Although it is only an improved model, aviation safety is too big for the sky, and the necessary testing process must not be sloppy.

What's more, the utilization rate of this so-called "Spey Change" with new technology is almost more than one-third -

The first prototype 9A-01 modified some irrational designs of the blades and oil supply parts of the high-pressure compressor, replaced it with a new domestic oil pump, bearings and gear set, and integrated the original bearing assembly.

As a result, the number of components is reduced and the surge margin is widened.

By this time, although there were still a lot of modifications, they still belonged to minor repairs to the prototype engine.

Not only has the performance calibration not changed, but the core design of the hot end components has also remained original, so the basic performance has not changed much, except that the dead weight has been reduced by about 75 kg.

But with the second prototype, the 9A-02, which began production at the end of 1997, the changes were quite significant.

In order to test the effectiveness of the new active cooling technology, Chang Haonan specially asked the technicians of the 606 Institute to revise the engine performance calibration.

By improving combustion efficiency and upgrading jet fuel, the pre-turbine temperature was increased by about 50-60°C, to a level close to that of the third-generation turbofan engine.

The design of the aero engine affects the whole body.

For this reason, the compressor of the second prototype engine was also modified, and the active control technology of blade separation flow developed during the development of the turbofan 10 was adopted on the blades of the 9-12 stage high-pressure compressor, which increased the total pressure ratio of the compressor to about 22-23.

However, because the research and development of the manufacturing process still needs time, the electrolytic machining, electron beam welding, precision forging, precision casting and other technologies used in the production and manufacturing of this engine are still at the previous level.

In particular, the machining of air film holes in turbines and combustion chamber walls.

Compared with a dozen accurate round holes, the dustpan-shaped holes with forward inclination angles developed by Chang Haonan are quite unfriendly to the EDM technology developed by Factory 410.

Not only does the machining of each hole require several more processes than that of the Turbojet 14, but the subsequent grinding and quality inspection also require additional steps.

The yield rate is also much lower.

In short, although Chang Haonan was eager to start testing this engine that used a lot of turbofan 10 technology the day after the map was released, it still took more than two months for the 410 factory to produce the 9A-02 machine even if it set aside a special production line and produced in three shifts 24 hours a day.

……

At the door of the engine assembly workshop of the 410 factory, Chang Haonan, Zhong Shihong and Zhang Zhenhua stood side by side, watching the engine that had finally completed the inspection of the whole machine of the factory being slowly installed on the specially designed engine stand.

Zhang Zhenhua took two steps forward, reached out and gently patted twice on the tail nozzle of the mid-air engine.

Shengjing, mid-January morning.

The temperature is about -20°C.

The tail spout of the metal was cold to the bone, and Zhang Zhenhua, who was not mentally prepared, was frozen.

However, he still couldn't hold back, and gently stroked the oil line exposed on the outside of the engine case.

The intoxicated expression is slightly perverted.

It wasn't until the engine was secured by the hoisting group and began to be packed in cargo boxes that he reluctantly returned it.

"Spey, after more than 20 years of localization, we have finally built a 100% domestic engine......"

With the bursts of white mist in front of him, Zhang Zhenhua said with emotion.

In order to speed up production, about a quarter of the components of the previous 9A-01 still used British imports directly.

But this second prototype, due to the huge improvements in all aspects, the original British parts can no longer adapt to its working condition.

Therefore, all components are newly produced in the country.

In this process, the 410 factory also verified the application of several key new manufacturing technologies such as metal spraying, vacuum heat treatment, trajectory welding, vacuum brazing, and CNC pipe bending, laying the foundation for the next turbofan 10 manufacturing.

"yes, it's a pity it's a little too late......"

Zhong Shihong took out a ballpoint pen and responded while signing his name on the factory list:

"After the introduction of Spey, it has been swaying for more than ten years, and now the domestic model is made, even if the performance is better than the original goods, the prospects are relatively limited......

The introduction of Spey also hides a period of love-hate between Factory 410 and Factory 430.

The former insisted on continuing to work on turbofan 6, while the latter thought that it should start with Spey.

If I have to say it, it ended up in a lose-lose situation.

By now, it is not clear who is who.

Fortunately, for Zhong Shihong and Zhang Zhenhua's generation, there are not many relevant memories.

The smell of gunpowder between the two units has gradually disappeared with the advancement of the turbofan 10 project and the deepening of R&D collaboration.

Contradictions, fundamentally speaking, come from competition in resource allocation.

Now Chang Haonan has almost expanded the scale of Huaxia Aviation Development Industry by an order of magnitude, and the difficulty of dividing the cake has naturally decreased a lot.

Despite this, after noticing that the topic between the two people was gradually moving closer to the direction of the old past, he quickly pulled away from the topic:

"It's useless to talk about the past."

Chang Haonan also took the pen from Zhong Shihong as he spoke, and signed his name.

The production of the turbofan 9A prototype was nominally as a technical verification machine for the turbofan 10, and naturally he was indispensable for the signature of the chief designer.

"No matter how you say it, the improved J-7 must also have a demand for dozens or hundreds of aircraft, and the turbofan 9A can still make a difference in this regard."

"It's just a pity that the Spey Airlines was refueled that year, and now the QC130 refueled by the turbojet 14 has entered the design finalization stage, and the Navy should not accept another gas turbine with similar power......"

After the factory formalities were signed, the staff quickly loaded the neatly packed engine box onto a special Mercedes-Benz semi-trailer.

This car is probably the only 100% imported product in the entire turbofan 100 project.

The main reason is that everyone is really lacking in skills, and they really don't have the time to build a special engine transporter.

The completed engines will be transported by the vehicle to Beiling Airport, and then transported by an Il-76 transport aircraft to the 624 Institute for the necessary ground testing.

"Mr. Chang, what do you think the actual performance of this engine can reach?"

As the head of the production department, Zhang Zhenhua has little experience in the field of engine design, so he is not clear about the specific effect of these upgrades on the turbofan 9A.

"Don't expect too much......"

Chang Haonan shook his head, returned the pen in his hand to Zhong Shihong, and continued to explain:

"The design level of the Spey engine itself is not good, and I spent a lot of time adjusting the data of the compressor and the combustion chamber, but the matching degree is always average."

"After all, it's an improved model, and it's impossible to redesign a core machine with a lot of effort, so it's just a matter of that."

There was a hint of dissatisfaction with the British in his words.

Of course, the two people next to him will not have any objections.

After all, Mr. Chang's ability is obvious to all, and he is indeed qualified to be evaluated.

"In addition, because the multi-arc ion plating equipment in the factory was not in place at the time of the blade production, the new coating technology was not used for the hot-end parts, and the increase in the temperature before the turbine was relatively limited."

Of course, on the other hand, the pre-turbine temperature of the Spey MK202 itself is not low, and it is true that the British can design such a mediocre engine with such a high pre-turbine temperature...... Tsk tsk. ”

At this time, Zhang Zhenhua and Zhong Shihong must be difficult to answer.

"That'...... How much can some typical paper performance be improved? ”

"It's more specific, I don't know until I've done bench tests."

At this time, a Jetta King stopped in front of the three of them.

Naturally, it is Zhu Yadan who drives.

Chang Haonan opened the right rear side door, turned back to the two and continued:

"However, according to the performance calibration I made, the sea-level thrust can probably be increased to 10,000kg, and the total weight of the engine, according to the national standard, should not be higher than 1,750kg."

After finishing speaking, he got into the car and signaled that the convoy could leave.

Only two people were left messy in the wind.

"It's still called 'don't expect too much'?"

Zhang Zhenhua looked at Zhong Shihong next to him with a stiff movement.

You must know that the sea level afterburner thrust of Spey MK202 is 9300kg, the national standard weight is as high as 1842kg, and the thrust-to-weight ratio is only 5.05.

The turbofan 9A directly increased the thrust-to-weight ratio of the engine by nearly 15%!

"You know, Mr. Chang has always been very demanding on the project."

Zhong Shihong helped the cotton hat he was wearing on his head.

He actually felt a little outrageous, but in front of Zhang Zhenhua, he still maintained his demeanor and did not show obvious surprises:

"Anyway, I'm already looking forward to the performance of the Turbofan 10......"

(End of chapter)