I started with a ship full of max-level veterans, and I'm just a complete noob.

Several hours after the military train left the Gobi Desert, its wheels were already on the Longhai Railway line, and vibrations from the seams were transmitted along the floor into the six shock-absorbing boxes.

Old Sun snored against the corner of the box, his toolbox tucked between his legs, his appointment scroll inside, and his medal box wedged between his micrometer and his tobacco pipe.

When they arrived, the equipment in the box had not yet been tested on the battlefield. Everyone guarded the parameters and contingency plans, and even while sleeping, they took turns checking the lead seals.

Now the list is covered with frontline acceptance stamps, and the vehicle has also been loaded with K-band fragments, the Lightning-7 manual, and a collective second-class merit certificate.

On the other side of the folding table, Fang Xudong sorted through the photos of the constant humidity chamber one by one, dividing the German formulas into three groups: resonant cavity, cathode, and magnetic field parameters.

The original document was sealed in an adjacent carriage, and he had to add the time to the borrowing form every time he turned to a page of the copy.

"Twenty-four gigahertz, eight-cavity structure, but the pulse is narrower than that of Source Thunder-1."

Fang Xudong circled the water-cooling jacket outside the anode block with a pencil and pushed the sketch in front of Jiang Ming.

"If it is aligned with the receiver preamplifier, the short pulse can deliver peak power before the input protection is activated, and existing radar stations will not even be able to detect the carrier wave."

Jiang Ming checked the magnetic field units and appended the three pulse records intercepted by Aksai to the sketch.

"The frequency is still drifting, and the coupling verification in the mine can only be completed by using underground pipelines. The antenna and power supply have not been miniaturized, so they cannot be taken out to the field for the time being."

Fang Xudong wrote down broadband detection, harmonic mixing and crystal protection on the pre-research page, and then marked the domestic material restrictions one by one.

"Give them three months, and those two gaps might not still exist."

The pencil stopped at the broadband detection section, and he pressed the corner of the paper with his fingertip.

"When we get back to Beijing, we need to set up an alarm system first. Even if we can't stop it, we have to hear it first."

The location and quantity of the second piece of equipment have not yet been determined, so it can only be listed as the highest risk condition and cannot be used as a ready-made parameter.

Jiang Ming put away the spectrum copy, leaned against the car window, closed his eyes, and let his consciousness sink into the bronze pages of the book.

The gray cracks around the von Kármán node have doubled in size, revealing academic context behind them, though specific calligraphic works remain blocked.

The node only recognizes complete technical exchanges; a connection is established by sending a letter, and the exchange is closed only by sending the first reply.

The sealed knowledge cannot be accessed, and the system does not provide any derivation hints. The answer can only come from Qian Xuesen's lecture notes and Jiang Ming's existing mechanics foundation.

The first question concerns the effect of rough walls on unsteady boundary layers.

He outlined the scale relationships and incorporated the local disturbances caused by the movement of sand grains into the model.

The inversion propagation in Aksai is an electromagnetic problem, but the sand grain lifting process provides real flow conditions and can be transformed into an example of boundary perturbation.

The second question discusses how variable cross sections affect the disturbance path.

The variable cross-section adjustment adopted during the engine room crisis perfectly complements the engineering background.

The derivation framework gradually took shape, and the public theory and front-line data were processed separately. After the final draft was sent to Beijing, it was submitted to Qian Xuesen for review.

The crack remained unchanged.

The wheels rolled across the long bridge, the vibrations subsided, and Jiang Ming pulled the pages out of his book, the graph paper on his lap still in place.

Comrade Song sat by the connecting door checking the checkpoint table, a pistol hidden inside his cotton-padded coat, his gaze frequently falling on the seal on the door.

"Xi'an will replenish water for 20 minutes. The security compartment will remain in place and under guard. Maintenance personnel will first check the work order and then verify the temporary credentials."

Jiang Ming put Theodore von Kármán's letter back into his personal document bag.

"Where is Director Wang?"

"The train was reorganized four hours in advance. Meng Dechang and the technical supervisor were escorted in separate vehicles, and the security department temporarily changed the route."

At this time in Beijing, the sealed-off escort vehicle had already entered the western part of the city, with iron plates sealing the windows, and a guard vehicle at the front and back.

Director Wang sat in the back row, with a secure box containing the burned secret letter on his lap, a short chain fastening his wrist to the lock.

Meng Dechang was sent to an underground interrogation site, and the Grey Pigeon case file was immediately sealed. The materials related to the No. 5 figure were split into three copies for registration.

The burned pages were kept by Director Wang personally, while the Lightning No. 7 manual was sent to the forensic laboratory in a separate vehicle; the two core pieces of evidence did not travel the same route.

After the iron gate closed, only a copy of Zhang Shouzheng's inspection stamp and two train ticket stubs remained on the table.

"Tell me about the material verification in 1949."

Director Wang flipped to the signature column, but there was no mention of the mine shaft or the burned confidential letter.

"Who handled the goods, from which station were they transferred, and in chronological order."

Meng Dechang stared at the photocopy, first naming two warehouse workers who had long since died, and then shifting the responsibility for the transfer to an old department that had been dissolved many years ago.

Director Wang did not interrupt, but simply drew a horizontal line after each name.

The old case, the supply chain, and the source of technology were investigated separately, and the fifth person in charge was still hidden in the document under the table.

In another courtyard in the city, the curtains of an unmarked office were drawn, and the ashtray was overflowing with cigarette butts.

After receiving a call from an insider in Lanzhou, the man at the table learned that the mine had been breached, Meng Dechang had been arrested, and the transport route had been taken out of surveillance.

"Meng Dechang has fallen, the Lanzhou call has been stopped, and all old contacts have fallen silent."

When asked about old files in Beijing, the person on the other end of the phone opened the personnel index and stopped at the recent transfer records of the Third Electronics Factory.

"The files are sealed; whoever touches them first will be the first to be exposed."

After hanging up the phone, he took out half of an old seal from the drawer. Only a small radical remained on the seal face, and the break was clean.

The person by the door took Jiang Ming's file. The face in the factory entry photo was young, and his resume was thin, but his recent achievements pointed to several broken lines.

"Start by checking the schools in the United States, then check the list of returnees, the transfers at the Third Electronics Factory, and their daily routes separately."

"Should we handle it according to technical objectives?"

The man pushed the file back under the lamp.

"The danger level has been raised to the top three. Contact restrictions have been lifted, and we await further instructions."

The order circulated only within the hospital, and neither Jiang Ming nor Director Wang received the news.

The military train pulled into Xi'an Station, its whistle trailing behind the station canopy, and the water hydrants had already been moved to their water replenishment positions.

Comrade Song first checked the door seals, then verified the platform security through the observation hole, and the railway security personnel guarded both ends of the exit.

A maintenance worker carrying a tool bag walked along the side of the train, his hat brim covering his forehead, and a temporary locomotive depot badge hanging on his chest.

He inspected the axle boxes of two ordinary carriages, but when he got near carriage number nine, he changed his route and headed straight for the connecting step.

Comrade Song only opened the inner door a narrow crack.

"Pass in the work order, and move the person behind the yellow line."

The maintenance worker handed over the folded papers, his body still moving towards the door, when his tool bag bumped against the pedal, making a metallic clanging sound.

Comrade Song scanned the train number and the date stamp, then sealed the door and bolted it shut. Through the observation hole, he signaled to the platform guards to stop.

The work order required inspection of the brake hoses in car number six, but the issuance date was one day earlier than the current train formation.

"This is carriage number nine. Please step back and wait for the duty officer to verify your information."

The maintenance worker lifted his tool bag and pointed to the area below the connection point.

"They reported a drafty roof ahead, I'll just take a look and leave."

"The pressure in carriage number nine is normal. Please explain the work order first."

The guards at both ends began to close in, and the maintenance worker retreated to the yellow line, reaching for his badge in front of his chest.

The on-duty staff who arrived at the scene opened the roster and found that there was indeed someone with the same name on duty, but the age in the photo did not match the ear shape.

"Take off your hat and put down your tool bag."

The man turned toward the water crane, quickened his pace, and the bottom of the bag made a metallic sound again.

Comrade Song got off the car from the other side, walked around the connecting section that blocked the passage, and gripped the handle of his gun inside his coat with his right hand.

"Place the bag next to the sleeper, hold your documents over your shoulder, and don't move."

The man glanced at the guards on both sides and had no choice but to put down his tool bag.

The bag opened to the ground, revealing a wrench and measuring tape that rolled out halfway, and a camera wrapped in black cloth.

The lens was equipped with an extended focal length tube, and there was still half a roll of film left inside the camera body, which exceeded the requirements for the maintenance work.

The guard restrained the man by putting his hands behind his back. Comrade Song put on gloves, opened the document holder, and pulled out a thin piece of paper from the inner compartment.

The paper showed the train's formation sequence, only marking carriage number nine, the constant humidity chamber, and the young technician; the name column was blank.

"The person will be detained in a separate location, the evidence will be sealed, and the interrogation results will only be reported to the designated number in Beijing."

The whistle signaling the end of the water replenishment sounded, and Comrade Song returned to the carriage, checked the door locks again, and moved his seat between Jiang Ming and the connecting door.

Jiang Ming finished reading the copy of the compilation paper.

The paper had no name on it, only the number nine carriage, the constant humidity box, and the young technician were marked. It was not yet possible to determine whether the other party was after the fragments, the letter from overseas, or him personally.

"All subsequent stops will be cancelled, the constant humidity chamber will be sealed with an additional lead seal, and a guard will be assigned to Engineer Fang."

Comrade Song crossed out the activity schedule on the site list.

"This carriage was used for wartime escort. Before arriving in Beijing, we would knock on the door and give a secret signal."

The train restarted, and the Xi'an platform moved backward.

The fake maintenance worker was taken to the railway security room, and the film reel was sent to the darkroom for safekeeping.

After hearing what had happened, Lao Sun immediately dragged the Yuanlei No. 1 shockproof box to the inside of the carriage; Fang Xudong also put away the K-band photos and applied a layer of sealing wax to the box lock.

Comrade Song rechecked the magazines, changed the code for the next stop, and increased the number of guards outside carriage number nine to two.

After that, the train doors were not opened at any of the stations along the route, and all water replenishment and maintenance were carried out in isolation and verified by railway security personnel.

The wheels passed through a series of road junctions shrouded in the night, the clattering sounds carrying eastward.

The overseas letters in Jiang Ming's personal file folder remained untouched, and the name column on that collage sheet remained blank until the train approached Beijing.