Chapter 66 Solution [Please order first! ! ! 】(15)

After confirming that there is no problem with the accuracy of Chang Haonan's simulation method, the remaining work is to conduct a few more test flights to obtain detailed data on the aircraft when aileron reversal occurs.

With the efforts of the test flight team, the two prototypes 03 and 04 took off in turns, and the entire test flight was completed in just five days.

It was finally proven that Chang Haonan's calculation was completely correct. When the airspeed and elevation angle of an aircraft with bombs reach a certain value, aileron reversal will occur.

In fact, even if the mount is adjusted to two Aspades plus two Thunderbolt 8s that are closer to the actual combat status, this situation is still unavoidable, but it will appear later.

With the end of the test flight, Chang Haonan's system status also changed.

[Research points: 85

Theoretical level: LV2 (0/10000)

Engineering experience: LV1 (70/1000)

Management ability: LV0 (65/100)

Comprehensive ability: LV1

Projects in progress: 0

Projects that can be carried out: 1]

Compared with before, it has gained 10 scientific research points and up to 50 management experience points.

It can be considered a good harvest.

……

The afternoon of the same day when I got the complete test flight data.

It’s the same conference room, with the same people as last time.

Just because of Chang Haonan's unusually outspoken performance, today he, Yao Mengna and Lin Shikuan were directly invited to the seat near Yang Fenghao in front of the conference table.

This time, the atmosphere in the venue became much more solemn——

Aileron reversal occurs at less than twice the speed of sound, and the corresponding deflection angle when aileron reversal occurs is only 10°.

The corresponding roll rate is less than 30° per second, and it takes 90 seconds to perform an ordinary 3° roll away action.

This is completely unacceptable for an interceptor aircraft that focuses on high-altitude and high-speed capabilities.

So everyone ruled out limiting flight performance via flight controls from the start.

The wings had to be modified.

In 1996, people were not so shy about smoking in public places, so not long after everyone entered the conference room, the whole room became filled with smoke.

Chang Haonan hated the smell of cigarette smoke, so he moved slightly closer to the window.

Of course, the first one to speak was Yang Fenghata:

"Don't be discouraged. Since the problem exists, it is better to find it as early as possible. The earlier, the less progress we will delay. So from this perspective, it is the first time that Comrade Xiao Chang and Comrade Xiao Yao joined the August 3rd Project Project Team. After that, it’s a great gift for us.”

After a moment of silence, I don't know who was the first to take the lead in applauding.

What followed was thunderous applause.

This sentence not only praised Chang Haonan and Yao Mengna, but also boosted the morale of the entire project team.

After the applause gradually died down, Yang Fenghata continued:

"In order not to delay the test flight progress of Project 03 as much as possible, I decided to transfer the No. 04 prototype to Yanliang early next month according to the previous plan, and conduct a test flight that does not involve the project with bombs first, while the No. 112 verification aircraft will be kept. At Factory , preparations are being made for modification."

"Considering this, the No. 03 aircraft can no longer be regarded as a full-state verification machine. Therefore, after the wing problem is solved, a No. 05 verification machine will be built using backup parts and will conduct a full-state verification flight together with the No. 04."

"In this way, we can have relatively ample time to improve the wing."

A few minutes later, deputy chief designer Liu Ming, who was sitting first on Yang Fenghata's left hand side, finally spoke.

"Comrades, according to the data obtained from the test flights in the past few days, the reason for the aileron reversal is not complicated, but is the common problem of boundary layer accumulation."

"The simplest solution is to add a pair of wing blades on the wing where the lateral flow is most intense."

Chang Haonan nodded slightly.

As expected, the engineers of Institute 601 chose the same solution as later generations.

In fact, from the current perspective, it is indeed the best way.

During the flight of an aircraft, the airflow on the upper surface of the wing will automatically flow toward the wingtip, and accordingly, the boundary layer will gradually accumulate toward the wingtip.

The accumulated airflow will eventually separate at the wing tip, and this separation process will bring a large shear force, causing obvious elastic deformation of the wing, thus causing the aileron efficiency to decrease or even become counterproductive.

To avoid this situation, the simplest way is to add a pair of baffles on the upper surface of the wing to block the lateral moving airflow.

That is, the Wing Knife.

However, some people still put forward different opinions

"But Mr. Liu, the current J-8-3 already has two pairs of wing blades on its wings. If we add another pair, would it be a bit..."

Although the wing blade is simple and effective, it is not without cost. The essence of its working principle is to cause the leading edge vortex to break early, thus reducing the lift coefficient and stall angle of attack, which still has a certain impact on flight performance.

Moreover, designing too many wing knives will not look good in terms of appearance.

"Is it possible to consider merging three sets of small wing blades into one large set of wing blades, like the J-6?" another person asked.

But it was quickly rejected:

"That can only reduce a little weight, but it will have a greater impact on lift and over-stall capabilities. For an aircraft as big as the J8-3, the gain outweighs the loss."

The heated discussion lasted for about half an hour, but still no solution was agreed upon by everyone.

Finally, someone turned their attention to Chang Haonan, who had been looking down at the report in his hand without speaking.

"Dr. Chang, since you discovered this problem, do you know if there is a better solution?"

The conference room gradually became quiet.

Chang Haonan stood up and walked to the blackboard with test flight results and design drawings.

"First of all, I want to tell you some good news." Chang Haonan turned around, looked at the engineers in front of him and said:

"After the efforts of the entire digital design team in the past few days, the parametric modeling of the aerodynamic and structural design of the J-8-3 prototype has been basically completed, so the time spent on modifying the design should be lower than expected."

Another unusual result.

The optimization design of the aircraft aerodynamic shape requires the evaluation of various aerodynamic shapes, so the aircraft aerodynamic shape needs to be repeatedly modified in order to improve its aerodynamic performance.

Once you have a parametric model, you can drive changes in the geometric model by changing the design parameters, thereby greatly shortening the geometric model modeling cycle.

Lin said that the Broadband people had been working on a task for a year and a half without making much substantial progress, but Chang Haonan solved it in less than ten days after coming over.

Although the latter did not mention his name, almost everyone agreed that this was a manifestation of his hidden merit and fame.

Then there was another burst of applause.

Chang Haonan stretched out his hand and pressed it down to signal to keep a low profile:

"As for the improvement plan for the wing, I do have an immature idea." Chang Haonan picked up an unsharpened pencil and drew on the design drawing and continued:

"The idea of ​​adding a pair of wing blades is okay, but according to my simulation results, the area with the densest cross-airflow on the wing surface is near the trailing edge of the wing."

"Therefore, I think the existing upper and lower aileron hinge fairings can be expanded into trailing edge wing blades. This increase in dead weight is almost negligible, and the look and feel is closer to the original bi-wing blades."

"At the same time, leading edge devices can be introduced into the wing design, such as leading edge flaps or leading edge slats. This can not only compensate for the impact of wing blades on the lift coefficient and stall angle of attack in the middle and low speed range, but can even greatly Improve the aircraft’s low-altitude and low-speed performance!”