Chapter 1044: The rear fuselage has a large amount of modification

Thinking of history, Qin Guan has a sigh of emotion. In history, Jianba and RB199 passed by.
Back then, due to its low technical level and no advanced aircraft, Han was forced to develop a double-engined J-8 interceptor on the basis of the J-7. However, the technical level was still very low and there was not much advantage.
In the 1980s, the West opened its doors, and when I went to the West, I knew how backward it was. Therefore, at this time, Han began to move closer to the West, hoping to develop itself by introducing Western technology. s plane.
They also took a fancy to the RB199. The West promoted the use of RB199 to replace the J-7 engine, and the 6601 Institute also plans to use RB199 to replace the J-8 engine.
However, at this moment, the JH-7 project suddenly leaked out. When the West heard that Han was developing such a fighter-bomber, they immediately became cautious.
It can also be seen from this point that the West will not sincerely hope that Han will be strong. Even if Han is equipped with advanced fighter jets, it will not allow Han to possess bombers. After all, the attack capability of bombers may pose a threat to the West.
The West believed that Han purchased the RB199 for the JH-7, which was embarrassing. The J-8 was a secret project at the time. The West did not know that all the misery of 6601 was unspeakable. In the end, the West closed the door and the J-8 was not. Expected to change the engine.
Now, the situation has changed a lot. After the introduction of the Tomcat fighter, the J-8 project is no longer confidential and has become a foreign arms sales project. In this case, the J-8 is replaced with a world-class engine. It is normal to push it to the international market.
After the 6601 was responsible for its own profits and losses, it was a painful experience. Not only did the F-8-2 change the telex operation, it also completed the matching of the new engine.
Now, Qin Guan stood on the rear fuselage of the J-8 and could see that there had been obvious changes.
In the previous J-8, the ejector tail cover was used.
Equipped with afterburner jet engines, mankind has entered the era of supersonic flight. Due to the net pressure of the aircraft during supersonic flight, the exhaust pressure of the engine increases, resulting in the nozzle drop pressure ratio (the ratio of the pressure of the engine exhaust flow at the nozzle section to the ambient pressure) also increases, reaching 15-20 , Even higher.
At this time, the exhaust flow at the outlet of the nozzle is working under extremely under-expansion conditions, and the thrust loss is as high as tens of percent! In order to "recover" this part of the thrust, the engine designers are working at the outlet of the main nozzle Adding an outer tube or ejector hood is equivalent to adding a tube skirt to the outside of the pleated skirt, which is the ejection nozzle.
The ejector nozzle allows the engine to add an ejector exit section behind the original main nozzle constricted end, that is, behind the throttle section. In this way, the main airflow introduces one or several new flows before leaving the engine or aircraft, causing the total exhaust flow to increase. Moreover, the nozzle of this structure allows the airflow to continue to expand, further increasing the exhaust velocity and increasing the thrust of the engine.
However, this is all theoretical, and even theoretically, there is no specific formula to describe it. Most of it comes from experiments on airplanes.
The tail hood of the ejector used by the J-8 is not only very heavy, but actually can't play the role of the ejector tail hood, it will only lose thrust in vain.
This design was all the rage in the 1940s and 1950s, but in fact, except for very individual conditions, the performance status of the ejector tail cover cannot be calculated at all, and can only be estimated by reluctantly relying on test results.
The previous J-8 was actually designed to cross the river by touching the stones, almost from the J-7, which naturally has many flaws.
Now, after the RB199 engine is installed, this cumbersome ejector tail cover has been removed, because the third-generation engines all carry their own tail nozzles. This type of tail nozzle is more advanced and belongs to the retractable type. Nozzle.
The retractable nozzle can be regarded as a "double pleated skirt" with two small ends connected together, which makes the nozzle flow path first shrink and then expand, allowing the airflow to reach the speed of sound at the throat and further accelerate to become super Sonic flow. Since this nozzle is adjustable at the end section (throat) of the contraction section and the exit section (exhaust port) of the expansion section, it has both good sub-transonic performance and excellent supersonic performance.
The J-8 finally removed the tail cover of the ejector, which made Qin Guan feel happy for a while. Of course he knew that this thing must be removed, but later generations will be in the 1990s.
After all, the expected benefits of this design are actually the result of the designer's past experience and subjective speculation, and lack rigorous scientific and engineering basis. Later, Xiong Guo did a lot of modification and comparative flight tests of the old models. The test involving the tail cover of the ejector proved that this thing was useless.
Therefore, in the later generations in the 1990s, with the easing of relations with Xiong State, Xiong State experts were used in the form of technical assistance to modify the tail design of the J-8 series.
In this way, the tail of the aircraft has been greatly changed, except for the tail nozzle, which is the tail tip that has been criticized.
It can be said that with this transformation, the rear fuselage of the J-8 has been greatly changed. As for the front, there is not much change.
The nose is still the same, the cockpit has a three-piece windshield, and the back is high. The pilot does not have any rearward vision. It is still like an authentic second-generation aircraft.
"President Qin, how are we changing this aircraft?" Mr. Gu asked Qin Guan.
Qin nodded his opinion: "The subsequent modifications are not bad. If the engine and the air intake can be matched well, the performance should be greatly improved."
As soon as he said this, Mr. Gu suddenly nodded his head again and again: "Yes, it has a reborn performance improvement. Our aircraft will definitely be able to defeat the J-11 and get an order from the Air Force."
Hearing Mr. Gu's words, Qin Guan couldn't help but frowned.
For 6601, as the big brother developed by the Han Chinese military aircraft, of course they can’t tolerate the embarrassment that they have no competitive products. Now that they are working so hard to improve their fighters, they have only one idea, that is, to put their own Fighter aircraft equip the air force.
But is this possible?
The fighter aircraft equipped by the Air Force must be independently produced. The landing gear problem is not big, but the engine problem is big! If the engine of this aircraft needs to be imported, it will be choked by the Western world at any time.
"What? President Qin, do you still think my aircraft can't meet the needs of the Air Force?" President Gu couldn't help but ask when he saw Qin Guan's appearance.