Chapter 1305: Research and Development Generation, Pre-Research Generation

Zhang Pinsheng looked at the other people for a while with an unkind expression.

Then, perhaps because he felt that continuing the confrontation like this was not an option, or perhaps because out of the corner of his eye he caught sight of Chang Haonan's name on the front page of the document, in short, he took the lead in breaking the stalemate, pulling the technical document lying next to him, and spoke in a tone of voice Toned down a bit:

"From a technical or safety perspective, it is impossible for me to allow you to start the engine in the microwave anechoic chamber... However, we have considerable experience in the field of radar testing, and we may be able to come up with a feasible alternative based on your specific needs."

Except for Liu Yongquan, who brought the information, everyone else was struck by the keyword "plasma invisibility" in the summary, and they didn't even have time to take a closer look at the key content behind it.

Now that they were reminded by Zhang Pinsheng, they all came back to their senses.

Then there was the sound of flipping through papers.

Compared with aircraft overall design units that have been thinking about pre-research on stealth technology almost twenty years ago, the aviation field has basically only started to consider reducing signal characteristics in the past year or two, and the research focus is still on infrared signals. .

Therefore, the content relayed by Liu Yongquan may not be accurate.

It is more reliable to look directly at the written requirements document.

As expected, the document details the generation and control methods of the plasma sheath, as well as the original test purpose——

"Under the operating conditions of the engine and plasma generator, measure and compare the RCS (σ)-angle (θ) relationship curves corresponding to different magnetic control algorithms, paying special attention to the changes in the tail of the aircraft (within the 80°-100° range) situation to determine the volume coverage and frequency coverage accuracy of the magnetron plasma sheath..."

Zhang Pinsheng recited the last section word for word, then lowered his head and thought for a moment:

"In other words, the main purpose of this test is comparison, and does not particularly pursue the comprehensiveness of the value itself?"

Liu Yongquan nodded:

"The engine participating in the test itself is only a technical verification model improved on the turbofan 10A. It is not the final product that will be delivered to the fourth-generation fighter project, so the RCS results do not have much practical value, as long as it can verify several controls The effect of the plan is enough..."

At this point, perhaps because I was worried that the other party would over-understand, I added another sentence at the end:

“Of course, the deviation cannot be too outrageous, at least the order of magnitude must be ensured... In addition, although it is not necessary to provide a full-band frequency sweep measurement from L to Ka like the American lintek5000 system, the wavelength selection of the test signal must also be ensured. Set between 2.5cm and 7.5cm, and the bandwidth cannot exceed 0.2cm..."

Before he could finish speaking these contents, Zhang Pinsheng's originally stiff expression relaxed visibly:

"If that's all, then I have an alternative here..."

Including Yang Wei, everyone's attention was attracted to him.

Even Zhang Pinsheng, who has rarely seen big scenes, felt nervous for a moment:

"Ahem——"

He cleared his throat:

"Old Lin should know this... In the early years, when we didn't have this large microwave anechoic chamber and frequency scanning measurement radar, in order to ensure that the J-7IIS and J-8IIS could conduct large-scale field omnidirectional scattering tests, we renovated it on the top of the back mountain of the old park. A dynamic test bed…”

Lin Jihong's eyes showed confusion for a moment, but he quickly reacted and turned into surprise:

"Hasn't that test bench not been used for several years... And I have the impression that the electromagnetic signal source was originally used as a 342 radar removed from a warship. The bandwidth accuracy may not meet the requirements of this test. Bar?"

Zhang Pinsheng immediately explained:

"There is indeed one that has not been used for six or seven years, but don't forget that because time was tight at the time, that test bench was not equipped with an aircraft turntable. Instead, a circle of tracks was laid around the fixed bench, and then the radar was installed Moving around the aircraft in orbit..."

Liu Yongquan and Yang Wei had not experienced the verification of stealth technology in the 1990s, but after being confused at first, they quickly captured the key.

"So...it still works?"

Liu Yongquan asked with concern.

He didn't know much about radar, but he also understood that the omnidirectional detection platform built on the top of the mountain meant that the test background was relatively clean.

After all, the atmospheric absorption of electromagnetic waves between 2.5cm and 7.5cm is weak. Even if the test is not as good as a microwave anechoic chamber surrounded by electromagnetic absorption cones, it is at least similar to the actual environment.

Zhang Pinsheng nodded:

"The backend systems are all underground. Although they are a little out of date, they are sealed in strict accordance with the rules and regulations. All we need to do is recheck and replace some necessary consumables. Only the broken radar used before did not work. The sunbed is definitely not working anymore, it will take some time to replace it with a new one.”

Yang Wei also intervened at this time and began to brainstorm together:

"As for the new radar, maybe you can just dismantle a 1473... There is no need to contact the Electronic Technology Group separately. There are many reserves waiting to be installed on the aircraft at Rongfei. I can transfer them with my signature... "

However, Zhang Pinsheng waved his hand and rejected his proposal:

"Fighter radars... or most modern search/fire control radars are broadband radars, which do not meet the test requirements."

"That……"

Yang Wei's expression froze for a moment.

"We have several 5cm wavelength 172B precision measurement radars, which we used in the first half of the year when doing track measurements for the Flight Test Research Institute."

Zhang Pinsheng replied:

"Of course, because it is a conventional radar, it does not have the ability to directly measure the absolute value of RCS. However, the relative measurement method can be used, which is to use a metal ball as a calibration body to obtain the relationship between the precise value of RCS and the signal echo intensity, and then according to the target The power or voltage ratio obtained by the test can be used to calculate the reflection area of ​​the target. The key is that the bandwidth is very narrow and meets the requirements of RCS measurement..."

"..."

After some discussion, everyone looked at each other again.

But this time, the atmosphere was no longer as tense as it was at the beginning.

Check out the 16-9 book bar and see the correct version!

"Director Zhang, how long will it take to do all the work you just mentioned?"

Liu Yongquan asked:

"There are currently only two modified 10A turbofans at the 410 Factory. I need to arrange the transportation time as accurately as possible..."

The design and development of the 10G turbofan is not in a hurry these days, but Chang Haonan has specifically asked before that the relevant test parameters of the plasma sheath are related to other projects at hand, so he still has to calculate the test cycle. .

"We actually don't have much to do here. It will take about a week to ten days..."

When Zhang Pinsheng said this, he looked at Yang Wei and Lin Jihong next to him:

"The main thing is to see if Rongfei can put your engine into the model..."

Yang Wei nodded:

"Even if the model is inserted, it cannot provide working conditions for the engine. It is better to directly modify a J-10S prototype, just like the J-7IIS, and fix the aircraft on the test bench to start the engine directly..."

"..."

…

Half an hour later, the group left the conference room happily.

However, after the meeting, Yang Wei and Lin Jihong specifically stopped Liu Yongquan:

"Mr. Liu, stay here for now."

As the three of them deliberately slowed down, they soon fell behind the large group of people.

"I just took a look at the document and it mentioned that the control method for the plasma sheath is to use the induced magnetic field equation to solve the induced magnetic field, combine it with the induced current to obtain the Lorentz body force, and then add a correction term that reflects the electromagnetic effect to the turbulence The modified two-equation model of turbulence is obtained from the equations to simulate the classic Hartmann magnetic fluid flow..."

In just a short period of time, Yang Wei extracted the key contents, and under the premise of dual-purpose, it is enough to show his strong ability:

"So, is it possible to introduce part of the plasma to the front of the aircraft and then install magnetic control equipment on the outer edges of the wings or canards to reduce the additional radar reflections generated during the movement of the operating surface?"

As soon as he finished speaking, Liu Yongquan was still thinking, but Lin Jihong, who was walking on the other side, subconsciously stopped:

"Mr. Yang, did you say at the meeting the day before yesterday that... we should avoid frequent use of the active control system as much as possible?"

"This project now...it is indeed the case."

Yang Wei smiled and nodded:

“But I’ve been thinking recently, what should the next-generation product look like after the fourth-generation aircraft enters service?”