Changing the engine, is it easy to change?

It's definitely not that simple, changing the engine is definitely a big project that hurts the muscles and bones!

First of all, the thickness of the engine, this must be accurate to the millimeter, as long as the thickness is different, it will bring a lot of problems, this point has appeared on the F-16, the F-16 was originally used the F100 engine, because it is a turbofan engine, so it is thicker, and later, in order to export, it was decided to change to the J79 engine, which is a turbojet engine, relatively thin, as a result, directly stuffed into the rear fuselage, artificially wrapped in a circle of brass outside, which led to additional weight gain, This kind of engine seriously dragged down the performance of the fighter, the thrust decreased, the fuel consumption rate increased, and the additional dead weight was added, so it was not sold in the end.

In fact, the design of the J-10 is still carried out in accordance with the scheduled turbojet 15, after all, this is what can be done in China now, and Song Lao of course knows that the development of the turbofan 10 is very difficult, so although he wants the turbofan, it is still designed according to the turbojet 15.

Compared with these two, the AL-31F engine used by the Su-27 fighter, although it is a turbofan engine, theoretically has a lower fuel consumption rate, but its cross-sectional area is larger than that of the turbojet 15, so that the rear fuselage must be thickened, and after being thickened, the drag increases, which may offset the increase in thrust.

Even, it will be worse! After all, due to the different sizes of the engines, the fuel tanks in the rear fuselage may also be occupied, so that the range cannot be guaranteed.

In this way, the rear fuselage had to be redesigned, which was almost the same as redesigning, not only the rear fuselage, but also the problem of the air intake.

Different engines, the need for air intake flow is different, turbofan engine with air intake flow is definitely much larger than the turbojet, then, their own front air intake, also have to be modified, now is similar to the F-16 oval air intake, in order to increase the air intake, I am afraid to have to enlarge the oval into a rectangle, which will also lead to the original design of the strength is not enough.

Increasing the area of the air intake, further increasing the drag, it is possible to squeeze the advantages of the turbofan engine even more, besides, this fighter must have outstanding high-speed interception capabilities, the overall performance of the turbojet 15, in fact, is still good.

If from a layman's point of view, the engine is not powerful, I will change to a large engine, in fact, this is not the case at all, this is like the super seven project that Tu Lao they engaged in, it was originally intended to be improved on the fuselage of the J-7, and the F404 engine was stuffed into it, but as a result, after several twists and turns, it became a completely new project, and I can no longer see the shadow of the J-7, directly change the engine, where is it so easy!

Look at Lao Lu again, the design of the strong six, is planned to use the turbofan six engine, later, before the strong six project was launched, the leader once talked to Lao Lu, asked him if he could replace his own inventory of Spey engine, was immediately rejected by Lao Lu, how can this be? After the design is out, if you change the engine, it will definitely be playing the piano randomly.

Now, the J-10 has entered the process of detailed research and development, and it will soon be able to freeze the drawings and start manufacturing the first prototype, and now if it is like what Qin Feng said, the engine of the Su-27 fighter is exchanged, it is almost equivalent to being pushed down and restarted, the rear fuselage must be completely redesigned, the air intake tract must be redesigned, and only the wing and nose can still be retained.

If it is delayed for too long, this project may face setbacks, just like the J-9 project, even if it is the J-7 3 project, isn't it because the delay is too long, which eventually leads to backward technology, and then the Air Force does not want the dilemma?

Song Lao was deeply worried about this, Qin Feng was an excellent test pilot and had a lot of knowledge, but he didn't know all the details of aircraft design.

Song Lao was thinking about this question when he saw that General Lin was already energetic: "Really? That's right, the Su-27 is a heavy fighter, and its engine is also aimed at the F100 of the Americans, and the advantage of the Soviets' equipment is that it is strong and durable, anyway, our turbojet 15 is also Soviet, so let's just go directly to the Su-27 engine. ”

What does the engine mean to the research and development of the fighter, the people present are clear in their hearts, over the years, the miscarriage of one project after another, in essence, is because there is no engine, J-8 can succeed, there are many factors, the most important of which is that the engine it uses, is two J-7 engines, so that there will be no heart disease problems, the success of J-7 is also because there are two qualified Spey engines.

The core machine of this project is actually an imitation of CFM56, which is an engine for civil aviation, which is jointly developed by the French and Americans, and the core engine of this engine is the same as the core engine of the F110 engine equipped in F16, which can significantly reduce the difficulty of research and development, but even so, if you want to get the turbofan ten out, it is conservatively estimated that it will take ten years, and the Air Force can't afford to wait.

Hearing General Lin's words, Song Lao's heart was full of mixed feelings, General Lin, a layman, actually recommended changing the engine, which is quite difficult for his own side, but since General Lin said so, it also proves another thing, that is, although the Air Force is now buying fighters from abroad, the Air Force has not given up the domestic project, and has not given up the No. 10 project.

What Song Lao is most worried about is that the Air Force uses all the funds for foreign military purchases, in this case, the research and development of the Jian-10 will be dangerous without support.

After all, no matter how good the outside is, it is also outside, only if you develop it yourself, that is your own thing! General Lin said that the Su-27 engine was used to change the equipment, which was naturally to let the Jian-10 project go on as soon as possible, and he should be relieved when he heard this.

"General Lin, we're talking about the introduction now, right? As for what engines our project No. 10 will use, at least wait until the Su-27 has a chance to buy it back, and then talk about it, right? Song Lao said.

It's too early to discuss the J-10 now, everything is empty talk, the purchase of the Su-27 will have a great deal of uncertainty, and when the Su-27 can be purchased back, let's discuss the issue of the engine.

Besides, the AL31F is a double engine on the Su-27, and its own J-10 is a single engine, a double engine for a single engine, a receiver or something, it must need to be changed, these, you have to cooperate with others to do it, are people willing to modify it?

This, the uncertainty is too great.