Chapter 982: So Mr. Chang is so happy every day?


    ?Other than 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?”


    ?The few people were standing in a relatively remote place, and they also saw that the Chinese man seemed not to understand French, so they were not worried about being overheard.


    “If we only talk about critical speed, I wouldn’t be 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 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 a supercritical airfoil 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.


    ?Hence, 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 so..."


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


    “Probably... uh... it should be about 6 years ago. At that time, the Chinese people and Finmeccanica Group designed a regional passenger aircraft. Of course, it was a joint design, 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 when I went to Egypt on a business trip. For a propeller aircraft, the noise and vibration levels are first-class..."


    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 passenger aircraft, 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 changing to 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.


    I feel a little guilty now.


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


    And it was pretty much the same for himself.


    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 turn directly to page 377.”


    "What?"


    ?Ed Steiner subconsciously stopped the movement of his hands.


    “Page 377 and beyond are the design description and design conclusion, and the previous parts 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 strange, but at this time he was in extreme anxiety and had no time to think about it.


    Just follow the other party’s suggestion and jump to page 377.


    Sure enough, the most critical part is directly what catches the eye.


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


    “Oh~”


    ??When the content on the monitor was enlarged, a short but neat exclamation suddenly sounded throughout the computer room.


    At this time, Liu Hongbo also spoke appropriately:


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


    ?This first sentence immediately stunned everyone.


    Because Liu Hongbo used French...


    "etc…"


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


    “Do you speak French?”


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


    There is quite a sense of embarrassment in saying bad things behind someone''s back, only to be discovered in person.


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


    Liu Hongbo smiled and replied:


    “Of course, I’m not very proficient in speaking, so my subsequent introduction will still be mainly in English…”


    Really not very skilled.


    It can even be said to be blunt.


    But enough is enough.


    ?Even those who just looked at the fun or had a skeptical attitude have now corrected their attitude—


    Obviously, since the other party can point out the problem directly, it means that at least he will not be unprepared.


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


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


    “Holy shit...so is Mr. Chang always so happy when he talks about design plans on stage?”


    ?Of course, just thinking about it, I still have to pretend to be serious on the surface:


    "In short, please rest assured that Dr. Ed Steiner and all colleagues present here, although our research in the field of jet airliners has just started, we can already calculate the ''transonic speed'' of the aircraft flutter boundary curve in the wind tunnel test. Transonicdip’ phenomenon…”


    As soon as these words came out, everyone in the audience 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 speed range, but gradually recovers when entering the supersonic speed 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 also provided a standard calculation example using the AGARD445.6 airfoil.


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


    “But…this…”


    ??The female engineer who had just expressed her doubts clearly could not even speak coherently 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 theoretically?”


    “Uh…that’s not the case.”


    Liu Hongbo was also speechless at this overly jumpy speculation:


    “If the smoothness and solvability of the N-S equation were proven, I think you would have seen the relevant news long ago... just like when the Poincaré conjecture was proven two years ago.”


    “Actually, 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 am sorry not to reveal it, but the turbulence model itself can be found and used in the TORCH Multiphysics software version 2.0 released next month...”


    (End of this chapter)