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

Chapter 14 This can no longer be described by the word academic master.
Chang Haonan did not delay for too long. After Liu Hongbo turned around to maintain order, he began to explain:
"In view of the shortcomings of the J-7, the main fighter of the People's Air Force, which has poor all-weather combat capabilities and does not have beyond-visual-range combat capabilities, our team changed the nose inlet of the original model to a mandibular inlet, leaving the nose The space can install a radar with a diameter of no more than 560mm, and at the same time, the flight performance of the aircraft is equivalent to or better than that of the prototype."

"In addition, with the rapid development of supersonic aircraft, the boundaries that separate the aircraft from the power plant, internal flow and external flow have been broken. Therefore, during the design process, we adopted a chin-type inlet/conical front body integrated design The scheme, verified by computer simulation, shows that the inlet/conical front body/engine matches well, reflecting the advantages brought by the integrated design. The design ideas are now explained as follows. The calculation process is located on pages 14-15 of the design description. Calculation Fortran language programming and Fluent software were used in the process..."

"The performance analysis of the integrated model of the inlet/cone front body is completely performed by computer. The simulation ideas and methods are as follows..."

"In order to test the reliability of the calculation method used, this article conducts numerical verification using the double ellipsoid model whose detailed performance data is given on pages 213-217 of the textbook. The results are shown in the figure."

"Under different incoming flow Mach numbers and different incoming flow angles of attack, the results calculated in this article are in good agreement with the experimental data, which shows the credibility of the calculation method used in this article..."

The judges just listened at first, but soon they realized that the design was very complete and well-thought out, and was by no means a half-finished product. So they began to read the design instructions in front of them, and discussed in low voices from time to time.

When Chang Haonan started to talk about the specific design process, the four of them even opened their notebooks and started recording quickly.

Of course, the four professors are all involved in CFD simulation. They do not have to copy everything Chang Haonan said like Yao Mengna. They only need to write down some interesting ideas.

But for other students in the back of the classroom, this scene was already shocking.

On the stage, an undergraduate student was talking nonstop.

In the audience, the four judges were... taking notes?

As for the specific content of what Chang Haonan said, not many people care about it.

I don't understand anyway.

Huang Zhiqiang, who was full of confidence in himself just now, was even more stunned when he saw this scene - obviously the reason why the design instructions were only half as thick as those of their group was because there were a large number of steps that were not, or did not need to be, reflected on paper. .

As for the three-dimensional shape design of the inlet entrance that the design manual in his hand said "needs to rely on experience" to complete, Chang Haonan directly showed an exquisitely drawn half-mold schematic diagram, using only two sentences to convince several judges He nodded repeatedly.

Just because he couldn't understand didn't mean that the teachers couldn't understand. Chang Haonan's ideas were obviously recognized.

"After the design was completed, we compared the aerodynamic performance before and after the improvement. At a speed of Mach 1.5, the angle of attack was in the range of 0 to +10° or the sideslip angle was in the range of 0 to 6°. The total airway pressure recovery coefficient reached above 0.950."

"The speed is Mach 0.8, the total pressure recovery coefficient within the same angle of attack or sideslip angle range reaches above 0.968, and within the flow coefficient range that matches the engine, the maximum total pressure distortion index does not exceed 0.14."

“新的进气道设计在亚音速下的性能与原始设计相比提升约3%到8%不等，1-2倍音速之间的性能提升则超过10%。”

"Compared with the MiG 21MF inlet design that enlarges the intake nose cone and installs a radar, the performance in the full speed range is improved by at least 23%, and the conical front body can accommodate a radar with a maximum caliber of 560mm. According to Existing models are estimated to be enough to lock a fighter-sized target at a distance of about 30-40 kilometers."

Although the previous content is obscure and difficult to understand, the students here can still understand the data indicators mentioned at the end by Chang Haonan.

Therefore, the back of the classroom, which had been silent when the design process was discussed, quickly started to boil again.

In the mid-90s, beyond visual range combat was the most urgent issue for the Air Force. It can be said that whether there is a beyond visual range combat capability is the difference between 0 and 1.

Because of this, for a long time, "pointed aircraft" that can be equipped with large-caliber radars have been synonymous with advanced. Only a small number of J-8Bs and Su-27s have this feature.But today, they actually saw an improved J-7 that also had the same characteristics and could be installed with radar!
Don’t look at the figure of 30-40 kilometers, which seems small. You must know that the AIM90F air-to-air missile, the main force of the US military in the 7s, has a maximum range of only 40 kilometers in a head-on attack. On this basis, the Aspad and Aspaid purchased by our country from Italy The imitation Thunderbolt 11 has a range of only 30 kilometers, so this 560mm nose is enough for now.

Not to mention that on this basis, the flight performance of the aircraft has not been reduced, but has been improved!

“这个歼7改进型如果搭配霹雳11的话，那就已经和F16差不多了啊！F16带AIM7也就能打个30多公里的样子。”大多数学航空的人对于空军还是有一些了解的
"Well, there may still be a certain gap in terms of range, after all, the size of the aircraft." The other person seemed to be more rational, but there was obviously excitement in his tone.

"Hey, what's the problem with short range? We don't bully others like the Yankees. Let me see, if we can have 200 at the beginning of the year, no, we can have 100 of these improved J-7s. Those two The aircraft carrier certainly wouldn’t dare to be so rampant!”

This sentence instantly gained unanimous approval from the people around him.

Although our country's aviation industry is still relatively backward, the supply of J-7 can still be opened up. However, the current model of J-7 has lagged behind when it was manufactured, so it can only maintain a small amount of production.

For a time, although everyone's views were not unified, almost everyone in the classroom began to discuss the aircraft's performance, cost, manufacturing difficulty and even the prospects of equipping the troops.

In fact, not only the students behind, but also several judges and teachers began to consider whether this improved model really has the possibility of being implemented?
"Xiao Chang, although your design still has some room for improvement, personally speaking, I have nothing to ask. If you let me take charge, I will definitely not be able to come up with a better plan than this."

Professor Li Guang, the oldest of the four judges, took off his reading glasses and said, looking at Chang Haonan with relief in his eyes: "So I want to ask, do you think there are any problems that need to be solved in the manufacturing of this aircraft? What?"

This is almost impossible to give a higher evaluation. You must know that this course only requires aerodynamic design, and manufacturing issues are not included in the assessment scope.

Chang Haonan had already been prepared for this.

"Hello Professor Li, we have considered this issue at the beginning of the design. 60% of the parts of this improved model can be used in common with the original model. The performance requirements of the new parts generally do not exceed the level of the MiG 21MF. However, considering the weight of the radar, in order to maintain aerodynamic balance, some composite materials need to be applied to the air inlet and radome to reduce weight, accounting for about 2% of the total material of the aircraft body."

Composite materials with a dosage of 2% are not a new thing for the Chinese aviation industry. They have already had experience with the J-7M, J-8B and J-7.

Therefore, this answer is basically equivalent to "There is no problem that needs to be solved." However, it seems not modest enough to say so directly, so I found a problem that is not a problem.

"I think if conditions permit, can we build a scale model and go to Mianyang to try it in the wind tunnel?"

Liu Hongbo's voice was not very loud, and he said it to three other teachers, but someone still heard what he said.

The wind tunnel in Mianyang is not just a small experiment in a school laboratory. Going there to test, even if it is just a scale model, means that the plan really has the potential to take root.

You know, this is just a junior year course design!

The already silent discussion started again, but this time, more people's attention shifted to Chang Haonan.

Obviously, the word "student master" is no longer enough to describe such a person.

(End of this chapter)