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

Jiang Ming stepped across the conference room threshold, first bowed to the major general, and then quickly walked to the wide wooden table by the window in the back row.

Ren Xinmin has arranged the latest round of wind tunnel comparison films, which have been washed and enlarged, according to the Mach number range. Next to each film is the corresponding Jiuquan radiosonde record summary and the overall group input parameter card. The three columns of data cover the low Mach subsonic range, the transonic transition range, and the high Mach supersonic range from left to right.

At the main table in the front row, Qian Xuesen was responding to Vasily's question about the meeting's delay in a steady tone. He mentioned the maintenance of equipment power supply and the adjustment of safety procedures, using precise but not aggressive language, keeping his diplomatic remarks at a level that would allow the other party to sit back down.

Vasily's translator translated the text sentence by sentence. After listening, Vasily, though still with his lips pursed, eventually pulled out a chair and sat down again, followed by his three technical deputies.

The front of the venue temporarily returned to a state of apparent quiet.

Jiang Ming took out a magnifying glass from the document bag, bent down and began to examine the high Mach number aerodynamic decay curve submitted by the Soviet side point by point. The frame of the magnifying glass moved slowly along the curve. Every time he passed a marked data point, he wrote down the coordinate value and slope direction of that point on the draft paper next to him.

Ren Xinmin sat opposite him, holding another magnifying glass to check the pressure distribution contour lines on the wind tunnel film. The two of them each guarded an independent data channel, without interfering with each other or exchanging intermediate results. Only when a certain value was abnormal would they push the draft paper in front of each other.

Jiang Ming's camera stopped on a curve near Mach number 2.5. Su Fang's data in this range showed an extremely smooth descending arc with a uniformly decreasing slope and continuous curvature, which looked like an idealized decay model in textbooks.

He moved the magnifying glass away and started by reversing the process from the three contour lines on the film, spreading the pressure distribution along the circumference of the projectile, and then deducing the state of the boundary layer according to the separation criteria.

In the subsonic range, the boundary layer adheres closely to the surface of the projectile, with uniform contour line spacing, matching the Soviet curve. However, once it enters the transonic mixing zone at Mach 2.5, the pressure gradient on the leeward side of the projectile should experience a rapid rise due to adverse pressure. The boundary layer will begin to separate at this point, and crossflow vortices will form asymmetric shedding downstream of the separation point. Lateral pressure concentration leads to abrupt changes in the position of the pressure core.

Physically, this sudden change corresponds to a dramatic jump to a maximum value on the lateral torque coefficient curve.

The curve of the Soviet version, however, at this point looks as if it has been sanded, with all the sharp undulations smoothed out into a gentle transition.

Jiang Ming picked up a pencil and wrote down the derivation formula of the separation critical point in the blank space of the draft paper. Starting from the reverse pressure gradient parameter, he substituted the incoming flow conditions and projectile geometric parameters measured in Jiuquan and gradually calculated the lateral force increment after the crossflow vortex detached.

As he wrote the final result on the right side of the equals sign, he turned the draft paper ninety degrees and pushed it in front of Ren Xinmin.

That value corresponds to an aerodynamic deflection angle of three degrees.

Ren Xinmin was checking the spacing of contour lines on the wind tunnel film when his gaze fell on the draft paper and lingered for a few seconds. Then he placed the magnifying glass on the table, braced his hands on the edge of the table, leaned forward, and started to check each item again from the first line of the derivation.

He first tried to use the precession margin of the gyroscope to counteract the three-degree deflection angle, substituting the projectile's spin rate and precession period into the stability equation. After calculating twice, he put down his pencil, his face losing its color and replaced by a grayish heaviness.

Once a three-degree deflection angle is triggered in the transonic range, the corrective torque of the control surface simply cannot respond within the time scale of the aerodynamic center jump. The control system will treat this sudden deflection as a short-period disturbance and integrate it, and the direction of integration happens to be consistent with the yaw direction. By the time the control surface reacts, the error has already been amplified into the calculation of the impact point in the terminal phase of the trajectory.

Two ballistics experts who had returned from abroad and were sitting next to Ren Xinmin noticed the change in his expression. They leaned closer to look at the negatives and draft paper. The older one ran his finger along the derived integral path, and beads of sweat began to appear on his forehead. He shook his head repeatedly and muttered something in a low voice. The gist of it was that once a deflection of this magnitude was triggered in the transonic speed range, it could not be corrected by any passive stabilization method.

In a corner of the conference room, a logistics staff member in charge of lighting control bumped his elbow on an enamel teacup on the edge of the table while checking spare light bulbs. The teacup tipped over and broke into two pieces, the sound of which was amplified in the tense environment.

The experts in the front row all turned their gazes toward the source of the sound, then quickly looked away.

Jiang Ming incorporated the three-degree deflection angle into the ballistic full-segment integral table under specific monsoon conditions in Jiuquan, and used the lateral force increment triggered by crossflow separation as an input term, integrating it along the flight time from the transonic segment all the way to the end of the trajectory.

The integral results corresponded perfectly to the three rightward contraction trajectories he had previously made in the data room. The reason why the Su Fang smoothing matrix caused the dispersion to always converge in the same direction under different wind fields was that it removed the separation jump in the Mach 2.5 interval and replaced the real aerodynamic fracture with an artificially constructed continuous curve.

The missile itself has a crossflow separation defect in the transonic range. This defect may have been tolerable under the weak wind conditions of the Soviet high-latitude test range, but it would be triggered to a lethal level by the sideslip angle in the strong monsoon environment of Jiuquan. In order to cover up this problem, the Soviets chose to tamper with the parameters rather than modify the missile design.

Jiang Ming wrote the complete logical chain on a piece of draft paper, starting from the first version of the Soviet Union that retained the true fluctuations, the second version that reduced the amplitude, and the third version that smoothed out the residuals along with the direction of reversal, all the way to the end point where the contraction direction was fixed and the dispersion was disguised as a stable margin. Each step of the deduction was marked with the corresponding Soviet revision date and Jiuquan sounding record number.

Vasily tapped the table again on the front row, and the interpreter loudly reminded the Chinese delegation to immediately proceed to the parameter freeze signing process, claiming that the authorization period of the Soviet technical committee was about to expire.

Jiang Ming clipped the calculation draft to the title page of the official report with a paperclip. After confirming that all derivations could be independently reproduced from publicly available data, he closed the report and put it into a file bag.

He glanced out the window; the sky was already a deep gray, pressing down on the tops of the buildings. He asked Ren Xinmin for a cigarette in a low voice. Ren Xinmin took one out of his pocket and handed it to him. Jiang Ming didn't light it; he just held the cigarette to his nose and smelled the tobacco, letting the bitterness of nicotine push away the drowsiness accumulated from continuous calculations from his temples.

Suddenly, the chandelier above the main table in the front row turned on one level. Qian Xuesen stood up to signal that the meeting was about to proceed to the technical demonstration phase. Vasily then left his seat, beckoned three technical deputies, and hung three Russian parameter summary charts on the whiteboard one by one.

The heavy roll of paper hung down along the counterweight rod, its dense curves, symbols, and numbers filling the front of the venue. The Soviet version number was circled in red in the lower right corner, the ink so bright it was almost blinding.

The major general sat in the main seat, tapping the armrest of his chair with his right index finger. His gaze shifted from the first image to the third. The Russian abbreviations needed to be translated and explained one by one, as any misinterpretation could fall into future guidance commands.

Once the last counterweight bar was stabilized, Vasily turned and glanced over the Chinese representatives' seats, opened the speech outline in the red mud dossier, and immediately put the number of live-fire tests at the Kapustin Yar test range on the table.

"This model has undergone dozens of live-fire tests, covering the engine operating phase, free flight phase, and terminal correction phase, and all deviations are within the design tolerance."