While the two were chatting while circling around the plane, the ground staff from the 611 Institute had also begun to maintain the plane.

Although the J-7F has undergone a complete overhaul in appearance, it is still a MiG-21 in essence, and its performance in terms of maintainability is still relatively average.

The biggest improvement is that at Chang Haonan's insistence, a side-opening radome is used, so that there is no need to remove the entire head cone and put it on the ground when maintaining the radar equipment.

He reached out and touched the lip and radome of the air intake, which he had optimized by himself.

Although the details of the plane in front of me are different from the one shown in Professor Liu Hongbo's class nearly a year ago, the overall structure is still very similar.

Most of the projects that Chang Haonan has handled so far are key technology research and development or modifications of old models, which is still different from the J-7F, which "the plane I drew fell to the ground".

From a relatively close position, he could already tell that the radome of this plane actually had an old radar inside.

"This is 208A?"

At present, Huaxia's radar models are still on the eve of technological outbreaks, and there are only a few models that can be installed back and forth, among which they can really be called "radars" instead of rangefinders, and they can also guide semi-active radar projectiles, except for the J-8C 1471/1472, basically only 208A is left.

That is, the radar equipped with the J-8B in the past, and the Air Force used this model for the first successful completion of the target test of Aspide.

"Yes, the 14 1452 small-caliber radars originally planned to be developed are still being tested on the ground, and there is no way to install them for the time being, but we are going to demonstrate over-the-horizon interception capabilities this time, so we can only take this on top first."

Speaking of this, Lu Yuying also seemed to suddenly remember something:

"Would you like to take a picture? This time we brought our cameras with us. ”

Chang Haonan hesitated for a moment, and finally nodded:

"It's fine."

"It just so happened that I called the pilot comrades over, and I want to take a group photo with the foreign side later."

Hearing Lu Yuying say this, Chang Haonan noticed that in addition to the ground staff, there were also some staff members who were not wearing overalls, but were still busy.

He had already seen banners in the hands of these people, as well as traditional arts of the aviation industry such as the big red flower.

In the end, Chang Haonan and Lu Yuying stood on the side of the radome that had been opened and took a single photo.

At this time, a pilot in a blue cotton jacket trotted in the distance, and a white flight helmet with a red star in his hand.

The pilot is not fine after getting off the plane, he still needs to hand over to the ground and fill in the flight record, and this posture should have just arrived from there.

Originally, Chang Haonan felt that he had already asked everything he wanted to know before, and he didn't want to participate in the group photo of the meeting, so he was planning to go back to rest.

But as the pilot got closer, he realized that the other person turned out to be a familiar face.

"Comrade Zhang Jiujiang?"

The person who came was the flight instructor who drove a Jianjiao 7 to the sky to observe the separation of the airflow flow on the surface of the No. 03 prototype when Chang Haonan had just participated in the 83 Project.

In this year, there is no contradiction between the two identities of senior flight instructor and test pilot.

But the meeting was quite a surprise.

Zhang Jiujiang, who was directly called by name, also stared at Chang Haonan for a few seconds, and didn't remember the latter's identity until he got closer:

"You're the one from 601...... Engineer? Have you flown on my plane? ”

"Uh...... Yes, we worked well together that time. ”

As soon as Chang Haonan nodded, he heard Lu Yuying next to him interject:

"Lao Zhang, Xiao Chang can't be regarded as a 601 person......"

This topic is already considered daily for the former, but Lu Yuying feels that he should still emphasize it, lest the other party forget his promise to 611 a year ago.

Although this commitment has nothing to do with his project.

"Don't worry, Mr. Lu, when I helped them change the J-7 in Factory 172 during this time, I specially asked for a lot of data from the prototype test flight, which could be used when I was researching active stability control technology later."

Chang Haonan looked at Lu Yuying, who was nervous, and naturally understood the meaning of the other party's words, so he hurriedly spoke to appease him.

"Active Stability Control ......"

The degree of generalization of this term is indeed a bit high, and it is not even possible to directly judge which subsystem technology is used in the aircraft.

"This is something I've been thinking about since I did the flutter analysis of the wing of the MA60 for the 603 last year."

Chang Haonan, who knew that this was a new concept, took the opportunity to explain:

"Since the flutter that occurs in the wing can be controlled by active means, can it be controlled in a similar way, or at least predict the engine surge in advance?"

"Later, when I was in charge of improving the turbojet 14, I found that before the engine entered the surge state, there were actually some observable characteristics inside the compressor, and if I could intervene in time at this time, I could avoid entering abnormal working conditions to a large extent, or at least keep it in a state of rotational stall, so as not to cause damage to the engine and the aircraft itself."

Lu Yuying and Zhang Jiujiang, who were next to them, were all stunned after hearing this explanation.

Engine surge is one of the last failures that aircraft designers and pilots are willing to face.

Since it is a self-oscillating air, it is too late to save it once it really enters a surge state.

Especially when flying at low altitude, high speed or large overload, if the power is lost and the aircraft is unstable, there is a high probability that the plane will be destroyed and killed if it is not in time to deal with it.

However, it is also in these situations that surge is prone to occur.

This is how many first-class accidents are caused.

For pilots, even a second or two earlier in detecting a problem can largely avoid accidents.

"If that's the case, if you put a sensor inside the compressor, you can ...... it?"

Zhang Jiujiang was naturally the most excited.

"It's not that simple."

Chang Haonan smiled and shook his head:

"On the ground or on the test bench, the external airflow is relatively stable, and the accuracy of capturing abnormal states is relatively high, but in real flight conditions, especially for fighters that need to fly frequently and with large overloads, even if there is no surge, the flow of the compressor is relatively chaotic, and if you simply put a sensor, the false alarm rate may be very high."

For an automated control system, the severity of false alarms and false alarms is at least the same.

"So this system is ready to be verified on the J-10?"

Although Lu Yuying is not in charge of Project No. 10, he is naturally concerned about the projects of the same research institute.

"Yes, in order to achieve active stability control, the premise is to achieve the integration of flight propulsion, and the most potential in this regard is the J-10 using a three-axis four-redundancy digital fly-by-wire flight control system. On the other hand, single-engine aircraft also have higher safety requirements. ”

In fact, the J-10 itself has achieved the characteristics of all-envelope first-class flight quality and "scruples-free" handling at the aerodynamic level.

What Chang Haonan wants to do is to achieve this at the level of aviation power.

But he had another reason not to say it—

The Su-27 air intake is a bit too simple, and it is likely that some data will not be collected in specific cases......

(End of chapter)