In the sunset of the sunset, Qin Feng and Xiao Tang took off again, this time, just like last time, Tang Gang sat in front, Qin Feng sat in the back, flying three times a day, it was definitely a great test of physical strength, after flying, I knew that flying was indeed physical work, but now Qin Feng is still a young man, and he is quite energetic, and now he still looks like he is letting go, let Tang Gang operate comprehensively.

It's the same as it was in the morning.

Fly to a high altitude, turn on the afterburner to reach the maximum speed, and then turn off the afterburner again.

Sure enough, at the moment of turning off the afterburner, you can feel that the momentum of the plane's head down is the greatest! Tang Gang, as at the beginning, immediately began to pull the operating lever to change, and then, the plane began to tilt up, and the operation was overdone!

Tang Gang pushed forward again, and after two blows, the plane shook sharply.

With the first experience, Tang Gang let go of the operating stick without Qin Feng's order, and the fighter quickly ended the back and forth oscillation and was tamed again.

Qin Feng in the back cabin, with a satisfied look on his face, he finally found this problem!

When the fighter plane slid back to the runway, night was almost falling, Tang Gang's operation was very stable, and he was not nervous at all because of the deterioration of meteorological conditions, the fighter plane landed smoothly, slid back to the tarmac, and handed over to the maintenance personnel waiting there, and Tang Lao and others were also waiting on the side.

"Xiao Tang, let's talk about it first." Standing next to the plane, Qin Feng signaled to Xiao Tang.

As a test pilot, in addition to flying out of the fault and making the fault repeat, it is also necessary to use your brain to think about how the failure came about, many excellent test pilots can accurately judge the location of the fault at once, so that they can quickly adopt the right decision when it is critical, and now Qin Feng has been cultivating Tang Gang's ability.

"Compared to the second time, we had two people and at the same time, we had all the fuel tanks full, so, I think, that's where the fault came in." Tang Gang said: "Our focus has changed. ”

The design of the fighter is a science, and the center of gravity of the fighter needs to coincide with the center of lift, otherwise, only fly-by-wire control can be tamed, and hydraulic operation is simply a disaster.

Therefore, when Tu Lao was improving the J-7, although the radar in the nose became lighter, he still needed to add a counterweight of lead, just to adjust the center of gravity.

However, this adjustment is all in the horizontal plane, and the center of gravity is somewhere in the middle of the body, which coincides with the position of the center of lift, so that there will be no problems.

But now, the final problem is not the problem of the center of gravity in the horizontal plane, but the problem of the upper and lower axes!

"Yes, compared with the original J-7, we have changed to a two-seater, the height has been increased, and at the same time, in order to increase fuel, there is an additional large fuel tank behind the pilot, so that our center of gravity is biased."

The problem now is that the center of gravity is on the top! The fuel tank on the back of the plane is hundreds of kilograms, and there is an additional pilot on it, which is also dozens of kilograms, so that the center of gravity has moved upward.

In that case, what is the result?

It is said that there will be no problems, but in some special cases, there will be special problems, the center of gravity is shifted upward, resulting in the thrust axis of the engine and the center of gravity are not on the same plane, and the center of gravity becomes higher!

Only on one axis, it is the most suitable, and now that the center of gravity is high, what will happen?

After turning off the afterburner, the thrust of the engine decreases suddenly, and a bowing moment is generated, and the current speed is quite large, and the center of gravity is raised, so it causes a lag in operation, and the tie rod intervenes, and it is easy to form an up and down oscillation.

This kind of failure does not occur every time, the center of gravity becomes higher is an important factor, so when Qin Feng goes up alone, the center of gravity is lowered, and at the same time, the fuel tank on it is empty, so such a failure will not recur.

It's so bizarre, and it's so reasonable, it can all be explained now.

The expression on Donald's face was very solemn: "Indeed, the analysis is very correct, but how should we modify it?" ”

In the test flight, if there is a problem, it must be solved, and the concussion induced by this pilot is quite dangerous and must be solved, but how to solve it is very difficult.

Remove the newly added fuel tank from the back? In this way, the airplane will be kept in space for a shorter time!

Changing the operating system? That's simply impossible, they don't have that technical strength yet, so how to solve it is a big problem.

If it can't be solved quickly, I'm afraid it will seriously affect the progress of the test flight.

Donald led all the staff to complete the mapping and imitation in the shortest possible time, but now, it is not easy to solve the problem, and his face has begun to have a sad face.

"This problem is also very simple to solve." At this moment, Qin Feng spoke: "When we train, just pay a little attention." ”

A little on the lookout? Donald was also confused when he listened, what kind of solution is this?

If it is fly-by-wire control, it is a problem with the design of the flight control rate, and it must be modified, otherwise there will be a problem, but now it is not, now it is just an accidental situation, then, it is okay to write the training materials-for-tat.

"When flying, if it is full of fuel, two members, and it is flying to the maximum speed, at this time, do not turn off the afterburner immediately, you can reduce the afterburner, gradually turn off, let the speed slow down, at the same time, if there is such a situation of bowing your head, do not operate immediately, wait for the speed to drop down and then operate, you can do it." This is the opinion given by Qin Feng.

The afterburner of the fighter has multiple gears, and the power obtained by different gears is different, and it is definitely not that when the afterburner is turned on, it is the maximum thrust immediately.

The afterburner is also divided into several different levels, and there is even a continuously adjustable afterburner, from the minimum afterburner to the maximum afterburner is continuously adjustable, and different power needs can be obtained.

Don't just turn it off, reduce the afterburner first, this is enough, this is also the easiest way to tell the pilot, how you want to fly this plane.

In fact, this is to let people adapt to the aircraft, has been outdated, after all, now the new concept, are the plane to adapt to people, when people sit in the plane, how to move, the flight control system will restrict, you can not do the action, easy to cause stall and other actions, the flight control system will restrict you to do this, so that you can achieve worry-free flight.

Do you want to get into a stall tailspin? No way, don't worry, fly as much as you want.

But not now, the current second-generation aircraft, are people to adapt to the aircraft, where is the envelope of the aircraft, what actions are dangerous, the pilot must know clearly, in flight, to avoid entering such a situation.

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