Chapter 982: It Turns Out that Mr. Chang Is so Happy Every Day?

In addition to Liu Hongbo and Ed Steiner, other people in the computer room naturally took advantage of this time to communicate quietly.

In French, of course.

"I remember that the wing design was entrusted to the Chinese people at the end of October last year, and it has only been about four months in total..."

A relatively young technician looked at the slowly moving progress bar on the computer screen and said to several colleagues around him:

"At that time, the starting point for the optimization of our critical speed was around Mach number 0.8. In such a short period of time... could it really be optimized to the 0.95 level required by the design?"

Several people were standing in a relatively remote place, and they could see that the Chinese man didn't seem to understand French, so they didn't worry about their words being overheard.

"If we just talk about critical speed, I wouldn't be too surprised..."

The next person who spoke was another middle-aged female engineer sitting on the chair:

"In fact, there are many mature technical means that can increase the critical speed to a level close to Mach 1.0, but that is only the most superficial problem in wing design..."

In fact, since the concept of supercritical wings was first proposed in the late 1960s, the lift coefficient of straight wings at medium and high speeds has not been a problem.

This technology can greatly delay the point where the drag divergence occurs on the upper and lower surfaces of the wing, and increase the relative thickness of the wing by 30% to 50% at the same drag divergence Mach number, allowing aircraft designers to design designs without changing the total weight. A wing with a larger aspect ratio.

That is, thinner.

As early as the early 1970s, Airbus had already adopted supercritical airfoils when designing the A300.

By the beginning of the 21st century, in the field of pure aerodynamic lift design, it was indeed no longer a new technology.

Therefore, everyone nodded.

"but……"

The female engineer changed the subject:

"My main concern is that these Chinese people only have experience in numerical calculations, but lack the accumulation of wind tunnel or test flight data. On the surface, everything looks normal, but once they actually enter the testing stage, troubles will come one after another... "

Obviously, not everyone initially agreed with leaving the wing design task to China.

"If you are referring to the wing flutter problem, then I don't think it will be..."

A bald old man who had just been staring at the computer screen also turned around:

"Probably... uh... it should be about six years ago. At that time, the Chinese people designed a regional passenger aircraft with Finmeccanica Group. Of course, they were jointly designed, but there was basically no Italian participation in the hardware part."

"In my impression, the airfoil design of that aircraft is quite good and it is very competitive among aircraft of the same level."

"You have always worked at the headquarters, so you may not have much impression, but I have flown it once before on a business trip to Egypt. For a propeller aircraft, the noise and vibration levels are first-rate..."

It is not difficult to tell from what he said that he has a high opinion of the MA60.

"I do know that model, it seems to be called MA60?"

The female engineer just replied:

"I heard that it has indeed had a big impact on the market of ATR72 and Dash8. However, even at the maximum speed of a turboprop airliner, it is impossible to exceed Mach 0.5. The flutter problem in that speed range is completely different from that in the transonic speed range... "

"this……"

A well-founded refutation left the other party speechless:

"That's true..."

"..."

While everyone was chatting separately, the data in the first batch of hard drives had been transferred. While replacing the second batch, the technicians also opened the transferred project documents at Ed Steiner's request.

For a moment, everyone, whether they were doubtful or determined, focused their attention on the computer screen located in the center of the computer room.

After a slightly long loading time, the PDF document was loaded.

Ed Steiner quickly skipped the previous meaningless content such as project background, and prepared to scroll directly to the key part——

Liu Hongbo may not understand French, but he can understand it.

Although he had been chatting with the former just now, Ed Steiner did not ignore the whispers of the people in the corner.

As the project leader who made the final decision to hand over the wing design to Huaxia Design, he was quite confident.

Now I feel a little guilty.

If, as the female engineer said, there was a major problem with the wing during the test, it would be an absolutely devastating blow to the project progress.

And it's pretty much the same for him.

Fortunately, at this time, Liu Hongbo next to him looked at Ed Steiner, whose anxiety was almost written on his face, and extended a helping hand in time:

"You can just turn to page 377."

"What?"

Ed Steiner subconsciously stopped moving his hands.

"Page 377 and onwards are the design description and design conclusion, and the parts further forward are the design principles and calculation processes, which need to be read in conjunction with the engineering documents... and it cannot be understood in a day or two."

Liu Hongbo explained.

"oh……"

Ed Steiner felt that this sentence sounded a bit wrong, but he was in extreme anxiety at this time and had no time to think about it.

I just quickly followed the other party's suggestion and jumped to page 377.

Sure enough, the most critical part came into view.

A graph of the calculation results of Mach number and equivalent airspeed.

"Oh~"

When the content on the monitor was magnified, a short but neat exclamation sounded in the entire engine room.

At this time, Liu Hongbo also spoke at the right time:

"I know that some friends are worried that we lack design experience, which will lead to problems in the final design plan."

This first sentence directly stunned everyone.

Because Liu Hongbo used French...

"Wait..."

Edelsteiner was so shocked that his eyes almost popped out:

"You can speak French?"

As for the engineers who just got together, their faces turned red and white.

It was quite embarrassing to say bad things behind someone's back and be discovered in person.

"I learned a little when I worked with the European Helicopter Company before."

Liu Hongbo smiled and replied:

"Of course, I am not very proficient, so my subsequent introduction will still be mainly in English..."

It is indeed not very proficient.

It can even be said to be stiff.

But it was enough.

Even those who were just watching the fun or questioning the situation, now they have adjusted their attitudes.

It is obvious that since the other party can directly point out the problem, it means that at least they are not unprepared.

Looking at the French people in front of him who were still in shock, Liu Hongbo felt relieved.

At this time, he had only one thought in his mind;

"Fuck... So when Mr. Chang talks about the design plan on the stage, is he so happy?"

Of course, this is just a thought, and he must pretend to be serious on the surface:

"In short, please rest assured, Dr. Edelsteiner, and all colleagues present, although our research in the field of jet airliners has just started, we can restore the "transonic dip" phenomenon of the aircraft flutter boundary curve in the wind tunnel test through calculation..."

When this was said, everyone was shocked.

With the increase of Mach number, the flutter speed of most aircraft will gradually decrease in the subsonic region, reaching a minimum near Mach number 1, and then the flutter speed will gradually or suddenly increase.

This is also the main reason why the maneuverability of many aircraft is the worst in the transonic range, but gradually recovers in the supersonic range above Mach 1.4.

In fact, as early as the early 1960s, NASA had discovered this law through a large number of wind tunnel tests and provided a standard example using the AGARD 445.6 airfoil.

However, before this, no one had ever been able to reproduce this problem in the design calculation process.

"But... this..."

The female engineer who had just expressed her doubts was almost incoherent at this time:

"The nonlinear aerodynamic performance of different airfoils in the transonic stage is completely different. If it can be calculated... could it be that you have solved the N-S equation from a theoretical level?"

"Uh... that's not the case."

Liu Hongbo was also speechless about this overly jumpy guess:

"If the smoothness and solvability of the N-S equation were proven, I think you would have seen the relevant news a long time ago... just like when the Poincare conjecture was proved two years ago."

"In fact, we have discovered a new turbulence model that takes into account both efficiency and accuracy in the transonic range. You can call it 'Chang's turbulence'..."

"The specific engineering calculation process involves our commercial secrets, so I'm sorry I can't disclose it, but you can find and use this turbulence model itself in the 2.0 version of TORCH Multiphysics software to be released next month..."