"Of course that's fine, but I need to know what you're going to say first, so I'm so prepared that if something goes wrong, I won't be able to get off the stage."

Lin Xikuan agreed to Chang Haonan's request without much thought.

The main thing is that he is about to have a psychological shadow on such a thing as speaking.

After all, everyone else has made xx progress in reporting work, and even if there is nothing worth saying, everything is going well, so a comparison makes it seem that their group is very useless.

"It's nothing, it's just that I've basically determined that the existing wing design needs to be modified to a certain extent, as for the specific data, it's still being calculated, if nothing else, it will probably be available at this time tomorrow."

This overly exciting news made Lin Shikuan almost catch his breath.

He did think that Chang Haonan could let them fight a turnaround, but he never expected it to turn over so quickly......

"Dr. Chang, modifying the wing design is not a trivial matter, you ...... Are you sure you can come up with a workable change in just one day? ”

"No, no, no, you're mistaken, of course it's impossible to know how to change the wing in a day." Chang Haonan waved his hand and explained: "But it is enough for me to be sure that there is a problem with the wing and it must be modified." ”

"Ahem, ahem—"

Lin Shikuan, who had just barely recovered his breath, held back again.

This time, Chang Haonan did not continue to speak amazingly, but quietly waited for him to recover.

"But you're half right, if you use the traditional design method, then modifying the wing is really a matter of moving the whole body, but if you can achieve digital design, then this kind of modification will not delay the progress too much."

"However, the 83 project has not yet achieved a fully digital design." Lin Shikuan rubbed his chest that was a little stinging because of the violent cough just now.

"So you have to speed up the progress of the forestry workers, let the other teams of the 83 project see, the digital design team is not only not a burden, but can also help them greatly improve efficiency."

Chang Haonan's words made Lin Shikuan's eyes suddenly brighten.

"You're right, Dr. Chang, you're right......

The latter turned and strode out of the room, back to the computer room where everyone had just been.

"Overtime tonight!"

……

The day passed quickly, and after dinner the next day, Lin Shikuan took Chang Haonan and Yao Mengna to a large conference room.

After all, the progress seminar was attended by every group of the 601 Institute involved in the 83 Project, and some groups with more complicated work even had to send several people over.

As soon as the three of them entered the door, Yang Fenghat, who was sitting at the head of the long conference table, noticed this.

"Xiao Chang, Xiao Yao, how do you two feel in the digital design team? Did the forester familiarize you with the work? ”

Lin Xikuan, who heard this question, almost rolled his eyes - he didn't feel that these two needed him to be familiar with the work at all, and in the past day or so, he was led by the other party to advance a lot of progress.

It's no exaggeration to say that this day and a half has done more than they have done in the past year and a half.

After all, after working overnight last night, everyone in the group was convinced that they had finally gone in the right direction.

"We have been running in for more than a day, and we feel good, the forestry workers are very efficient, but they just didn't find the right direction before."

Chang Haonan took the opportunity to help Lin Shikuan and the others explain, and then received a grateful look from the latter.

When he was just reborn before, he had already thought about using the system to improve the strength of the entire Huaxia scientific research system.

But this can only be done step by step.

Chang Haonan, who was a military screw in the previous life, had no decent management experience at all, although he also brought several topics, but he did not need any complex division of labor and cooperation, so that the system's evaluation of his management ability was 0 level 0 experience.

This digital design group, which has a simple structure, relatively young members, and no shelves and burdens, is just suitable for a novice like Chang Haonan to exercise his management and organizational level.

That's why he will find a way to boost the self-confidence of Lin Shikuan and others.

In fact, since yesterday afternoon, the system has shown that Chang Haonan's experience in management ability has been slowly growing, and it has come to 15 o'clock after just getting Lin Shikuan's gratitude.

Just as the three of them were talking to Yang Fenghat, other project members who participated in the meeting also entered the conference room one after another.

After everyone had sat down as they had done before, the workshop began in earnest.

Because Chang Haonan had indeed not been in contact with J-8-related projects before, and the 83 Project did have a certain legend for this generation of military workers, he listened to it with relish throughout the whole process.

In general, the test flights of the three prototypes went relatively well, but some problems were also mentioned by some groups.

For example, the WP14 engine is still not mature enough, and in some specific situations, especially at high speeds, it will induce surge, but the probability of this problem is very low, so the specific cause still needs to be further investigated.

Or WP14, the engine life, especially the turbine blade life as a hot end component, is not ideal, and there is still room for improvement.

In addition, as a typical second-generation high-altitude high-speed interceptor, there are problems with the available overload at the stall angle of attack and high angle of attack in a specific speed range, which needs to be limited by the flight control software to avoid entering a stall or tailspin state.

In addition, the fire control equipment team said that the imitation progress of the PL11 air-to-air missile, a German-made model of Aspie that matched the 1471G radar, was so slow that they simply did not have enough ammunition for over-the-horizon attack tests.

Finally, there is a somewhat peculiar problem, when the J-8-3 uses the innermost pylon of the wing to launch the PL8 air-to-air missile, there will be a certain probability of inducing engine stopping.

The reason for this is not complicated, the PL8 missile's propellant is very heavy when it burns, and interference with the air intake tract when the inner pylon is launched can lead to insufficient air intake or air flow disorder.

It's just that this is the same problem as the slow progress of the PL11 missile in the previous one, and it needs to be solved by the missile research and development unit.

As for the problem of the WP14 engine, it is also not something that the 601 can handle, but even if the worst possibility is considered, the J-8-3 can also temporarily use the WP13F engine with slightly smaller thrust, and there will not be a situation where it will not be completely impossible to go to the sky.

Therefore, after listening to the previous report, whether it was Yang Fenghat, who presided over the meeting, or the team in charge of these work, the mood was still relatively comfortable.

"So finally, let the digital design team talk about their progress."

Yang Fengwan looked at Lin Shikuan, who was sitting in the back corner of the conference room.

Since the digital design team was not able to guide the design of the aircraft, they became almost outsiders to the 83 project, and were put to the end for a long time to report.

But this time, it was not Lin Shikuan who stood up, but Chang Haonan who was holding a report in his hand.

For most of the people in the room, this is a new face.

And in general, the presentation by the digital design team means that the workshop will be over soon, and everyone will be relaxed.

Many people have begun to whisper to each other.

"The information design team has completed an aerodynamic simulation of the J-8-3 aircraft in the past period."

"According to our calculations, when the aircraft carries two Aspide air-to-air missiles on the outermost two pylons at the same time, the efficiency of the ailerons will drop sharply under the large angle of attack, large aileron declination angle and large dynamic pressure, and there is even a phenomenon of aileron reaction."

The venue, which was still a little noisy just now, fell silent in an instant.

As soon as these words came out, not to mention the other people present, even Yang Fenghat, who already knew Chang Haonan's ability, his first reaction was to think that the simulation was wrong.

After all, these two people only arrived at the 601 Institute at noon the day before yesterday, and it has been less than 60 hours since the full battle.

In fact, Yang Bonghata had planned to introduce them to the project members after today's seminar.

Chang Haonan himself is facing such a scene for the first time, and now almost everyone's eyes are focused on him, with doubt, confusion and even confusion in his eyes.

But the more times like these, the more you have to show confidence and decisiveness.

So he paused for about two seconds before continuing:

"According to engineering experience, we can qualitatively know that the change trend of aileron efficiency and roll rate with dynamic pressure is closely related to the aileron declination angle and flight angle of attack, but the traditional linear aerodynamic analysis method cannot simulate such results, so the aerodynamic analysis at high speed and high angle of attack can only be based on experience, supplemented by a large number of wind tunnel and flight test data for correction."

"However, in the process of analysis, we introduced external nonlinear aerodynamic forces, and considered the elastic deformation of the wing structure, and successfully simulated the influence of angle of attack, wing load and aileron declination on the aerodynamic efficiency of the wing, and the final result is that once the aileron deflection exceeds 10° at Mach 1.4 speed and 12° angle of attack of the aircraft with 4 rounds of A bomb, the aileron counter-effect will occur."

“……”

Chang Haonan's explanation loosened Yang Fenghat's thoughts.

He knows very well that nonlinear pneumatics and structural analysis are what the other side does best.

Even when he agreed to invite Chang Haonan over, it was precisely because of his outstanding ability in these aspects.

The wing flutter problem of the Y-7 passenger plane of the 603 Institute was also solved in one day.

……

After a brief hesitation for a few seconds, Yang Bonghata coughed lightly twice, drawing everyone's attention to himself.

"Let me introduce that this is Dr. Chang Haonan, whom I invited from the research group of Academician Du Yishan of Beijing Airlines University to assist in the work, and his specialty is to use numerical methods for aerodynamic simulation and structural simulation."

The venue that had just been silent gradually sounded the sound of whispering.

Most people don't know what happened at 603, but the names of Jinghang University and Du Yishan are still somewhat convincing.

At least it should be much more reliable than 601's own digital design team.

Therefore, after Yang Fengbei pointed out Chang Haonan's identity as an outsider, everyone's attitude towards him changed from complete disbelief to suspicion.

Theoretically speaking, Chang Haonan's explanation just now is indeed tenable.

Ailerons refer to a small movable wing surface installed on the outside of the trailing edge of the wing tip, which is mainly used to generate rolling torque through differential deflection to make the aircraft do roll maneuvering, and is one of the most important steering rudder surfaces of the aircraft.

If the roll torque generated by the aileron cancels out the moment generated by the elastic deformation caused by the aerodynamic force on the wing, the aileron can no longer control the roll of the aircraft.

When the flight speed continues to increase and exceeds the reaction velocity, the rolling moment generated by the aileron will be less than the reverse moment generated by the deformation of the wing under the action of aerodynamic forces.

That is, when the pilot wants to control the plane to roll to the right, the plane will roll to the left due to the reverse moment.

This is a very fatal problem for formation flights and air combat.

The simplest solution is naturally to limit the rudder operation of the aircraft in the flight control software - since the aileron angle of more than 10° will be counterproductive, then I can write a command so that the aircraft cannot deflect more than 10° in the corresponding speed range.

In fact, many aircraft did this, and even earlier aircraft would simply lock the aileron deflection angle by mechanical structure to avoid danger in the first place.

The problem is that while this approach ensures flight safety, it also limits maneuverability, making the aircraft almost an iron rod that can only make small movements at high speeds.

If the result Chang Haonan said is true, it means that the maneuverability of the aircraft in the bombed state at 1.4 times the speed of sound will be severely limited.

This is clearly not good news for an interceptor.

"Dr. Chang Haonan, I would like to ask, what method do you use to calculate the effect of elastic deformation of the wing on efficiency? As far as I can tell, there doesn't seem to be a reliable empirical algorithm to deal with this yet? ”

On the other side of the conference room, a middle-aged engineer in a half-sleeved shirt raised his hand and asked.

"You're right, there's really no one reliable formula to deal with it, but that's exactly where the CSD/CFD coupling approach excels,"

"First of all, we calculate the aerodynamic performance of the wing under selected flight conditions based on the original aerodynamic model, and still treat the wing as a rigid model for analytical calculation."

"Then, the aerodynamic load on the fluid node on the surface of the wing is interpolated to the structural model node by the equivalent node method, and the structural deformation of the wing under this load is calculated."

"In the third step, the new coordinates of the wing feature points obtained according to the structural deformation are regenerated for grid regeneration, a new aerodynamic model is established, and then the next round of aerodynamic calculations is carried out, and the above process is repeated until the convergence conditions are met, and the convergence results can be obtained after 6-8 calculations."

"After the above three steps, the rigid lift and elastic lift of the wing in these two cases can be obtained, so as to calculate the aileron efficiency in the selected flight conditions."

"Finally, by analyzing the lift coefficients and deformations of the wings in flight by analyzing various calculation models and in flight, it is possible to derive their relationship with the aileron maneuvering, and if necessary, I also bring detailed calculations."

Yang Fenghat's face had become serious at this time, and he waved his hand to one of his assistants next to him, who then came to the back of the conference room, took a few pieces of paper from Chang Haonan's hand, and then placed them under the projector one by one.

Several line charts are projected onto the screen.

"This ......"

"The idea of the iterative approach should be correct, but if it turns out to be like this, then the project schedule may be ......"

"I didn't expect the digital design team to really be able to make something, whether the result is right or not, at least it looks like that......"

“……”

Obviously, although it is impossible to draw conclusions because of Chang Haonan's statement alone, everyone in the conference room has begun to take this calculation seriously.