The military-industrial scientific research system of the academic master.

In addition to Liu Hongbo and Ed Steiner, other people in the computer room were naturally taking advantage of this opportunity to communicate in low voices.

In French, of course.

"I remember that the wing design was commissioned to the Chinese at the end of October last year, and it has only been about four months since then..."

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

"At that time, the starting point for optimizing our critical speed was around Mach 0.8. In such a short period of time... could we really optimize it to the design requirement of 0.95?"

The few people were originally standing in a relatively remote place, and they also noticed that the Chinese man did not seem to understand French, so they were not worried about their conversation being overheard.

"If you're only talking about the critical speed, I'm not too surprised..."

The next person to speak was another middle-aged female engineer sitting on a chair:

"In fact, there are many mature technical means to increase the critical speed to a level close to Mach number 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 position where the drag diverges 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 wings with a larger aspect ratio without changing the total weight.

That is, thinner.

As early as the early 300s, Airbus had already adopted supercritical airfoils when designing the A.

By the beginning of the 21st century, in the field of pure aerodynamic lift design, it was indeed no longer considered 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 wind tunnel or test flight data accumulation. So everything may seem normal on the surface, but once they actually enter the testing phase, troubles will arise one after another..."

Obviously, not everyone agreed to entrust the wing design task to China.

"If you mean the wing flutter problem, I don't think so..."

A bald old man who had been staring at the computer screen turned around at this time:

"About... uh... about six years ago, the Chinese designed a regional jet together with Finmeccanica. Of course, it was a joint design, but the Italians had little involvement in the hardware."

"In my impression, the wing design of that aircraft is quite good and very competitive among aircraft of the same class."

"You have been working in the headquarters, so you may not have any impression, but I once took a ride on it when I was on a business trip to Egypt. For a propeller plane, the noise and vibration levels were first-rate..."

It is not difficult to hear from his words that he has a high opinion of the Xian MA60.

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

The female engineer just now replied:

"I heard that it did have a significant impact on the ATR72 and Dash8 markets. However, even at the maximum speed, turboprop airliners cannot exceed Mach 0.5. The flutter problem in that speed range is completely different from that in the transonic range..."

"This……"

A well-reasoned rebuttal left the other party speechless:

"That's true..."

"..."

While everyone was chatting, the data in the first batch of hard drives had been transferred. While the technicians were switching to the second batch, they also opened the project documents that had been transferred at Edsteiner's request.

For a moment, no matter whether they were skeptical or determined, their eyes were all focused on the computer screen in the center of the computer room.

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

Edsteiner quickly skipped over the meaningless content such as the project background, and prepared to scroll directly to the key points -

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

Although he had been chatting with the former, Edsteiner did not ignore the whispers of those people in the corner.

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

Now I feel a little guilty.

If, as the female engineer said, there was a big problem with the wing during testing, it would definitely be a devastating blow to the project progress.

And it was much the same for him personally.

Fortunately, at this time, Liu Hongbo, who was standing next to him, looked at Edsteiner, whose anxiety was almost written on his face, and lent a helping hand in time:

"You can just turn to page 377."

"what?"

Ed Steiner subconsciously stopped what he was doing.

"Page 377 and onwards are the design description and design conclusions, and the part before that is the design principle and calculation process. You need to read it in conjunction with the engineering documents... and it will take more than a day or two to understand it."

Liu Hongbo explained.

"Oh……"

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

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

Sure enough, the most crucial part is what comes into view.

A graph showing the calculated Mach number versus equivalent airspeed.

"Oh~"

When the content on the monitor was magnified, a short but uniform exclamation instantly rang out in the entire computer room.

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

"I know that some friends are worried that our lack of design experience may lead to problems with the final design plan."

This first sentence stunned everyone.

Because Liu Hongbo used French...

"and many more……"

Ed Steiner was so shocked that his eyes almost popped out:

"You speak French?"

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

It's quite a bit like saying bad things about someone behind their back and then being caught in person.

“I learned a little bit when I was working with Eurocopter before.”

Liu Hongbo replied with a smile:

"Of course, I'm not very fluent in it, so my subsequent introduction will still be mainly in English..."

Not very skilled indeed.

It can even be said to be stiff.

But it is enough.

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

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

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

At this moment, there was only one thought in his mind;

"Fuck...Is it always this cool when Mr. Chang talks about design plans on stage?"

Of course, this is just a thought, and I still have to pretend to be serious on the surface:

"In short, please rest assured, Dr. Edelsteiner and all colleagues present here. Although our research in the field of jet airliners has indeed just started, we can already restore the 'transonic dip' phenomenon of the aircraft flutter boundary curve in wind tunnel tests through calculations..."

When these words were spoken, everyone in the room was shocked.

As the Mach number increases, 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 worst in the transonic range, but will gradually recover when entering the supersonic range above Mach 1.4.

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

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

"But...this..."

The female engineer who had just expressed her doubts could hardly speak coherently:

"The nonlinear aerodynamics of different airfoils at transonic speeds are completely different. If you can calculate it... could it be that you have solved the NS equations theoretically?"

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

Liu Hongbo was also somewhat speechless about this overly leap-forward guess:

"If the smoothness and solvability of the NS equations had been proven, I think you would have seen the 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 combines 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 cannot disclose it. However, you can find and use this turbulence model in the 2.0 version of TORCH Multiphysics software to be released next month..."