Siheyuan: I eat melons while doing scientific research

Chapter 1150 Three-step Duck Wing (4k, 6k today)

Comrades expressed their opinions one by one. The advantages and disadvantages of Plans No. 3 and No. 4 were obvious at a glance, and everyone discussed the matter in a very methodical manner.

But in fact, the relationship between the three layouts, with tail, without tail, and without tail canard, is not as simple as it seems at first glance.

The main reason is that fluid mechanics is really against the will of heaven. In this era, it is a purely empirical science. Without a large number of wind tunnel or even flight tests, it is impossible to grasp the actual situation.

Not to mention now, even if it is put in decades later, the Citigroup’s superb skills will still tell everyone - this thing is really difficult to simulate.

Of course, the redefined excellence is another matter.

However, since some comrades mentioned Gao Zhendong, everyone remembered that Commissioner Gao seemed to have not spoken yet.

"Zhendong, what do you think?" The leader of the Defense Work Committee turned to look at Gao Zhendong beside him, only to see him writing and drawing on a notebook.

Hearing his name being called, Gao Zhendong raised his head and said, "Wait a moment, I'll do the math, you guys discuss first, discuss first."

After saying that, he lowered his head and continued writing and drawing on a piece of draft paper prepared for the meeting.

This draft paper must be destroyed after the meeting! The leader of the Defense Work Committee was furious.

Counting on the spot, Gao Zhendong has held so many meetings in the Defense Work Committee, which is not common.

"Okay, you do the math first, and we'll continue the discussion."

The comrades in the Air Force also realized this. It seems that Comrade Zhendong put a lot of consideration into the new aircraft plan.

Thinking of this, the comrades in the Air Force were not worried but became even more excited.

Comrade Gao Zhendong is so concerned about this, it seems that Chief Engineer Gao is preparing for a big job.

Big jobs are good, the bigger the better, and the comrades in the Air Force are very happy.

After all, starting from the modified Z-6, the Air Force has reaped a lot of benefits in terms of attack aircraft, multi-purpose fighters and other equipment.

You can calculate as long as you want. If anyone doesn’t let you calculate, we will deal with him first!

The comrades continued to express their opinions and had completely forgotten about Plans 1 and 2. Most of the comrades from the Air Force and the Southwest Institute were in favor of Plan 4, while most of the other comrades were in favor of Plan 3.

As for what Gao Zhendong is on paper?
In fact, he was just scribbling formulas and drawing diagrams on paper, all of which were taken from the book on aircraft aerodynamic design that he had gotten.

The reason for doing this is that although what he wants to say is not much, it is quite profound, and in some aspects the changes to Plans 3 and 4 are somewhat significant, so he has to lay the groundwork.

Seeing that everyone had almost finished discussing, Gao Zhendong felt that time was up, and while his comrades were speaking, he raised his hand.

The leader of the Defense Work Committee, who had been staring at him, followed him and said, "Come on, tell me, Comrade Zhendong."

I've been waiting for you for a long time.

Other comrades also looked at Gao Zhendong curiously.

"Whether it's number three or number four, I can't actually give you a conclusion right now. The key is what preference you, or the comrades who use this plane, have."

It's hard to draw a conclusion, this is very rare.

"Tendency?" Confused!

"Yes, the key is, which direction do you want this plane to go, and what is the static instability you have chosen?"

"What is the static instability?" I'm still confused!

"Yes, this is very important. We can even say that this thing determines the design of an aircraft," said Gao Zhendong.

For the comrades at the Southwest Institute, this statement is new. In fact, for them, the concept of static instability was only introduced to them after Gao Zhendong proposed this concept last time.

Compared with our aerodynamic research decades later, which was not to say invincible but at least hard to rival, our comrades now have not even touched the door, and many concepts do not exist at all. After all, in the original history, it was not until the 21s that we thoroughly understood everything about the MiG-.

Before the concept of relaxing the static stability of aircraft came about, not only us, but even the relevant personnel in other countries did not have very in-depth research on this thing, and we, who were still in our infancy, were even less clear about it.

Gao Zhendong had no choice but to introduce the concept of static stability, and then asked: "So, what is the static instability of the aircraft you chose? What is the average aerodynamic chord of the wing?"

This parameter is simple and complex to explain, but comrades who work in aerodynamics can generally understand Gao Zhendong's explanation.

Although they understand it, comrades actually have not considered it so much at all, because they do not know that this thing is so important.

The comrade from the Southwest Institute showed a bit of embarrassment on his face: "We haven't considered it yet. We originally wanted to select a plan first and then consider these detailed parameters."

Gao Zhendong smiled and said, "In principle, your idea is fine, but this parameter is like some core parameters. If it is not selected, it will be difficult to choose the layout, just like power."

"So what role does this parameter play in the selection of the solution? Chief Engineer Gao, we are really not very clear about this aspect, and we would appreciate your guidance."

Gao Zhendong nodded: "Let's put it this way. This parameter determines which solution has better overall performance. As this parameter changes, the overall performance of the horizontal tail, large delta wing, and canard wing will change."

The comrades then understood that it was no wonder that this parameter had to be determined first. If this parameter was not determined, it would mean that everything about the plan would be unknown.

Gao Zhendong added: "I have calculated that, from a purely theoretical perspective, if the static instability is below -10% to -15% of the average aerodynamic chord of the wing, the horizontal tail layout is actually better than the tailless delta wing and the large delta wing plus canard layout in terms of the trim pole curve angle. The canard layout's trim pole curve angle wants to be in the best area, and this number is -30%. There are many similar situations..."

He cited several examples and analyzed the advantages and disadvantages of various schemes from several angles under different static instabilities. "... It can be seen that when the main wing is a delta wing, if the appropriate static stability is selected, the supersonic drag of the canard layout is lower than that of the horizontal tail scheme. At the same time, the subsonic drag in this case is also slightly lower than or basically the same as that of the horizontal tail scheme..."

Gao Zhendong became happier as he spoke: "After preliminary estimation, this number is..."

"Cough! Cough cough!" The leader of the Defense Work Committee nearby coughed so hard that his lungs were about to burst.

Gao Zhendong understood the meaning of the song: "I won't talk about this number for now. Let's look at it from another angle. When only the trim pole curve is considered, the tailless layout has a lower takeoff gross weight than the horizontal tail and canard layouts under the three combat performance requirements of general, desired and maximum under the current technical environment, due to its low zero-lift drag and light structural weight. It has a clear advantage in terms of takeoff gross weight."

"This is why the Mirage 3 has good parameters. If only certain aspects are considered, its tailless delta wing layout has the lowest takeoff weight."

Other comrades might be a little confused, but at least the comrades from the Southwest Institute were fascinated by what they heard. They learned a lot of design experience of tailless delta wings from the Gauls, but even the Gauls themselves did not quite understand the knowledge of comparing multiple plans, especially the canard part.

As for how Chief Engineer Gao knew it, it’s as obvious as the lice on a bald man’s head. He just counted it.

Comrade Gao Zhendong worked very hard as he spent the whole night and half a morning calculating.

The Air Force was confused. Although Gao Zhendong had only talked about the most basic conclusions, they still did not fully understand. The required professional background knowledge was quite a lot, but they only cared about one thing.

"Comrade Zhendong, what do you think is the appropriate static instability? In other words, according to our idea, which solution should we use?"

Gao Zhendong smiled and said, "According to my estimation, your requirements for the new fighter are both high speed performance and high maneuverability, right?"

The comrades in the Air Force nodded their heads in agreement: "Yes, yes, that's the idea! Comrade Zhendong, you understand our operational needs."

In fact, at the beginning, what they valued most was high-altitude and high-speed performance. After all, this was the mainstream air combat performance demand in the 60s. Whether it was the Americans or the Russians, the air superiority fighters at that time were desperately moving in this direction.

But after listening to Comrade Zhendong's words, it seems that he can still take care of both? Then he should quickly climb up the pole, right?

Gao Zhendong laughed loudly while listening to their words. If they wanted this and that, then there was nothing we couldn't guess.

"Then try to relax the static stability and choose the duck style..."

In the absence of insufficient power and vector engines, the canard layout is the most basic configuration that is easiest to achieve to meet the needs of the Air Force under our current technical conditions.

"Ah, that's Plan No. 4..." The comrades from the Air Force and the Southwest Institute were very happy. As for the difficulty, that was a matter for later.

"But..." Gao Zhendong left a tail to his previous words.

"But what?" The comrade from the Southwest Institute immediately picked up the pen. The "but" and "however" in this context are undoubtedly extremely important.

"But your canard is not good enough. If you want to make it, let's make it bigger. Fixed canard is meaningless. We use fully movable canard, and the coupling distance of the canard needs to be carefully considered!" Gao Zhendong made a big move as soon as he opened his mouth. What's the point of making a small move? If you want to make it, make it big!
"Fully moving canard? Coupling distance?" These are undoubtedly like a mystery to those comrades who have only just heard about the canard layout and incorporated it into the plan, and have not even started to conduct specific research.

The leader of the Defense Work Committee covered his forehead with his hands. Well, this kid's habit of doing something big from time to time is back. One look at the expression of the Southwest Institute showed that this thing was absolutely new, brand new, and undisputedly new!

As for things like technical difficulty and risks, when did Gao Zhendong ever take these things into consideration when he was taking big steps?
The other comrades looked confused, but the Air Force was excited. They knew that Comrade Gao Zhendong had hidden something good! The newer the better.

"Yes! Let the canards move and actively participate in the change of aerodynamic configuration and even the control of the aircraft. This will actively and most appropriately change the aerodynamic state of the aircraft under various conditions, improve various flight qualities, and further enhance the maneuverability and agility of the aircraft."

The maneuverability of a tailless delta wing cannot be considered bad, after all, maneuverability also includes acceleration and climbing, but its agility is relatively average.

The full-moving canard allows the canard to move, which not only improves agility, but also has the effect of increasing lift under the right conditions.

Gao Zhendong's words made the comrades at the Southwest Institute both surprised and uneasy.

What was surprising was that they could actually take the existing solution to the next level. What was disturbing was that in their opinion, canards were already difficult, and fully movable canards? It was mind-boggling!

Even they themselves did not dare to rush up directly: "Chief Engineer Gao, isn't a fully movable canard a bit too difficult? We don't even have basic research on canards. Is a fully movable wing..."

Gao Zhendong waved his hand carelessly: "Don't worry, we can proceed in three steps to gradually improve the flight control. The first step is to keep the canard still and only participate in the aerodynamics under static conditions. In this step, it is a fixed canard."

Hey, this is a good suggestion, use the canard as a fixed one!
"In the second step, we studied several sets of preset positioning solutions for the canards in specific and most demanding states. This is considered semi-movable..."

Well, we study some of the most versatile prefabricated solutions to fully utilize the advantages of movable canards when they are urgently needed or have the widest range of uses.

"The third step is to fully activate the canards and fully, comprehensively and fully participate in the flight and maneuvering of the aircraft."

This is the ultimate goal.

The leaders of the Defense Work Committee were relieved. As expected, although Comrade Gao Zhendong was radical at times, he was never impulsive. He had a complete set of step-by-step plans, and he would definitely be able to support himself.

The air force nodded frequently, knowing that Comrade Zhendong was reliable.

Other comrades were also relieved. This plan was good and took into account performance, risks and potential.

The comrades at the Southwest Institute were very happy. They were not afraid at all to do this!
Gao Zhendong's next words gave everyone the final reassurance: "I have studied the duck wing carefully these past two days, and after some calculations, I have some experience. We can exchange ideas when the time comes."

Comrade Zhendong usually takes personal responsibility when taking big steps.

The comrades were relieved. Those who knew Gao Zhendong knew that since he dared to say so, the matter would not be too bad. At least there would be no problem in being a fixed canard operator.

The only thing that makes people feel a little annoyed is the sentence "these two days". Two days is bullshit. It only takes one night and half a morning, and he can actually research so much and so deeply?

There is no comparison, really no comparison. The comrades at the Southwest Institute all shook their heads inwardly. Eh? This is our own expert? That's fine.

(End of this chapter)