The military-industrial scientific research system of the academic master

Soon after, prototype No. 01 finally appeared in the sight of everyone at the tower.

Through a high-powered telescope, the commander could see that the right fuselage of the aircraft had been deformed, and the tail nozzle of the right engine was also severely damaged.

However, there was no structural damage visible to the naked eye on the air intake section, so it is unlikely that the accident was caused by a bird strike.

"The altitude is 120, the speed is 427, the visual condition of the tower is good, the attitude of the aircraft is stable, but the descent rate and approach speed are slightly faster."

Lin Tingguang used all his strength to pull the control stick and pull the aircraft out of a shallow dive.

When the descent rate and landing speed could not be guaranteed at the last moment, he had to let the thicker rear landing gear land first, even though he might face some risk of stalling.

At this moment, Lin Tingguang only had the runway and his plane left in his entire world, and nothing else.

Even the sound of the tower commander reporting flight data in the headphones gradually became blurred.

At the moment when the plane was about to land with the last few meters in altitude, Lin Tingguang opened the plane's parachute in mid-air.

"squeak--"

The wheels made contact with the runway, sending up a puff of white smoke.

Opening an parachute in the air at the last moment before landing was a trick that the Soviet instructor taught Lin Tingguang when he was learning to fly the Su-27, but he had never tried it on other aircraft before.

Regardless, this risky move brought his landing speed down to a safe level and allowed him to use almost the entire length of the runway.

In the end, the No. 01 prototype came to a halt dozens of meters in front of the already deployed blocking net.

The emergency response brigade, which had been on standby for a long time, also rushed forward. The fire truck began to spray water on the right engine, which was still smoking slightly. The rescue team opened the cockpit cover from the outside and lifted Lin Tingguang out of the cockpit.

"I'm fine, I can walk on my own..." Lin Tingguang took off his flight helmet and tried to stand up, but in the end he was thrown directly onto the stretcher. However, judging from his voice and the intensity of his struggle, he should be fine.

The tower, which had been filled with a heavy atmosphere just now, instantly burst into cheers.

For flight department personnel, saving the aircraft is cause for celebration.

…

News of a dangerous situation during the test flight, which led to the final forced landing of the No. 01 prototype, quickly reached Shengjing.

It happened that the work coordination meeting had just ended, and Yan Zhongcheng said that Chang Haonan would be given two days to think about the final decision.

When the three people heard the news, the expressions on their faces were stagnant.

Especially Yan Zhongcheng, he closed his eyes in pain.

Although there has not yet been a final determination of the cause of the failure, according to the judgment of Yan Liang's test flight commander, the engine should have failed in the air.

And it is not caused by external reasons such as bird collision.

This was undoubtedly a major blow to him and the entire 606 Institute.

A few seconds later, Yan Zhongcheng took a few deep breaths, opened his eyes again, and looked at Chang Haonan next to him.

The latter was also looking at him.

"There shouldn't be two days left for me to think about it slowly."

There was no wavering in Chang Haonan's tone:

"Let's go to Yanliang together."

Yan Zhongcheng nodded slowly.

Such setbacks have not changed the other party's mind, so there is no need to worry about anything anymore.

That night, more than 20 people, including Yan Zhongcheng and Yang Fenghao, took a Y-7 plane and landed at Yanliang Airport.

Prototype No. 01 was towed into the maintenance hangar immediately after landing, and the maintenance staff also completed the ground inspection.

Soon, Li Zhengqi, the head of the flight test center, came to Chang Haonan and others with a ground crew member carrying four thick crutches and two horizontal bars.

"This is Sergeant Major Lin Gang, the most experienced ground service veteran on our side."

In 1996, the soldier's service regulations had not yet been changed. Lin Gang's military rank was the fourth-grade sergeant major, the highest among the thirteen fourth-grade soldiers.

Lin Gang saluted, then turned to Prototype 01 and began to report:

"According to the preliminary inspection conducted so far, visual inspection of the left engine's first-stage compressor revealed 13 pieces of damage to varying degrees, and the tie rod connecting the hydraulic actuator rocker arm of the adjustment plate and the rear adjustment plate was broken at the root of the earring bolt; the engine and air intake The road transition section was misaligned; using a borescope, it was found that the left and right engine splitter rings were torn."

After Lin Gang completed his report, Li Zhengqi added the situation described by the test pilot:

"The pilot reported that the engine malfunctioned during the afterburner shutdown process after exiting the high speed range. There was no obvious air pulsation sound from the engine inlet before the malfunction."

"When the fault occurred, the aircraft's surface speed was relatively high, the M number was near 1.1, and the altitude was greater than 2km and less than 6km. The inlet ramp was involved in the work. When the pilot controlled the throttle to decelerate, the aircraft experienced axial impulse and was forced to push for a short time. Due to the throttle phenomenon, the temperature of the right engine rose sharply at the initial stage of the failure, and there should be a fire phenomenon."

"hiss--"

A gasp came from the crowd.

Such severe engine damage, if not a bird strike, could only be caused by surge.

Simply put, surge refers to the reciprocating air flow caused by the separation of compressor air flow, which produces high or low amplitude oscillations along the axis of the compressor.

By analogy, it is a bit like an engine "coughing", but this kind of cough is extremely contagious. Once surge occurs somewhere in the compressor, it will affect the entire stage or even multiple stages in a short period of time. The blades affect the working condition of the entire compressor and cause irreversible damage to the compressor structure.

And if, like this accident, surge occurs during the afterburning process, the compressor can easily generate negative pressure during the "coughing" process, causing the ultra-high temperature gas in the combustion chamber to reversely flow back, eventually destroying the entire engine. .

And if the pilot's handling of the surge is not reasonable and timely enough, the fuel that has not been fully burned in the combustion chamber will be discharged backward, and spontaneous combustion will occur behind the turbine after encountering high-temperature gas, which may burn the entire aircraft.

Therefore, Lin Tingguang's emergency decision after the accident was almost perfect, and he almost completely preserved the entire failed engine, which was considered a blessing among misfortunes.

After a hasty dinner, the joint power research team devoted themselves to analyzing and sorting out the test flight data.

Among them, people from Institute 606 are responsible for the engine part, while people from Institute 601 are responsible for the intake duct part——

Although judging from the current situation, this accident has no direct relationship with the airway, the rules and regulations are such that we must not let go of any possible loopholes.

For the surge problem, the most important task is naturally to determine the location of the first surge based on test flight data.

This is a job that relies heavily on experience, and Chang Haonan knows that he can't help much.

But he chose to follow Yan Zhongcheng and fly all the way to Yan Liang, so naturally he would not just watch the excitement.

Therefore, he asked his comrades at the Flight Test Institute to obtain the flight status data before and after the surge accident of the No. 01 prototype.

As for the compressor design data of the turbojet 14 engine, thanks to the digital and parametric modeling that had been completed before, I brought it with me when I came from Shengjing.

There may be many factors that induce surge, but there is only one fundamental reason, or the essence of surge, which is the flow separation of the airflow on the back of the compressor blades, and this separation increases with the rotation of the compressor impeller. The high-speed rotation develops to the entire cascade passage.

Yes, it happens to be the flow separation problem of impeller machinery that Chang Haonan has been studying before.

So he decided to try to calculate the unstable working boundary of the engine while the comrades of the joint power research team were looking for the location of the fault.

There are three more updates to be posted in the afternoon