At the front row of the conference table, Yang Fenghata and several other project team leaders also gathered together to communicate in a whisper.

Before the 83 Project, the J-8B had been tested with 4 rounds of PL8 short-range air-to-air missiles.

According to the results at that time, the adverse effect of the missile on rudder surface efficiency was within acceptable ranges.

However, the Asped is an over-the-horizon air-to-air missile with a large size and weight, and it is the first time that the Huaxia aviation industry has come into contact with the design problems related to it.

As Chang Haonan said just now, the aerodynamic analysis at high speed and high angle of attack is still based on experience.

Since I haven't seen it before, I can't talk about any experience, let alone analysis.

Similar to the situation at the time of the MA60, the problem involving the rudder surface is difficult to restore by the wind tunnel alone.

However, if the flight test is carried out in one step directly according to Chang Haonan's calculation results, the risk is relatively high.

The safest way is, of course, to carry out a large number of test flights, starting from relatively mild flight conditions, and gradually approaching the theoretical position of aileron reaction to ensure maximum safety.

But in this case, progress may be slowed down by weeks or even months.

So several people discussed it for a while, but they couldn't come up with a solution that everyone felt was feasible.

In the back of the room, the discussion was even more lively.

Even Chang Haonan was surrounded by a lot of people, looking at the report he brought.

In fact, what was just taken to the front and projected onto the screen through the projector was only the final conclusion obtained after his high degree of condensation and summary.

In order to reach this final conclusion, he has spent the past day and a half analyzing many problems, some to verify the accuracy of the algorithm, and some to provide data for the calculation of aileron efficiency.

These analyses are not of any guiding significance for the 83 Project, which has a high degree of completion, but for the designers around Chang Haonan, compared with the somewhat shocking conclusion just now, the content they are more familiar with is more attractive.

"The calculation of this part is...... When the aileron is deflection, the pressure difference between the upper and lower wings? ”

An engineer with thick glasses and gray-haired hair picked up a few pages from the report, flipped through them a few times, and asked in a somewhat surprised tone.

"That's right, this is the distribution of the pressure difference between the upper and lower wing surfaces when the aileron is deflected up and down by 3° and 5° respectively at Mach 0.6 and 10° angle of attack."

Chang Haonan glanced up at the contents of the other party's hand, revealing a smile that had succeeded in his plan.

What the other party was holding in his hand happened to be a map of the distribution of the pressure difference between the wings that he had made in order to show off his skills.

Originally, the output of the computer was just an ordinary line chart made up of discrete data points, but it took him about three hours to plot the data on the line chart on the cross-section of the wing.

For those who are accustomed to seeing scattered data, seeing this kind of three-dimensional cloud map for the first time is no less shocking than seeing a movie for the first time.

"This data is not much different from the results we got during our previous test flights, the up-and-down deflection of the aileron has the opposite effect, the downward deflection increases the lift and drag of the wing, and the upward deflection decreases the lift and drag of the wing."

A middle-aged female engineer next to her leaned over and looked at it a few times and commented:

"And Dr. Chang's expression is very intuitive, especially it is easy to see the trend."

"Yes, that's one of the advantages of our digital design and simulation." Chang Haonan nodded and replied:

"It is clear that the difference in wing lift on both sides causes the aircraft to roll in motion, and the difference in wing drag on both sides causes the aircraft to deflect and cause sideslip. Sideslipping, on the other hand, creates a moment that counteracts the roll effect of the ailerons, thus reducing the efficiency of the ailerons. ”

"At low speeds and angles of attack, mainly in the subsonic range, this drag is the main reason for the reduction of aileron efficiency, but in general the impact is minimal and can be mitigated by differential ailerons."

Chang Haonan said this, took out another page from the report in his hand and handed it over, and then continued:

"And once you enter the supersonic range, or fly at a high angle of attack, the torque generated by the elastic deformation of the wing will quickly become larger, and it will become the main factor affecting the efficiency of the ailerons, which is what I said before."

"Looking at this table, after considering the elasticity of the wing, the ailerons should have provided a clockwise rolling moment, but it is obvious from the calculation results that the bending moment of the left wing root is smaller than that of the right wing root, which indicates that the aircraft in this state has produced a counterclockwise roll torque around the roll axis, that is, the aileron reverse effect has occurred."

“……”

As Chang Haonan's explanation deepened, he could even feel that the attitudes of the people around him towards the digital design team, and even towards the digital design itself, were changing at a speed that was visible to the naked eye.

The main reason is that Chang Haonan has come up with several simulation results in a row, all of which are consistent with the test flight results they got before, and the gap is not big.

That's really convincing.

Many people still had a disdainful or disdainful expression when they first came over, but after listening carefully to his explanation, their expressions or eyes changed drastically.

At this time, Yang Fenghata and the others also ended the discussion and motioned for everyone to return to their positions.

"Dr. Chang, now I'm really convinced of you."

After the crowd around Chang Haonan gradually dispersed, Lin Shikuan, who had just been squeezed outside, sat back next to him with admiration on his face:

"The gray-haired old-timer just now is called Xu Jin, and he has always felt that our digital design team is a complete waste of project resources, and every time we have this kind of meeting, they will target us intentionally or unintentionally, but this time they only asked a question and then didn't say a word."

"It's understandable, old comrade, that there are concerns about new things, but as long as the facts are strong enough, I believe that anyone who pays attention to science can be convinced."

Chang Haonan didn't look up, but replied while sorting out the report that had just been scrambled.

At this time, Yang Fenghat, who was in front of the conference room, also opened his mouth again:

"I think after the exchanges and discussions just now, everyone should be able to see that the question raised by Comrade Chang Haonan is worthy of our serious consideration, so the focus of our next step is to verify when the aileron reaction will appear in the case of bullets."

If Yang had made such a decision twenty minutes ago, he might have encountered some opposition, but after circulating the report just now, everyone had some trust in Chang Haonan's simulation results.

It's just that in this way, the finalization of the design of the 83 project is bound to be delayed.

However, just when everyone was worried about the progress of the project, Chang Haonan spoke again.

"I think that the test flight verification work on the aileron reaction can be divided into two stages, and if it goes well, it should not delay too much progress."