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

On Sunday night, Jiang Ming sat alone in the confidential 502 room and laid out two more documents side by side.

On the left is a summary of the Soviet R-2 guidance parameters, in the middle is the whiteboard derivation record he left at the preparatory meeting of the Fifth Academy, and on the right is a six-page calculation of the vertical distribution of atmospheric density from Qian Xuesen's confidential letter.

The preparatory meeting minutes focused on Earth rotation coupling and gyroscope drift correction. The two percent deviation has been separated from the three inputs: Coriolis term, initial orientation, and integration time.

Tonight, we need to check another line: the atmospheric density correction model in the Soviet summary uses standard atmosphere and fixes the tropopause at eleven kilometers.

Jiang Ming first copied the applicable conditions of the model onto the calculation paper, and then marked the latitude of the Soviet test area next to it. It was around 46 degrees north latitude, which corresponds to the high-latitude inland climate conditions.

In his letter, Qian Xuesen cited the Jiuquan radiosonde records from the Chinese Meteorological Department in 1955, which showed that the summer temperature profile indicated that the tropopause often varied between 13 and 14 kilometers.

Jiang Ming used a ruler to align the two sets of heights. Starting from eleven kilometers, the Soviet model had already transitioned to the stratosphere approximation, but the measured profile in Jiuquan was still in the tropospheric decreasing phase.

Vertical differences of more than two kilometers will change the rate at which density decreases with altitude, and the integral range of aerodynamic drag experienced by the projectile during the ascent phase will also be extended accordingly.

He substituted the velocity, altitude, and reference area of ​​the R-2 ascent phase into the resistance term, and then integrated the results piecewise according to the Soviet 11-kilometer model to calculate the first set of velocity losses.

The second set of calculations used Jiuquan radiosonde data, with temperature, air pressure, and density interpolated at actual altitudes, and the upper limit of integration extended to the summer average at 13.2 kilometers.

The two sets of numbers were initially close, but as the integration continued, the difference gradually accumulated along the square of the velocity term, eventually falling between 0.8% and 1.2%.

Jiang Ming put down the slide rule, rechecked the units and ballistic time, and added the changes in the aerodynamic coefficients in the high-altitude section into the error range. The result was still within the same order of magnitude.

If we only look at the velocity loss deviation of about one percent, it is easy to include it in the parameter margin. However, after it enters the terminal stage of the ballistic trajectory, it will be amplified by the range sensitivity coefficient.

He opened the Soviet-summarized range equations, and substituted the shutdown velocity, trajectory inclination, and remaining flight time into them one by one, thus expanding the lateral dispersion to the kilometer level.

The initial result on the calculation paper fell around 1.5 kilometers. After the seasonal extreme value was expanded, the range extended to both sides, making it impossible to fit in ordinary measurement errors.

Jiang Ming pushed the temporary draft aside, took three blank report sheets, and began to organize the analysis draft that could be directly brought to the demonstration meeting.

The first page draws the temperature and altitude profiles of the standard atmosphere and the measured temperature at Jiuquan, indicating the differences at 11 km, 13.2 km, and the tropospheric lapse rate.

Next, we will derive the tropopause correction, showing how changes in altitude are passed into pressure and density functions, maintaining continuity on the same page.

The second page contains the Jiuquan radiosonde data from 1955, arranged by winter and summer, and then compared layer by layer with the standard values ​​adopted by the Soviet model.

He marked the eleven to thirteen-kilometer interval with a diagonal line, which is the main part that the Soviet model missed after prematurely entering the stratosphere approximation.

On the third page, the revised atmospheric density vertical distribution model is rewritten, and the drag term, integral upper and lower limits, and velocity loss changes are expanded side by side.

The red pen eventually reached the bottom of the page, circling the two lines of conclusion.

When the Soviet R-2 model was used in China's low-latitude test areas, the range error contribution was approximately 0.8% to 1.2%.

The corresponding lateral dispersion contribution of the landing point is approximately 1.5 kilometers, with the specific value varying depending on seasonal sounding conditions.

Jiang Ming checked the three-page manuscript from beginning to end, then took out the two percent drift conclusion from the preparatory meeting and listed the two sources of error on the same sticky note.

The Earth's rotation coupling alters the lateral motion, while an incorrect atmospheric density distribution alters the velocity loss during ascent. Although these two factors enter the ballistic equations at different points, they simultaneously leave system deviations at the point of impact.

If the demonstration meeting only redoes the gyroscope drift pre-compensation table and continues to use the Soviet standard atmosphere, the new guidance scheme will still bring another set of fixed-direction errors into the test.

He turned to the last page of Qian Xuesen's letter, where the message that the Soviet side would provide a more complete parameter package during the preparation of the Fifth Academy was written below an excerpt from meeting minutes.

The complete parameter package will add details such as engine shutdown, lateral stability and gyro pre-compensation. However, if the atmospheric model continues to use the 46°N latitude condition, subsequent calculations will continue around the same assumption.

The more detailed the parameters, the more tables and control items will be involved when making changes.

Jiang Ming did not include this judgment in the formal analysis draft for the time being, but only wrote the three words "parameter package" on the old hard cover memo and drew a circle around it with a pencil.

The standards adopted for the complete parameter package must be clarified at the demonstration meeting before deciding whether this risk needs to be raised on the spot.

The clock on the wall struck midnight, and outside the cubicle, only the sound of the duty officer flipping through the handover book could be heard. Jiang Ming put the guidance materials into a canvas bag and then took out the draft of Theodore von Kármán's reply.

The final section of the unsteady temperature field in the variable cross-section pipe has been derived. The master equation, boundary conditions, and three independent decision points after the temperature potential transformation are all contained in the old hard-cover memo.

He rewrote it on airmail stationery, first explaining that when the thermal conductivity changes with temperature, directly processing the original equation can easily cause the cross-sectional function and the material nonlinearity to become entangled.

Then, a temperature potential function is introduced, the thermal conductivity coefficient is integrated into a new variable, and the position term caused by the variable cross section is retained, so that the main heat transfer equation can be obtained in a separable form.

The first judgment point is the response scale when the inlet heat flux changes over time, and the second discussion is the rearrangement of the axial temperature gradient due to cross-sectional contraction.

The third criterion limits the scope of application of the transformation. If the wall radiation is strong enough to change the form of the boundary conditions, the linearization result must be recalibrated.

Jiang Ming included a derivation entry after each conclusion, without using terminology beyond the scope of currently available knowledge, nor hiding intermediate steps in a vague judgment.

After finishing the last page, he pressed the writing with blotting paper, waited for the ink to dry, folded the letter back to its original creases, and put it into his personal document bag.

The letter also had to be reviewed by Qian Xuesen for its format, while the derivations and technical viewpoints remained unchanged before it could be sent to Pasadena through a top-secret mailbox.

Just as Jiang Ming finished fastening the file bag, there were two light knocks on the door of the cubicle. Comrade Song reminded him of the departure time through the door panel.

"Jiang, leave at 6:30. The car is waiting at the factory gate."

"Okay, I'll put the documents away and leave."

Jiang Ming put the three-page revised draft of atmospheric density into the inner layer of the canvas bag, placed the Soviet parameter summary and the preparatory meeting minutes on the two sides, and checked the document numbers one by one.

After the desk lamp was turned off, only the gray daylight filtering through the window cracks remained in the cubicle. The slide rule and red and blue pencils on the workbench were put away in the drawer.

The cars outside the factory gate had already been inspected, and the drivers were waiting with their dispatch orders in hand, while Comrade Song had the confidential document register tucked under his arm.

As Jiang Ming walked out of 502, his canvas bag was pressed against his side, and the three pages of the analysis manuscript inside gently brushed against the Soviet parameter summary with each step.

In the conference room of the Chengxi Confidential Compound, a complete parameter package bearing Russian serial numbers and a top-secret red stamp is awaiting its first formal review.