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According to Paul Schwartz, China is "still heavily reliant" on Russian turbofan engines:

Beijing is still heavily reliant on Russian aircraft engines, however, due to the great difficulty of reverse engineering advanced turbofan engines. Thus, additional purchases in this area remain likely as well. [...] The purchase of additional Russian turbofan engines will allow China to continue building out its military transport fleet, while keeping its J-10 fighters and H-6K medium-range bombers operational. The J-10 is an important component of China’s air force, while the H-6K allows China to conduct cruise missile strikes out to the second island chain.

Source: Paul N. Schwartz, The changing nature and implications of Russian military transfers to China, CSIS, June 21, 2021.


Why is China "still heavily reliant" on Russian turbofan engines? Why is reverse-engineering advanced turbofan engines so difficult? Is it due to lack of expertise on

  1. materials and metallurgy?

  2. precision machining technology?

  3. control systems?

  4. electronics?

China is an industrial powerhouse. Naively, one would expect China to be ahead of Russia on all fronts, but that is not the case, which piqued my curiosity. I know that, in recent years, COMAC faced difficulties but it is alleged that those were of a structural nature, not quite turbofan-related.


Related:

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Sometimes it's cheaper and easier to simply buy the complicated bit from a friend than bother producing it in house. The Chinese air force is still heavily reliant on Russian aircraft and engines tend to burn out faster than airframes so the need to replace them rapidly vs replacing airframes tends to be much higher. All of the air superiority aircraft that China operates are either Russian built or Russian designed so why not use Russian engines if they are willing to sell them at a reasonable price?

Forget about designing new engines, even building existing designs takes high quality metallurgy and manufacturing techniques that China may simply have not mastered yet, or again, is unwilling to invest in mastering if Russia is willing to be a partner.

This article provides a decent overview of the situation while this article indicates that they are indeed beginning to build domestic engines for their fighters and there seems to be continuing development. Keep in mind this only begins to put china in league with production of jets like the F-22 that the US has been building for the better part of 25 years.

Its also worth noting that the ability to build something and the ability to understand something are very much not the same thing and there is skill required on both fronts to master something. Even if China were able to spool up the ability to build Russian designed engines they would also need to spin up the academic side of the equation to advance any designs they were building and avoid being stuck with out dated designs.


Side Note: It is not uncommon through out history to source parts and materials from other places for wartime equipment, perhaps the most wild example is that the SR-71 Blackbird used during the cold war to spy on Russia was built mostly out of Russian Titanium...

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The short answer is: Designing good and/or efficient jet engines is incredibly difficult, and the Chinese do not have the capability to do so.

Modern jet engines are a marvel of engineering. Some even say that these are the most complicated machines ever built by mankind (on the other hand, some people say that about computers...), see also why do new jet engines cost billions to design. These are very complicated machines, which have to withstand extreme pressures and extreme temperatures. To make them more efficient, you typically have to further increase engine temperatures and pressures. All of this is very design intensive. There are only a couple of high-tech companies which can design those aircraft engines, and the Chinese are apparently actively trying to espionage these (note that they only tried to spy on companies which were involved in designing the engines). I even heard one story, in which an Airbus A320 "vanished" in China to reverse engineer the engines. Only after diplomatic pressure was this aircraft released. However this might be a tale, I cannot find a source for this story.

Therefore long story short, the Chinese simply do not possess the capability to design these engines. And this is due to the challenges of the engines such as metallurgy, aerodynamics, vibration, integration and so forth and so on which is just very hard to master. Western and Russian design companies themselves built these capability over a long time and are typically very high-tech companies such as GE Aviation, Rolls Royce and so forth and so on.

P.S: Some people view Russian engines as inferior to western counterparts though that might not always be correct (How do contemporary Russian jet engines compare to western ones)

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  • $\begingroup$ I would guess that the A320 vanishing in China is probably a tall tale unless this was decades ago. China has hundreds upon hundreds of A320s (as well as 737s, which use the same engines) in the fleets of its own airlines and even has a factory that builds A320s. It would have no need at all to steal one in order to reverse engineer the engines. As far as the link at the end, that seems to mostly be comparing Soviet-era designs, which really doesn't say much at all about the state of things 30 years later. $\endgroup$
    – reirab
    Mar 21 at 19:07
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The most likely reason is that the Chinese do not have the technology to be able to duplicate what they see. Being able to measure every dimension of a fan-blade only gets you half-way towards making one of your own - the metallurgical processes are extremely complex not to mention difficult.

Designing a new engine based on an existing design is easy in comparison, but specifying any part to be a little bigger/better/stronger than a part that you cannot even make is pointless.

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According to Abraham Mahshie, the cause of such dependence is the lack of tacit knowledge:

China is still lagging because Russia withheld advanced secrets. China’s struggle in this area isn’t due to a lack of resources devoted to the effort but a lack of domestic expertise, he said.

Many of China’s scientists, engineers, designers, and production managers are in their late 20s and early 30s, and they lack the know-how that comes from apprenticeship programs and decades of specialized experience. To make up for that, China has contracted Russian specialists to work inside Chinese factories.

However, “This isn’t a ‘throw money at the problem’ solution,” he said.

“What they still have yet to understand is, modern aviation engines, particularly supercruise fighter engines, are more art than science,” Markov explained.

Engine workers at producers such as Rolls-Royce, Pratt & Whitney, and General Electric have “tacit knowledge” that the Chinese are still lacking, he added.

“There’s a lot of phenomenology that takes place in an engine that we still do not … understand … with our qualitative computing technology,” Markov explained. “But there’s a guy named Joe who works at Cincinnati Milacron, who’s been working that thing for 30 years, [who] just knows, through experimentation, time, and experience, that you do this thing to make the engine get this outcome. And that’s the part where China just doesn’t have that capability yet.”

Source: Abraham Mahshie, Dependence on Russian aircraft engines could prompt China to ‘fix their … problem’, Air Force Magazine, May 19, 2022.


Bold is mine.

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