Siheyuan: I eat melons while doing scientific research

Chapter 1151: No Way on Both Sides, Put It on Your Stomach

For the comrades in the Air Force, things are much simpler to consider. Well, the comrades who come out of our troops are reliable!

As for how Gao Zhendong was able to study this thing so deeply in such a short period of time, that’s not important. Hasn’t he done enough similar things?

The leader of the Defense Work Committee was so happy that he couldn't stop smiling: "Okay, then this matter is settled..."

Before he finished speaking, the comrade from the Southwest Institute raised his hand and said, "Leader, wait a minute, Commissioner Gao hasn't finished speaking yet."

The way people address Gao Zhendong now is quite confusing. Even the "Consultant Gao" that had long been forgotten by people has been picked up again by comrades from the Emergency Management Bureau. How to address him mainly depends on which one the person thinks of at the time, but it's enough as long as you can understand who they are referring to.

The leader of the Defense Work Committee did not take it seriously even though he was interrupted by a comrade from the Southwest Institute. He hoped that there would be as many problems as possible at the Southwest Institute while Gao Zhendong was around.

"Commissioner Gao, you just mentioned a coupling distance..."

Gao Zhendong smiled and said, "That's a bit of a detail. We'll discuss it slowly when we get into the canard option. There'll be a lot to talk about then. Canards can bring the benefit of lift, but improper design can also cause the disadvantage of drag. There'll be a lot to discuss then. But I do have a suggestion for the airfoil."

The canard is also a wing. Theoretically, it can have all the wings that the main wing has, such as edge strips, leading edge flaps, trailing edge ailerons, airfoil, sweep angle...

However, Gao Zhendong was not prepared to consider the fighter jets so complicatedly. The canards of fighter jets in the world are not that complicated even after decades. There is no need to worry about the side strips, leading and trailing edges, but the coordination with the main wing side strips can be discussed.

Gao Zhendong knew that the wing strips of the 20Ji were elusive and sometimes large and sometimes small in the early verification aircraft and prototypes.

As for the coupling distance, it is also quite complicated. In theory, there are mainly two types of canards - close-coupled canards and long-coupled canards.

It should be noted that there is no "coupling" in the long-range canard. The long-range canard has only one function - aerodynamic balancing. Long-range canards are rarely used on fighters. Putting aside the discussion of performance, the reason is very simple - the fuselage is not that long.

Close-range coupling is to couple the airflow changes generated by the canard into the lift of the aircraft. The "far, medium, and near" coupling that is often mentioned later is actually a further discussion based on the close-range coupling of the canard.

As for these, Gao Zhendong was not prepared and could not discuss them with the comrades from the Southwest Institute here. This meeting was not prepared for these things. Besides, if he discussed the canard with the comrades from the Southwest Institute on this occasion, the leaders of the Defense Working Committee would probably cough their lungs out.

The comrade from the Southwest Institute also understood this truth and nodded. He did not continue the topic, but was curious about Gao Zhendong's suggestions on airfoils: "What suggestions do you have on airfoils?"

Gao Zhendong smiled and said: "It is not necessary to have a double delta wing. Since we already have canards, the benefits of the double delta wing in terms of maneuverability can be obtained through the canards. As for the benefits in terms of fuel consumption, that is incidental and can be compensated in other places."

There is no need to explain the details of the main wing's airfoil here, but the double delta wing can be ruled out first, so it is not necessary to explain it here.

Gao Zhendong has seen many fighter jets with canard layout, and almost none of them use double-triple layout. Good designs always converge.

"This..." The comrade from the Southwest Institute was a little hesitant. It was you who proposed the double-delta wing, and its advantages are obvious.

Gao Zhendong explained: "Double three has other costs, such as a certain amount of resistance. Since there are canards, it can be ignored unless necessary."

The double delta wing has a little drag that we are not afraid of, and the canard wing can also handle a little drag. If the drag of both is added together, there will be a lot of unnecessary trouble. The key is that the advantages of the double delta can be completely replaced or even better.

The comrade from the Southwest Institute nodded: "Okay, I understand." Oh, I forgot that aircraft design is a dynamic process. The canards are all moving, so why keep the double delta wings?

Seeing that they had almost finished their discussion, the leader of the Defense Work Committee prepared to summarize again: "Okay, then let's do this..."

Before he finished speaking, he saw Gao Zhendong's hand raised again: "Excuse me, leader, I have a little suggestion for plan number four."

The leader of the National Defense Work Committee laughed angrily: "Hey, do you still want me to summarize? Small suggestions? There are no small suggestions in your place!"

Having said that, looking at the expression on his face, he was genuinely happy.

What makes us even happier are the comrades from the Air Force and the Southwest Institute, as there is still hope!

After getting the nod, Gao Zhendong said to his air force comrades: "Since you want high maneuverability, then the high angle of attack capability must be very important to you, right?"

Comrades from the Air Force are pecking at the rice again, yes, yes, you are right!
The comrades at the Southwest Institute didn't know what the high angle of attack maneuverability had to do with the previous configuration, but since Commissioner Gao had said so, he must have discovered something. So just remember it. Regardless of whether what Commissioner Gao said next is applicable to this plan, it must be something valuable. Following the nod of the Air Force, Gao Zhendong put forward his own suggestion: "Then I suggest not using the air intake on the sides, but the belly. At the same time, correspondingly, the lower wing should not be used, and the lower mid-wing should be used."

Belly air intake?

The mid-wing is easy to deal with, but if you really use the belly air intake, the height of the fuselage will increase, and it will be difficult to use the low-wing layout.

The mid-wing has a better underwing space height, which is more conducive to the mounting of large-caliber payloads, and in this respect it is more suitable than the lower wing.

As for the lower monoplane proposed by Southwest, it is mainly because the Mirage 3 is a lower monoplane.

"Commissioner Gao, if we use the belly air intake, the air intake will be too low to the ground, which is not conducive to takeoff and landing at a field airport, right?" said a comrade from the Southwest Institute. They had considered a similar method, but felt that it was not as convenient as the air intake on both sides in terms of design.

Comrades in the Air Force also nodded, this is indeed a problem.

Gao Zhendong nodded: "Yes, but this problem can be alleviated to a certain extent, such as moving the landing gear backwards. However, for maneuverability, especially when our engine thrust is not very ideal, belly air intake is beneficial. It is not just as simple as good maneuverability at high angles of attack."

In fact, in a certain classification method, the belly air intake is a close relative of the F/A-18's air intake. Both are shielded air intakes, but the belly air intake uses the belly shield for pre-compression, while the F/A-18's air intake uses the wing slat above the air intake.

Comrades' view on the belly air intake is quite intuitive. With a big mouth facing the wind, the air intake will naturally be smooth at a large angle of attack. However, things in theory are not that simple.

Gao Zhendong explained: "I have considered it and have done some simple calculations. Belly air intake can use the belly to improve the quality of the intake airflow, greatly reduce the angle of attack of the local flow field entering the air inlet, and also reduce the local speed of the airflow at the air inlet, which is very beneficial for large angles of attack, but there is more to it than that."

Just by opening your mouth, you can come up with so many tricks?
For comrades who do not yet have the ability, energy and resources to carry out comprehensive research on the air intake, although Gao Zhendong's words are simple, his intention is obviously much better than the "staring method" or "I'm thinking" used by most comrades.

"Anything else?" The comrades from the Southwest Institute were very eager to learn.

"Also, there is a certain angle between the aircraft axis and the heading. That is, when the aircraft sideslips, the air intake on both sides will be affected by the aircraft body, the airflow field on the leeward side will be poor, and the air intake performance will deteriorate..."

Everyone could guess this, it was side sliding, so one side was blocked. But they couldn't have imagined Gao Zhendong's next sentence, after all, that could only be discovered through fluid mechanics experiments.

"Moreover, even if there is no sideslip, due to the influence of the flow around the fuselage, when the aircraft's Mach number increases to 2.2, the flow field unevenness of the air intake on both sides will be significantly worse than that of the belly air intake."

Huh? How did you know that? You just wrote something on a piece of paper and figured it out?

The comrades were very surprised, after all, this is not as intuitive as sidesliding.

However, no one dared to underestimate or deny Gao Zhendong's words. He just wrote and drew on paper, or even without writing or drawing, he came up with countless examples of techniques, ideas, and results that ordinary people could not even imagine.

Gao Zhendong's conclusion immediately made the comrades on the scene uneasy. In the non-side slip state at high speed, the seemingly evenly distributed air intake on both sides will also cause certain problems? This is a different matter.

After all, the Mach 2.2 he just mentioned is exactly the maximum speed indicator that has been set for this aircraft long ago.

Especially on the Air Force side, out of trust in Gao Zhendong, their original idea of ​​having air intakes on both sides began to waver.

However, Gao Zhendong himself is very sure that there are many highly maneuverable fighters that use belly air intake. As for the F-15, which has good maneuverability but is relatively less radical in aerodynamics and configuration, an important reason is that it is as powerful as a flying brick.

If we had such a good engine at this time, why would we consider so many things? Just do it.

"Comrade Zhendong, have you ever done any experiments?" The comrades in the Air Force themselves didn't believe what he said. Where could he conduct any experiments in just one night?

Gao Zhendong said confidently: "No, but I have done simulations."

In fact, no. The experiment was indeed done, but the person who did the experiment was the person who wrote the book or the person he cited.

In fact, Gao Zhendong had a lot of data and charts to prove what he said, but he really couldn't produce them. It was less than a day, so no matter how you explained it, it wouldn't make sense, even with a high-speed computer.

(End of this chapter)