Chapter 188 MiG-21 Modification that Even Mom Can’t Recognize (Two-in-One)

Since we had to work the next day, the reception banquet did not last until too late, and we drank very restrainedly.

Most people still maintained a very clear consciousness when the show ended, such as Sun Huizhong, deputy chief designer of the 648 Institute, who flew from Zhucheng to Chengcheng just yesterday afternoon.

He didn't speak the whole time just now, just quietly listening to Chang Haonan's explanations to other people's questions.

Although he had heard about this young genius's deeds from many channels, Sun Huizhong felt that he still had to see it with his own eyes.

So now, the only chief engineer of the 648 Institute only has admiration in his heart.

"Regular worker!"

After leaving the guest house, Sun Huizhong called Chang Haonan from behind and followed him quickly:

Chang Haonan turned around and saw a man with half-white hair standing behind him.

"May I ask you are……"

Although it sounds like he has done a lot, it has only been half a year since he traveled through time, and he didn't have time to interact with too many people.

As an ordinary military engineer in his previous life, he also had limited connections, so except for a few well-known bosses, most of the faces were unfamiliar.

"Sun Huizhong, from City Building 648."

The two shook hands under the dim streetlight.

After taking a closer look, Chang Haonan discovered that the other person did not seem to be particularly old. He was probably in his early thirties. The reason why he grew old early was probably due to congenital reasons or too much pressure.

"Chang Gong, I would like to ask some more questions related to hair matching."

After all, it was already very late, and Sun Huizhong lived in the guest house and was not going in the same direction as the dormitory area, so he didn't make any detours and directly explained his purpose.

Chang Haonan would naturally not refuse this kind of thing:

"Please say."

"What we want to do is develop a two-seat aircraft based on the J-7F."

Sun Huizhong does not shy away from the idea of ​​borrowing ideas from his brother units. After all, the design team of Institute 648 only has a three-digit number of people, and its experience and level are hard to describe. In this case, there is no shame in choosing to copy the homework:

"But I heard from comrades here in Rongcheng that the J-7F's air inlet and front fuselage are integrated designs completed by you. Modifications to the fuselage will seriously affect the air intake efficiency, so I would like to ask, what do you think? How feasible is this plan?”

"It is indeed the case. The high air intake efficiency and stability of the J-7F are based on the primary compression of the incoming flow by the nose part. If you want to convert it to a two-seater, you will inevitably have to perform some modifications to the front fuselage. A major change would almost require overturning the entire design.”

Converting a single-seater to a two-seater may seem simple, but the operation requires a lot of work.

For some relatively small aircraft, one more pilot will have a significant impact, and the more sophisticated the aircraft's aerodynamic design, the smaller the operating space left for such changes.

The J-7F occupied both sides, which was particularly troublesome.

So after a little thought, Chang Haonan quickly gave his opinion, even though it was a basin of cold water:

"When I designed this model, I just wanted to give the J-7 a true beyond-visual-range combat capability. I didn't think about letting it take on more complex functions, so I didn't leave much margin. If it were changed to a two-seater ...I personally am not optimistic about it.”

At that time, he had just traveled through time, and he just wanted to quickly create a short and quick project to attract the teacher's attention, so that he could quickly participate in a specific model project.

In fact, Chang Haonan still hasn't figured out how he crossed the level of Professor Liu Hongbo and directly attracted Du Yishan's attention.

All in all, the final result was much better than expected.

"So that's it..."

Sun Huizhong, who was standing opposite, lowered his head slightly and showed a somewhat regretful expression:

"We originally planned to further improve the J-7, and are currently doing pre-research work on wing selection and air inlet matching. After coming into contact with the J-7F project, we originally thought we could have a better reference. Unfortunately, …”

When the other party said this, Chang Haonan suddenly remembered the conversation he had with the two pilots of the 25th Hainan Airlines Regiment at the J-8C delivery ceremony.

They said that the army currently lacks a useful advanced training aircraft.

To solve this problem, designing a new advanced trainer aircraft from scratch is of course the best way, but currently there is no such solution in terms of funding or technology.

Among other things, two small-thrust or one medium-thrust turbofan engines cannot be produced.

Besides, we don’t have that much money right now.

However, it is still feasible to use the redundant digital fly-by-wire technology of the J-8IIACT, combined with the medium-thrust, excellent-performance turbojet 14, to develop a model based on the J-7.

The final product of this idea in later generations was Coach 9, which happened to be the product of 648 Institute.

And Chang Haonan is fully capable of making it born in advance, and...

Become more perfect!

So he changed the subject and said to Sun Huizhong, who was already preparing to say goodbye:

"Since you have such an idea, you might as well be more bold."

After hearing these words, the latter's eyes suddenly lit up, and he raised his head and looked at Chang Haonan:

"You also think we need a new advanced trainer aircraft?"

Although the plan based on the J-7F technology has been rejected, Sun Huizhong is very happy to get recognition of the idea of ​​​​this training aircraft.

You must know that the conversion rate of pre-research results is actually very low. Sometimes out of 10 pre-research plans, only two or three will eventually become formal projects that can be carried out, and even fewer may eventually achieve positive results.

The two pre-research reports they submitted before were rejected due to lack of depth.

Therefore, Institute 648 also has internal concerns about the plan for this new advanced trainer aircraft——

Bite the bullet and continue will require more investment, and no one can guarantee that the army will definitely want it. This is a risk for them with a small family and a small business.

Even Sun Huizhong, who originally proposed the idea, didn't have much confidence.

You must know that although he holds the title of deputy chief designer of the 648 Institute, this is entirely because there is really no talent in the institute, so he is replaced by a person who is less than 30 years old and has not led any model design.

If you are young and have no successful experience, you will naturally lack confidence.

So when he heard Chang Haonan express his support, Sun Huizhong was quite excited.

Although the former is younger, judging from what happened at the dinner just now, he definitely has real talent and knowledge, and he played a very important role in the 83rd Project. His statement is definitely weighty.

"Of course, JJ7 was created by you, and you should be very aware of the flaws."

Chang Haonan nodded and did not show mercy just because the person in front of him came from No. 648:

"The low-speed performance and rear-seat visibility are so poor that instructors even need to make their own periscopes to observe the situation ahead during takeoff and landing, and the potential is not enough. It is barely enough to train J-7 and old J-8 pilots, but our Air Force is making great strides." We have entered the third-generation machine era, so this model will definitely not be able to play a leading role for a long time."

In fact, the JJ-7 model was supposed to only play a transitional role, and it would be gradually replaced with new training aircraft after entering the new century.

But like many other equipment in this era, it transitioned to become the main equipment.

Due to various reasons, the planned new training aircraft never arrived. In the end, the JJ-7, as an essentially basic second-generation aircraft, was produced until 2017...

"Oh...that's so right."

Sun Huizhong sighed softly:

"With your words, we can feel more at ease as we continue to carry out preliminary research."

"You just said that you are currently working on wing selection and inlet matching. What is the specific progress?"

Coach 9 is not a star model. Chang Haonan only knows that it was not officially put into service until 2011 in the original timeline, and does not know much about the research and development process.

"At present, it has been initially determined to use a double delta wing similar to that of the J-7E. As for the air inlet... it has not been finalized yet. I originally wanted to refer to the mandibular air inlet, but you just said that it is not feasible, so... maybe we will have to do it again. Think about it.”

Sun Huizhong was a little embarrassed when he said this. After all, it sounds like this aircraft is borrowing from the model of his brother unit from head to toe...

Chang Haonan didn't care about this. What he was thinking about now was how to tell the other party the design plan in his mind.

Not just let 648 Institute simply copy the answers.

It is better to teach them to fish than to teach them to fish. It is best to let them gain experience from it.

Moreover, he only has a preliminary concept of Coach 9 now. More detailed information can only be obtained through calculation. In short, there is definitely no way to come up with the design plan tonight.

So Chang Haonan thought about the sentence:

"Actually, when I was designing the J-7F, I also considered another option. However, the changes compared to the J-7 were too big and there was no way to directly upgrade from the old aircraft, so the design work was only carried out a little. .”

"If you are so willing, after I finish processing the changes to match the new engine of the J-7F, I can work with you to improve the plan..."

This was a complete surprise for Sun Huizhong.

So before Chang Haonan finished speaking, he quickly agreed:

"Of course, I can apply to the institute to transfer some key members from the design team."

Sun Huizhong never thought about letting the other party go to the 648 Institute from the beginning.

On the one hand, anyone with a discerning eye can see that Chang Haonan's visit to 611 this time is just a side trip to engage in the J-7F, and participating in the No. 10 Project is probably a serious matter. This new training aircraft is not an important project, and it is impossible to take up too much time and energy on it. .

On the other hand, among the cities corresponding to the major designs of the aviation industry, Shengjing, Haojing and Rongcheng are definitely the best. Ice City, Porcelain Capital and Hongdu are also okay, but the geographical conditions for building the city are really good. It's worse.

"Then let's do this for now. We can talk after the matter on 7F is over."

Chang Haonan nodded as he spoke:

"In addition, those who are transferred must at least master some basics of digital design, so the efficiency will be much higher."

"No problem, I'll call tomorrow."

At this time, Sun Huizhong already had excitement on his face:

"Thank you so much, Chang Gong!"

…

The next day, Chang Haonan started working non-stop.

Random events, in the first half year, the team led by Lu Yuying was not idle, and had almost completed the design of parts other than the inlet and nose.

For him, he has actually gone through the J-7F design process once. Now replacing a new engine is nothing more than taking the entire project team to go through the process again.

Back then, three real undergraduate students were able to complete the preliminary design within three weeks, but now it is no longer a problem.

Moreover, the equipment level of the 611 computing center is no worse than that of Shengjing.

In short, with the cooperation of Chang Haonan and the project team, the complete design plan of the J-7F was successfully produced after half a month.

Compared with the original version of the design, in addition to narrowing and shortening the air inlet to make the aircraft look more coordinated, the cockpit windshield was also changed to an arc type based on Yao Mengna's experience when improving the J-8C, which greatly improved It improves the pilot's field of vision, and adds a set of 140-liter fuel tanks at the root of the vertical tail, which improves the range even more than nothing...

As for the remaining work, naturally it was to send the drawings to Factory 132 and let them build two prototypes.

A J-7F1 upgraded from the J-7B, and a newly manufactured J-7F2.

But now it’s the end of January. No matter how efficient it is, the first flight will have to wait until after the year.

As for the rest of the year, it will naturally be left to Sun Huizhong and the 648 Institute.

They have been waiting here in Chengdu for half a month, and have also participated in the improvement work of the J-7F, which can be regarded as accumulating some experience.

…

Computing center, inside the server room.

Sun Huizhong placed a pile of information on the table in front of him:

"Chang Gong, this is the main result of our current pre-research, and it's all here."

Several comrades from Institute 648 gathered around the square table and looked expectantly at Chang Haonan, who was focusing on the drawings in front of him.

In the process of improving the J-7F, they finally experienced what work efficiency is.

So now I basically have unlimited confidence in the latter.

After a long while, Chang Haonan raised his head again:

"Since it is a training aircraft, it is not suitable to use a single inlet design."

He picked up a red and blue pencil, took out a piece of paper from the side, and drew a front view of an airplane on it:

“Whether it is the nose, belly or lower jaw, the single air inlet must be arranged on the axis of the fuselage, occupying the height space. This makes it difficult to arrange a rear cockpit with a height difference, so the air intake on both sides must be selected. "

"Considering the structural characteristics of the J-7 itself, it is not appropriate to make too many changes to the rear fuselage, so basically we can only consider the design of the under-costal air inlet."

"In addition, as for the wings, there is nothing wrong with the choice of double delta wings, but the design of the J-7E is still too rough now."

Chang Haonan put down his pencil and motioned for everyone to come to the workstation:

"There are two types of double delta wing plane shapes: one has fixed front and rear wing sweep angles, which is the straight-sided double delta wing on the J-7E. The other type has a fixed front wing sweep angle. The angle will gradually increase from a certain angle until it is 90° parallel to the fuselage. In this case, the essence of the front wing is close to an extremely large-area side wing, and the shape of the rear wing will also become The swept wings with a smaller angle are like those of an F18 fighter jet.”

He called up the 3D model of the wing that he had made a few days ago while waiting for the calculation results, and then continued:

"From a styling perspective, the distance between the front wing vortex and the rear wing vortex of the latter scheme will be larger. At a larger angle of attack, the position of the vortex rupture point has been advanced to the front wing surface. In the middle, the separated flow formed after the spiral vortex breaks is re-formed into a fairly compact vortex structure due to the influence of the increasing local sweep angle."

"Such a separated vortex structure distribution allows the latter solution to still generate considerable vortex lift after the front wing vortex breaks. In other words, the aircraft's stall angle of attack and lift coefficient will increase, and the maneuverability at large angles of attack will be reduced. , especially the rolling maneuverability is better.”

"As a price, the resistance of this solution is much greater than the first solution. It should be difficult for the aircraft's maximum speed to exceed 1.5 times the speed of sound."

At this point, Chang Haonan finally put together several preliminary parts to form the shape of an airplane:

"But for a training aircraft, as long as it allows students to experience supersonic flight, the maximum speed is not the core performance. Using it in exchange for a comprehensive improvement in high angle of attack performance is definitely a sure-profit deal. ."

"Of course, more detailed numerical calculations have not yet begun. The specific design plan and the extent to which it can ultimately be optimized are not yet known, so this is also our main task in the following period."

But most of the people around him didn't hear these last two sentences.

Because everyone’s attention has been attracted by the aircraft model on the screen——

Although it has not yet been designed in detail, it is very rough and uncoordinated.

but……

Two-rib air intakes, swept wings with large edges, a huge cockpit with good visibility due to freeing up space, and even a nose that can fit a small radar...

If we look at the J-7F, we can still see a little bit of the original model.

So even if the designers of the MiG Design Bureau were brought over to see the aircraft in front of them, they would never recognize it as an improved version of the MiG-21!