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

After the first digit is dropped, Jiang Ming continues to calculate along the sensitivity coefficient, transmitting the velocity loss deviation during the ascent phase to the shutdown state and the terminal phase of the trajectory.

The Soviet model underestimates the tropopause by about 0.8 percent in winter conditions, and the deviation widens to 1.2 percent after the tropopause rises in summer.

He used red chalk to frame the two seasonal extreme values ​​respectively, and wrote the sensitivity coefficient of the velocity error in the range equation below.

The loss of speed will change the actual speed and trajectory angle at the shutdown point. After being amplified by the remaining flight time, the lateral impact point deviation will fall between 1.2 and 1.8 kilometers.

When the red box is closed, the junior general looks down and opens the precision index page in the parameter package, comparing the landing point distribution requirements marked by the Soviet side with the results on the whiteboard.

The range of 1.2 to 1.8 kilometers already accounts for more than one-third of the required circular error probability, while the summer extreme value approaches an even higher engineering risk range.

The ballistics team began to recalculate the transfer coefficients, moving the slide rule back and forth on the paper. The final range they obtained differed from the whiteboard only by the last digit.

Near the whiteboard, a returned expert flipped to the page on winter sounding in Jiuquan and pointed to several sets of lower tropopause records.

"The tropopause varies with the seasons; in Jiuquan, it can drop to 11 to 12 kilometers in winter. Wouldn't making adjustments year-round overload the model?"

Jiang Ming moved the winter data to the edge of the whiteboard and remarked the altitude layer around twelve kilometers.

"The launch window cannot be entirely concentrated in winter; seasonal conditions must be included in the design scope, and the summer side cannot be removed from the model."

He added a density integral next to the winter profile and calculated up to twelve kilometers along the same set of ballistic parameters.

"Even if the tropopause drops to twelve kilometers, it is still about one kilometer different from the Soviet assumption, and the velocity loss integral will be underestimated by 0.4% to 0.5%."

Write the conversion result in red chalk on the next line.

"After the data is transmitted to the landing point, the error contribution is about 0.6 kilometers. This amount still needs to be included in the guidance error allocation."

The returning expert looked down at the winter records, changed the pencil mark next to the Soviet 11-kilometer stratification to "to be corrected," and then pushed the page to the ballistics team leader.

Ren Xinmin looked up from his blank notebook, his pen pointing to the ballistic equations in the center of the whiteboard. His first question did not dwell on the source of the error.

"If the atmospheric density distribution is corrected, how many terms in the guidance equations need to be modified?"

Jiang Ming erased a blank space at the bottom of the whiteboard, rewrote the complete ballistic equations in separate lines, and then used red chalk to mark all the parts containing atmospheric density.

"The resistance level needs to be updated, as it directly determines the speed loss during the upward phase."

The second mark falls in the lateral motion equation, where density and lateral aerodynamic coefficients work together to affect attitude deviation and lateral velocity.

"The lateral force term also needs to be updated; otherwise, the aerodynamic response used in the lateral stability calculation will still use the old density."

The third thrust loss correction is located in the engine operating section. The jet flow and external pressure conditions will change with the altitude model, thus affecting the actual thrust integral.

"The engine thrust loss correction term also needs to be recalculated, and the density models used for the three inlets must be consistent."

Ren Xinmin copied the three items into his notebook in turn and drew connecting lines between drag, lateral force, and thrust loss.

"Regarding the revised parameters, do you suggest directly substituting the measured radiosonde data, or establishing an empirical model suitable for low latitudes?"

Jiang Ming divided the whiteboard into two columns on the right side: the left column for actual measured data and the right column for seasonal empirical models.

"Actual sounding measurements can reflect the temperature, air pressure, and tropopause position on the day of launch, and the accuracy is high after substitution. However, sounding and data processing must be completed before each launch."

He listed the fitting terms for season, latitude, altitude, and density in the right column, and wrote the error band at the end of the model.

"Empirical models facilitate overall design and routine simulations, and each subsystem can also perform calculations around a unified benchmark, but they retain fitting errors."

Ren Xinmin looked at the two columns of conditions and moved his pen to the bottom of the page.

Which one are you going to choose?

"By combining the two, we first established a seasonal empirical model of Jiuquan at low latitudes, which will serve as a benchmark for guidance design and ballistic simulation."

Jiang Ming connected the two columns to the same correction line using arrows.

"Before launch, we use the sounding data from that day to correct the temperature profile, tropopause, and density stratification, so that the real-time results cover the seasonal average deviation in the reference model."

"After the sounding data arrives, which parameters need to be regenerated?"

"The drag integral table, the lateral aerodynamic correction table, and the thrust loss table all need to be updated, and the shutdown speed and the planned trajectory also need to be reviewed."

Ren Xinmin continued writing for a few more lines, then capped his pen and tapped the table twice with his finger before turning to Qian Xuesen, who was sitting at the head of the table.

"This direction requires the integration of meteorological data and ballistic simulation. The overall team can connect with it to first determine the data format and interface."

Qian Xuesen nodded, his gaze shifting from the two atmospheric profiles on the whiteboard to the ballistics group's seats.

"Meteorological data is accessed uniformly by the overall team, the guidance team is responsible for the model and correction table, and the ballistic team performs cross-calculation of the two sets of results."

He picked up the agenda, wrote "re-demonstration" next to the atmospheric density model item, and added two conditions: seasonal baseline and sounding of the day.

The major general folded out the markings on the atmospheric model page from the parameter package, then took the military requirements group's stamp book and turned to the section awaiting signature.

"The atmospheric density model part of the Soviet parameter package will not be directly referenced for the time being."

As he spoke, he pulled the parameter page out of the folder and placed it next to Jiang Ming's three-page analysis draft.

"The guidance group will first come up with a revised plan suitable for the Chinese test area. After the overall group and the ballistic group complete the review, the official benchmark will be determined."

The security officer then stamped the parameter catalog with a "to be reviewed" stamp, crossed out the mark indicating that it was originally intended to be directly referenced, and filled in the guidance group's revision number.

The complete parameter package from the Soviet side is still used as the basis for system verification, but the atmospheric model has been removed from the list of direct adoptions, and subsequent groups must wait for the new Chinese condition model.

Before returning to his seat, Jiang Ming handed the three-page analysis draft to the security officer for filing, while leaving the Jiuquan sounding record next to the whiteboard for the ballistics team to continue recalculating.

The meeting was about to move on to the engine shutdown signal logic. Ren Xinmin flipped back to the page of his notes and wrote two more lines below the original three corrections.

As Jiang Ming passed by the corner of the table, he could only make out his own name in the first line, followed by "Deputy Chief Engineer of the Guidance Group"; the second line read "Boundary Layer, Atmospheric Density and Ballistic Sensitivity," and the three words were connected by a horizontal line to the end "Systems Engineering Judgment."

Ren Xinmin folded a corner of the page, then waved to the meeting secretary and pushed over the itinerary that was originally scheduled to leave in the afternoon.

"The afternoon train has been moved to a later date; I'll stay and participate in the overall interface discussion."

The meeting secretary took the itinerary and added his name to the afternoon agenda.

Qian Xuesen had already turned to the next chapter of the parameter package, and the engine shutdown delay table had been placed in the center of the long table. Ren Xinmin placed his notebook next to the parameter table and flipped to the blank pages that had been there all afternoon.

Just then, the tea break bell rang from the other end of the corridor.