- 27 December 2005
- Reaction score
Some pictures from cjdby.net of China's AL-31F class turbofan, on display at the China Aviation Museum.
overscan said:If its displayed the right way up, then its a Su-27 version (top mounted accessories).
Afterburner arrangement looks rather similar to the AL-31F...
If the A31F cannot be introduced in time, the J-10 will really have to fly with a turbojet 152023-10-03 07:01
The Chinese J-10 was established in 1986, more than a year earlier than the Taihang engine. The reason for this phenomenon was that it was constrained by the idea that the engine was attached to the fighter plane. However, as a result, the engine progress was greatly delayed. As far as the project is concerned, it is a certainty, and the introduction of the Su-27 was even after 1990. Before that, the engine of the J-10 could not have been left unavailable. It was the rumored turbojet 15.
The turbojet 15 started in 1978. At that time, it was rumored that China used a squadron of F-6 to exchange for a MiG-23 from Egypt, and it also had two spare R29-300 turbojet engines. There were many more. Something else. In short, it was China that obtained the very advanced Soviet-style equipment through special channels. After many years, China has once again actually come into contact with Soviet military technology, and I can't help but be amazed. In particular, the R29-300 has a maximum thrust of 12.5 tons, which can be said to have reached the limit of a turbojet engine and has surpassed turbofan engines such as turbofan 6 and turbofan 9. The first time we got such a good thing, how could we not have the idea of imitating it!
Therefore, in the selection of the J-10 engine, the R29 has fully up to standard thrust, simple and reliable technology (this can be proved by its single-engine MiG-23), and other performances are also acceptable, so it is "a matter of course" that the R29 has become a J-10 engine. -10 power system. But even the F-9 used turbofan 6 many years ago, but the next-generation F-10 will use a turbojet engine, which is unacceptable. Moreover, regardless of the simple technology of R29-300, based on the level of China at that time, it will be really impossible to imitate it for a while, so what should I do? Then import it. After all, there are not many prototypes for the early test flight of the J-10, and there are not many engines needed in total.
Just do it, matching the J-10, a full-size metal prototype called the Turbojet 15A was soon sent to Chengdu, ready to be installed on the J-10 prototype for testing, but the plan can't keep up with the changes. With the first batch of Su-27 With the delivery in June 1992, it is a foregone conclusion that China will obtain AL31F engines in batches. Now that there is a better choice, the turbojet 15A version of the J-10 will not be followed.
It now appears that the timely replacement of the AL31F engine is the luck of the J-10, because although the R29-300 has sufficient thrust, it has many shortcomings:
First, the thrust-to-weight ratio is only 6.54, which is still the Russian standard. When converted into the American standard, it is a little more than 5, which means that the total weight of the engine is close to 2500 kg. This will inevitably have a huge impact on the center of gravity distribution and the overall structure of the F-10, and even make it Its lift center moved behind the center of gravity and turned into a longitudinally statically stable aircraft, so the leading test flight with the turbojet 15 lost its meaning.
Second, the size is quite different from the Taihang engine. R29-300 uses a 5-stage low-pressure compressor and a 6-stage high-pressure compressor design, which is completely different in structure from the Taihang engine with 3-stage low-pressure and 9-stage high-pressure, which results in a big difference in appearance between the two. Although the length of the R29-300 engine is only 4991 mm, as a turbojet engine, its diameter is too small. The similar AL21-F3 turbojet engine has a diameter of only 885 mm, while the diameter of the Taihang engine is as high as 1200 mm. The difference is more than 300 mm. It should be known that the diameter of the AL31FN engine is only less than 100 mm larger than that of the Taihang engine. The J-10A had to enlarge the air inlet, which caused the air inlet to be overweight, and had to design the criticized "six ribs" to compensate. Strong, if turbojet 15 is used, how big changes will the F-10A be!
Third, the most important point is that the R29-300 engine's maximum thrust of 12.5 tons is of little practical value to the J-10. The total pressure ratio of R29-300 is 13. The temperature in front of the turbine is only 1147°C, which is too big compared to the AL31F engine's total pressure ratio of 23.8 and the temperature in front of the turbine of 1392°C. Therefore, the maximum thrust of the R29-300 engine of 12.5 tons is likely to be achieved after taking "stimulants"—the Soviet-style oxygen supplement system. At this time, China is already inclined to a more scientific European and American route. Therefore, R29- The 300 engine's maximum thrust of 12.5 tons is actually of little significance to the J-10.
In summary, the turbojet 15 modified from the R29-300 is actually very unsuitable as a test flight engine for the J-10, but because of the lack of choice at the time, it became an alternative, but this alternative allowed the J-10 10 The price paid was still too great, but the flight test results were limited. Without the timely appearance of AL31F, the development process of the J-10 would be more tortuous. Because the R29-300 has long been discontinued, China may have to imitate this already backward turbojet engine, and the development of Taihang engines will also be more tortuous.