standard military salute and hung up the phone.

Xiao Yao returned to the laboratory, the door not yet fully closed, and his voice had already fallen:

"The project has been approved by higher authorities—a new engine, codenamed 'turbo-ramjet hybrid thruster.' The core idea is to make the turbine and ramjet systems 'relay race': the turbine takes the lead at low speeds, and automatically switches to ramjet mode at high speeds, sharing the intake and nozzle, like two legs running alternately."

Specifically, the turbine core and the ramjet combustor are coupled according to different logics, determining the overall engine's maximum speed. When the Mach number soars, the compressor efficiency drops drastically, at which point it is allowed to "rest"—the blades are feathered or the turbine is idling, and the airflow bypasses the turbine directly into the ramjet combustor for continuous ignition. Theoretically, the maximum speed can reach 4200 km/h. Of course, this requires ingenious design: after the turbine section is shut down, the airflow bypasses and directly hits the ramjet chamber; to reduce drag and increase efficiency, the two flow paths must be coaxially connected in series and tightly interlocked.

As he spoke, he sketched a rough outline on the blackboard—the lines were bold, yet the structure was clear. The drawing was taking shape, the direction was set, and the next step was to break down the task: who would tackle the hot-end components, who would tackle the aerodynamic layout, and who would tackle the material's temperature resistance limits…

The tough challenge Lin Shiyue faced was the deep reconstruction of the turbofan's thermal cycle: embedding a dual-module system of indirect cooling and regeneration. The regenerator is the "thermoregulation center" of this system. When a fighter jet is at full load, the core airflow temperature exceeds 900K. If the regenerator cannot withstand the pressure, the transmission is unstable, or there are leaks, the entire engine will be as weak as if it were lacking oxygen—it is the real technical bottleneck of the indirect cooling and regeneration turbofan.

Xu Wenxin and Wu Rui focused on upgrading and iterating existing precision equipment, especially the entire process of engine testing—every step is subject to the utmost precision; the slightest deviation could cause the entire engine to fail.

As soon as the tasks were assigned, Su Man rushed into the lab and called for lunch. Everyone had been busy since last night, and their stomachs were growling with hunger.