"The turbofan engine is not a high-end engine, but there is a problem with the route we developed, and the turbofan engine is also simple and difficult, and these technical obstacles are not as difficult to overcome as we imagined. The solution I am going to propose now is a relatively simple design, and we have figured out the way of the turbofan engine through this simple design, which is the biggest gain of our engine this time. ”

At the beginning, Yang Hui did not directly say his plan, but first talked about the difficulty of the research and development of this turbofan and the necessity of research and development.

And everyone's reaction did calm down, waiting for Yang Hui to say his final turbofan modification plan.

"We understand that the increase in thrust of the turbofan engine is proportional to the ratio of the internal and external channels, so let's calculate how much thrust is needed for this new machine, and we need to increase the thrust by 0.4 tons according to the maximum thrust of 7.2 tons. In order to achieve our 0.4 tons of thrust increase, the ratio of internal and external channels is not too large, at most about 0.3-0.4. ”

Hearing this channel ratio of about 0.3-0.4, everyone still doesn't understand this, the channel ratio can only explain the ratio of the air flow of the internal and external channels, and the larger the channel ratio, the stronger the push. The channel is smaller than the turbofan, and the whole technology is some difficult and difficult points, where is it so easy to do.

Among so many people, Yang Hui, Director Bai, and Xie Lianfa are specialized in engines, and the rest of them also have a general understanding of the turbojet engines used in the base. The turbofan engine knows the principle, but it is really blind to go deeper, the information in that era is not as smooth as that of later generations, and the country is obsessed with turbojet, so naturally I don't know much about turbofans.

Director Bai, who is an engine, can understand, but he doesn't plan to interrupt Yang Hui now, let Yang Hui continue, maybe according to Yang Hui's idea, it is really possible to let the base engine manufacturing take the lead in the turbofan era.

He didn't speak, but his behavior was unmistakably expressing his support for Yang Hui, and everyone who watched stared at him and wanted to hear his opinion, Director Bai just nodded affirmatively.

Everyone stabilized again, and Yang Hui continued: "The small channel of 0.3 will be much simpler than in R&D and manufacturing, and the most important thing is that we can effectively control the fan diameter." ”

What are the benefits of controlling the fan diameter? The benefits are great: with the diameter controlled, the fan blades can be made shorter, and the blades are shorter, which is a great thing. First of all, it will be much simpler in manufacturing, which is more suitable for the current manufacturing level of the base, and the yield will be higher, so that the cost can also be reduced.

What are the other benefits of controlling the diameter? Yes, if the fan diameter is controlled, the diameter of the engine will also be controlled, which is absolutely necessary for the new machine. Because the rear fuselage of the new machine is not intended to be greatly modified, and the rear fuselage is not made major modifications, then of course, the diameter of the engine cannot be increased too much.

Moving on to the point of controlling the fan diameter, Yang Hui continued to elaborate on the benefits of a small bypass ratio.

"The reason why the turbofan engine is not as good as the turbojet at high altitude is that the air that the fan can inhale at high altitude is reduced, resulting in the reduction of fan efficiency, the larger the channel ratio, the faster the efficiency decreases. But the turbojet will not, so we take a relatively small channel ratio, so the flight performance of the engine will be closer to the turbojet when flying at high altitude. ”

It is recognized that the high-altitude performance of a turbofan engine with a small bypass ratio will be better than that of a large channel ratio. In order to take care of the high-altitude performance, the F119 engine used in the later F22 adopted a small bypass ratio design, and the price was naturally fuel consumption.

There is even more of the former Soviet Union's generation of famous aircraft MIG31 interceptor, the engine used is a turbofan engine, which is logically impossible to fly to an altitude of 30,000 meters, let alone sprint at three times the speed of sound. But the D30F6 turbofan engine used did just that, and the reason was because this guy installed two turbofans with a small bypass ratio.

Speaking of which, it is also understood that the new aircraft uses another reason for the use of small bypass ratio turbofans, the new aircraft is still developed from the Jian-7, a second-generation aircraft that focuses on high-altitude and high-speed performance, and the main role of the new aircraft is to train the second-generation aircraft. Then it is necessary to retain the high-altitude and high-speed performance of the new aircraft.

Although Yang Hui knows that the third-generation aircraft that focuses on low-altitude fighting performance is the mainstream in the future, but now training the Jian-7 is the main thing, otherwise you can train third-generation aircraft pilots with excellent low-altitude dogfighting skills and drive second-generation aircraft, this is certain death. The low-altitude and low-speed performance of the second-generation aircraft is so low, just look at the martyr Wang Wei in the South China Sea collision incident that year, that is, a typical second-generation aircraft to do low-speed flight maneuvers.

(PS These are just an analysis of the low-speed performance of the second-generation aircraft, and there is absolutely no disrespect for the martyr Wang Wei, he is immortal, everyone should remember, don't just remember that Leslie Cheung died on that day, the same day every year is also the memorial day of the martyr Wang Wei.) ）

In order to train second-generation pilots, it is absolutely necessary to retain the high-altitude performance of the new trainer, and Yang Hui went on to elaborate on the various benefits of using turbofans.

"If we make this turbofan with a small bypass ratio, when the time comes to use more titanium alloy materials, then it is entirely possible for the thrust-to-weight ratio of our new machine to reach 7, and at present, if we want to increase the thrust of the turbojet 13 to the thrust required by the new machine, we only use a small bypass ratio turbofan is more realistic, which is a test of our design ability. However, this will not rely too much on manufacturing capacity and material performance. ”

Finally, the manufacturing capacity and material performance have completely dispelled the idea that everyone wants to find other ways to improve the performance of the engine.

Yang Hui said everything he wanted to say, and the four aspects of improvement were also said, although the last turbofan technology is risky, but the harvest is definitely big, once the design of the turbofan engine is broken, then the entire base can be revitalized, this is the magic of an excellent engine, it is not an exaggeration to say that it can turn decay into magic.

Listening to Yang Hui, a young man, say so much, it's time to listen to Director Bai's comments, after all, such a big thing is still for old researchers to be more down-to-earth, this is the disadvantage of being young, hairless on the mouth, and not doing things well This is deeply rooted in the hearts of the people. Yang Hui's biological age in his early twenties is there, and there is no way.

They all looked at Director Bai, but now Director Bai was still thinking about the additional promotion plan that Yang Hui said, and after a long time, he finally thought about it, and raised his head to find that Yang Hui had finished speaking, regardless of the rest, Director Bai applauded heartily.

Since Director Bai applauded, then this Yang Hui's plan was naturally feasible, and everyone who had long been concerned about Director Bai applauded, and for a while, the small room was thunderous.

After the applause was over, Director Bai opened his mouth and planned to say a few words.

"I am personally quite optimistic about this set of improvement measures, according to this improvement plan, it should be the most reliable way for us now, if not, we have to introduce foreign engines. But this is absolutely not possible, and the domestic army will never agree to it. ”

"So my personal opinion is to modify the turbojet 13 according to Comrade Yang Hui's plan, so as not only to ensure domestic orders, but also to make money from the purchase of engines, anyway, now there is a maximum of 600 million US dollars for us to use, plan well, we can still make the engine together."

With the initial design plan of the whole new machine, then it is ready to start making paper information, which tests the production ability of "PPT", and the Republic of Korea, a major country in the universe in the future, is good at this, and the PPT does more, no matter how beautiful it is, but it is useless. It is almost impossible for a small country to make a military fighter, and even the most backbone Swedish fighter has not done much after the Saab 39.