Generally speaking, it is the flight control rate design of the aircraft's fly-by-wire control system that has led to the current result, but this kind of aircraft is hydraulically operated!

In this era, there are not many test pilots who know the coupling oscillation of pilots, because everyone has never encountered it, and Tang Gang has been tirelessly studying various problems in test flights during this time, so he can be regarded as understanding this kind of failure.

However, how it can appear in one's own body, this is not understood.

"This kind of failure is not necessarily all fly-by-wire." Qin Feng said on the side: "Even if it is an aircraft with a hydraulic operating system, if there is a lag in operation, this kind of problem may occur. ”

It is very high, in fact, the essence is that the operation lags, it should have been a pusher, but as a result, the system reacts slowly, and when operating the rudder surface, it is time to pull the rod, which of course adds fuel to the fire.

Operation lag, this did not appear on the J-7, but it appeared on the J-7, of course, this is because of the difference between the two, the J-7, there are operating levers before and after, is it because of the increase in the cylinder and oil circuit, and finally leads to this kind of problem?

As soon as Qin Feng explained this, Tang Lao also understood: "It's possible, but we still have to investigate it clearly to see if this problem is an accident or an inevitability." ”

This reason is very complicated, of course Donald knows that it is easy to adjust, but after adjustment, will there be other problems? After all, this is at supersonic speed, and it is the maximum speed, if it is immediately adjusted just because of this one, then when it comes to the subsonic range, will the lever be too sensitive? If it's particularly sensitive, I'm afraid it's not convenient.

This is a contradiction, high altitude and low altitude, high speed and low speed, the amount of rods is different, and the response speed of the operating rod is also different.

This is a drawback of surveying and mapping imitation, knowing it, not knowing why, not knowing how people design it, don't dare to change it directly, otherwise, there may be more problems, just like writing a program, the kind of ancestral code, as long as it is slightly modified, there will be a terrible number of crashing bugs.

Now, it makes sense for Tang Lao to think about it like this, Qin Feng pondered for a moment and said, "It seems that we need to fly up again to see if a similar situation occurs." ”

I have to make the fault happen again, try a few more times.

Knowing that there are tigers in the mountains, they prefer to go to the tiger mountains, although they know that it is very dangerous, but they must keep repeating this danger in order to finally find the right way, which is their duty.

"I'll go!" Tang Gang said.

"Forget it, I'd better go up." Qin Feng said: "I'll feel it alone, maybe it's more real, you are here, analyze the data first." ”

Qin Feng didn't let Tang Gang go up, of course, not because it was more real, but to protect Tang Gang, after all, Tang Gang had just started the test flight, he was very rusty, and he was not as quick as Qin Feng.

Moreover, this pilot coupling shock is definitely not said to happen every time.

So, Tang Gang could only be on the ground, watching Qin Feng get on the plane again, take off, and start the next test flight.

If you want to reproduce the failure, it is best to maintain the same altitude, speed, and all situations are the same, Qin Feng continued to accelerate to the maximum speed at the same altitude in the same way just now, and then, turn off the afterburner.

At the moment when the afterburner was turned off, sure enough, he had the same feeling, and the nose of the fighter was deflected downward! So, Qin Feng pulled up the operating lever.

But what, don't you feel it? As soon as he pulled like this, the plane was flattened directly, and there was no such coupling shock? Unless Qin Feng continues to operate by himself?

Reverse operation, it is difficult for ordinary people to do it, Qin Feng after reducing to subsonic speed, continue to turn on the afterburner, fly to the maximum speed, as in the situation just now, turn off the afterburner, the plane bows its head, and then the lever is flattened, and there is no more shock.

What's going on?

After trying three times in a row, Qin Feng did not find that the fault reappeared, so the plane returned.

"I didn't find the fault just now, maybe it's a problem with my operation." At this time, the data had been analyzed, and Tang Gang asked Qin Feng.

Qin Feng frowned: "Pilot coupling shock, not every time will happen, but this kind of accident signs, it must be thoroughly analyzed, now, we have the first problem to solve, that is, why as soon as we turned off the afterburner, the nose of the plane suddenly sank." ”

Although the accident of the pilot's coupling shock did not occur again, but now after turning off the afterburner, the nose sinking is a certainty, and on the J-7, this situation has not occurred.

"yes, that's where we get weird, why is this happening?" Donald was also thinking the side.

Of course, they want to figure out all the problems, but they have been building the J-6 before, and they are not familiar with the J-7 at all, so it is difficult for them to find out the cause of the failure immediately.

Perhaps, you have to go to the test flight institute to find an expert.

As long as the first flight is no problem, you can go to the test flight institute to fly the rest of the subjects, of course, there is a disadvantage to doing this, that is, the delay will be longer, they originally planned to fly everything that can fly here, and then go to the test flight institute to fly complex subjects.

"I think it's about comparing the differences between the two types of aircraft." Qin Feng said: "There is no Jian-7, Jianjiao 7 has appeared, let's see, what is the difference between these two aircraft, which led to this result?" ”

It's a bit like everyone is here to find faults and compare the differences.

Hearing Qin Feng's words, everyone thought about it seriously.

The difference, first of all, is the addition of a cockpit in the back, as well as the corresponding equipment, but isn't it the same for the MiG-21 trainer aircraft? This has no effect on the aerodynamic layout, so it shouldn't be.

Problems with pneumatics? This is the first thing that comes to everyone's mind.

And Qin Feng finally aimed his gaze at the back of the cockpit.

Because the instructor's cockpit occupies a certain amount of airframe space, resulting in a decrease in fuel in the fuselage, the back of the aircraft looks a little bulging, because a larger capacity fuel tank is placed in the back of the aircraft to compensate for the reduction in fuel.

Could it be a problem here?

Although it flew three more times later, Qin Feng seemed to feel that the problem of the nose sinking was lighter and lighter each time.

Is it pneumatic?

If it's not pneumatic, it's another side of the story, isn't it?

"Donald, please fill up the plane, and Don and I will fly again!" Qin Feng suddenly thought of something, patted his thigh and said.

Fly again?

The sun is about to set!

。