The military-industrial scientific research system of the academic master.

Chapter 1302 Must surpass F22!

That evening.

Located in the large conference room on the top floor of Building 611.

More than half of the core members of the fourth-generation fighter research and development team are gathered together, each with two test result summaries in front of them.

Although it is a summary, because aerodynamics and microwaves are both of great importance and can be said to be the two aspects that determine the key performance of the new generation of fighter jets, even after being refined, they are still two thick volumes.

The dozen or so printers in the archives room worked almost until they started smoking in the afternoon, barely making it to the meeting time.

Of course, some of the key content is also being displayed on the large screen in the front.

At this time, Lin Jihong was sitting in the first seat on Yang Wei's left, introducing the corresponding part to everyone.

RCS is never a specific number. The "RCS value" that people usually see in the data is often just the most ideal situation at a specific angle, or the average result within a certain angle range.

If you really want to objectively demonstrate the stealth performance of an aircraft, you need to use an expression similar to the physical field, centered on the target, and present the reflection signal intensity at different angles in three-dimensional space.

The presentation of this result is quite complicated, and even with the report in hand, it is difficult to fully grasp the situation at once.

As the person in charge of tracking the entire microwave testing process, Lin Jihong can undoubtedly extract the key content in the shortest time.

"Everyone, according to the omnidirectional test results of the concept model in the microwave darkroom, our basic solution can fully meet the performance requirements put forward by the aviation force... Especially in the 60-degree cone range in front, when facing the 3-12GHz frequency range, that is, the X-band, S-band and part of the C-band radar waves, the radar cross-sectional area is reduced by 2-3 orders of magnitude compared with the existing main models, effectively reducing the detectability when facing conventional radars."

"This result is basically consistent with our theoretical judgment on the characteristics of electromagnetic signals in the early stage of pre-research, that is, the canard in the same horizontal plane as the main wing will not have a significant adverse effect on the stealth performance of the front hemisphere, and combined with the cocoon structure of the DSI air inlet lip, it can more effectively shield the engine blades and reduce electromagnetic reflections at certain specific angles..."

As he spoke, he used the mouse to drag the 3D simulation image on the computer, and came to a forward perspective that was slightly looking down:

"It is here that we can clearly see that the intensity of the reflected signal near this angle has dropped abnormally compared to the surrounding area. Although it is only a very narrow range and has little impact on the overall reflection value, it still shows the correctness of our design idea."

At this point, Lin Jihong paused for a moment, then switched to another perspective:

"Also, although the radar reflection area in the left and right hemispheres and from directly above and below is inevitably larger due to the aircraft's large length, it is still slightly better than we expected, and can be further optimized through reasonable design of the fuselage structure and shielding relationship..."

"..."

As the chief designer, Yang Wei had also read most of the interim reports, but he still took careful notes following Lin Jihong's introduction.

After finishing this part, another deputy chief engineer, Kong Chengan, who was sitting opposite the latter, suddenly stopped writing, looked up and asked:
"Lao Lin, what you just said is the radar reflection situation in a static environment... What will happen if the wing surfaces, especially the fully movable vertical tail and canards, are moved?"

Because it is an internal meeting of the design institute, the format is relatively casual and there is no need to wait until the end for a unified question-and-answer session.

Lin Jihong was slightly stunned:
"This is just a conceptual model test. The wing surface of the model being tested is not movable, so we are unable to provide such detailed data for the time being..."

After about half a second, he added:
"But if the action surface changes significantly, it means that the aircraft is performing drastic maneuvers. According to the results of previous studies, this situation will definitely lead to an increase in the radar cross-sectional area. For example, in the confrontation that took place off the coast of Zhejiang and Fujian last year, it was analyzed afterwards that the most obvious signal detected by the opponent's F22 formation before its retreat occurred during the transition from level flight to climb..." "Hmm..."

Kong Chengan touched his chin, looking thoughtful.

Just when Lin Jihong felt something strange, Yang Wei interrupted:
"Old Kong, are you worried about the introduction of active control technology?"

"yes……"

Kong Chengan nodded:
"According to the wind tunnel test results, the lateral and directional stability of our solution is somewhat insufficient. If we want to ensure flight safety without increasing the number and area of ​​stabilizing surfaces, we must consider incorporating active stabilization control into the flight control system to increase the directional instability angle of attack through high-frequency feedback from the action surface."

"However, relaxing the static stability design will result in serious nonlinearity in the operation rules. Moreover, the action surface of the all-moving wing surface is the same as the stabilizer surface. The continuous opening and closing of the control surface will affect the stealth performance of the flying wing layout aircraft during cruising. This is also what we must do during the design process..."

Compared with traditional aircraft that only need to consider aerodynamics and structure during the design process, the research and development of fourth-generation fighter jets adds a dimension of electromagnetic reflection, which not only increases the difficulty on the technical level, but also changes the organization and working methods of the technical team.

Anyone who has worked on a project knows that adding even one constraint can multiply the complexity of the system.

What's more, a constraint field is now directly added.

There are hundreds of conditions.

Yang Wei raised his hand and pressed down, interrupting the other party's speech:

"This problem cannot be solved entirely by the flight control system. At present, our understanding of wing surface flow is still insufficient. Active control technology can only be used as a backup. Fundamentally, it is still necessary to ensure that the aerodynamic design itself has sufficient static stability. Therefore, the simplest method is to add an aerodynamic stabilizer at the cost of weakening the side and rear stealth performance to a certain extent...such as a ventral fin or a tail fin."

This idea instantly caused Lin Jihong to react violently.

Of course, after all, he was facing the project chief engineer, and he couldn't really quarrel with him.

So he thought for a moment, then suggested:
"Mr. Yang, the problem is that we applied an overly radical boundary layer separation control technology on the front fuselage, which caused the combination of the canard and wingtip to fail within a certain angle of attack range, and the lateral stability suddenly decreased. Once instability occurs, the usual heading control surfaces such as the vertical tail lose their efficiency because they are in the low-energy wing-body vortex wake and cannot respond in time."

"Then instead of adding an extra aerodynamic stabilizer, why can't we reduce the area of ​​the strakes between the canard and the main wing? This will not affect the stealth performance and can also reduce the probability of instability... I have also seen the previous wind tunnel test results. At present, the supersonic lift coefficient of this configuration is almost overflowing. Even if it is weakened a little, it will not affect the overall performance..."

Faced with this question, Yang Wei was silent for a moment:

"This is Party A's request..."

He also looked a little distressed:

"In terms of supersonic maneuverability, it must surpass the F22!"

(End of this chapter)