Chapter 34 Key Decision [Please read]

Early the next morning, Du Yishan took the first flight of the day to Haojing, and then met Director Zhou Yonghang and Chief Engineer Yi Yuanhe at the 603 Institute.

The former had already called two people last night and asked them to set aside a whole morning.

After the meeting, Du Yishan took out a floppy disk containing explanatory materials that he had compiled overnight.

Everyone is engaged in technology, so there is no need to waste words. Zhou Yonghang and Yi Yuanhe quickly realized the value of the contents of the floppy disk.

Scientific research is nothing more than discovering and solving problems.

But when it comes to actually doing something, it's often a mess, and it's not easy to find a place to start from the chaos.

Zhou Yonghang and Yi Yuanhe are both well-informed old engineers, but after reading this idea of ​​​​solving the problem, they still feel unreal.

Generally speaking, the development of engineering models is relatively gradual. New methods that have just been born are always immature. When solving practical problems, they often need to be supplemented by old methods or experience.

But the set of things displayed on the screen in front of them started from multiple directions at the same time, and finally converged on the key issue of wing flutter analysis.

In this process, a series of secondary engineering problems including incremental finite element analysis, aero-servo-elastic modeling and model predictive control were simultaneously solved.

It's as if this method has always existed, and has even developed and matured over ten or twenty years, but they were ignorant and had never heard of it before.

It's a bit like the feeling when I first came into contact with calculus.

"It has to be Academician Du."

Zhou Yonghang leaned back on the large seat back and said in an admiring tone:

"If I hadn't known that this was a new method you created, I might have thought..."

Before he finished speaking, he was interrupted by Du Yishan: "I didn't create this. At Du's age, if he wants to come up with something new in terms of methodology, I'm afraid he won't be able to do it."

"That is……"

Yi Yuanhe next to him looked curious.

"He is one of my students. The waves behind the Yangtze River push the waves ahead."

Du Yishan hesitated for a moment, but ultimately did not reveal Chang Haonan's identity as an undergraduate.

He was afraid of scaring two old colleagues.

It is not too late to wait until this method is verified.

"Lao Du, if this engineering model is verified, I'm afraid..."

Zhou Yonghang looked at the computer screen in front of him and hesitated for a moment, but finally continued:

"I'm afraid it can be regarded as the most outstanding achievement of our Chinese aviation industry in the field of aircraft design methods."

Coming from the mouth of the director of Institute 603, these words can naturally be regarded as extremely high praise.

"That's why I came to you."

Du Yishan didn't make any meanderings, put the tea cup in his hand on the table in front of him, and got straight to the point:

"Do you dare to verify this engineering model on the Yun-7-200A project?"

The two people sitting opposite looked at each other.

This question is difficult to answer.

From the derivation method and simulation calculation process, they found no problems.

But the starting point of thinking about the problem between the two and Du Yishan was different.

Especially Yi Yuanhe.

This is determined by the different positions of several people.

Starting from the 941 (Manned Spaceflight) Project, China’s engineering projects have gradually established a main tone:

The chief engineer makes the decision and the chief engineer is responsible.

The final decision on any matters related to Yun 7-200A is made by chief engineer Yi Yuanhe.

Correspondingly, if something goes wrong after this engineering model created by Chang Haonan and recommended by Du Yishan is applied to aircraft design, it is not them who need to bear direct responsibility, but Yi Yuanhe.

That is, the unity of authority and responsibility.

If Du Yishan was placed in that position, he would definitely have the same idea.

Yi Yuanhe lit a cigarette, put the filter tip into his mouth and took a long puff.

If this model only involves nonlinear flutter analysis, there is actually nothing to worry about.

First blow a wind tunnel to verify the accuracy of the model, and then conduct a test flight if it passes the test.

The risk will always be smaller.

But this flutter is actively suppressed...

It has only been more than ten years since the concept was first proposed in the West.

It hasn't even really been used in aircraft design yet.

Since it involves the action of the pneumatic control surface, it is difficult to verify it through a blow tunnel.

Because the scaled-down wind tunnel model simply does not have an aerodynamic steering surface, even if it is made, it cannot be controlled according to the control rate written by Chang Haonan.

As for the full-size model…

The wingspan of the Y-7 aircraft is 29 meters, and after replacing the new wings, it is nearly 35 meters.

I really can't find a wind tunnel of this size.

So it has to be tested directly after theoretical verification.

The risk is huge.

You must know that there is only one verification aircraft currently undergoing airworthiness testing.

In addition to being responsible for the verification of this project, this single aircraft is actually a verification of CCAR25, China’s new airworthiness regulations that are in line with international standards.

If something goes wrong, it will be a small matter for him to be infamy for thousands of years, but it will be a big deal for him to delay the development of the entire Chinese civil aviation and aviation industry.

Yi Yuanhe lit a second cigarette.

Du Yishan, who had also been a chief engineer, knew how much pressure there was in this situation, so he just stared at the flickering cigarette butts through the swirling smoke, and did not rush to urge him.

More importantly, as he said in the lab yesterday.

Since the 603 Institute reluctantly launched this project, it shows that there are expectations and pursuits for this new passenger aircraft.

It would be fine if the results given by Du Yishan were the same as Huo Gent's.

But now that this opportunity is right in front of them, they cannot turn a blind eye.

……

The silence between the three people lasted for almost half an hour.

Until Yi Yuanhe finished smoking the sixth cigarette, which was also the last cigarette in the cigarette box.

"From my personal point of view, of course I hope to use more advanced designs, otherwise it will be difficult for new aircraft to open up the market. If we just buy a few of them to follow the lead of domestic airlines, it is not the result we want. .”

Perhaps because of smoking too much in a short period of time, Yi Yuanhe's voice was a little hoarse:

"But we still have to be scientific and not act recklessly."

After finishing speaking, Yi Yuanhe put out his cigarette butt in the ashtray, stood up and walked to the window, looking at the track outside:

"We will proceed in two steps. First, we will improve the current No. 01 demonstration aircraft to verify the effect of active flutter suppression. After passing the test, we will replace it with a new wing and conduct a full-state test flight."

As the chief engineer, he cannot make radical improvements to an aircraft that is already in a test flight state by just patting his head in the absence of verification.

Being able to make this decision was already under a lot of pressure and risk.

After all, there is often only a thin layer of window paper between being bold and promising and being blind and reckless.

Who can be sure that the score will be accurate?