Why Is It So Hard for China to Develop a Jet Engine?
China is the world's manufacturing hub. But can it produce jet engines for aviation? After many years of development, the first Chinese airliner finally entered into service in 2022: the Comac C919. However, the Comac was almost entirely constructed using Western technology, engines included.
For many, this move might seem obvious: build a plane using Western technology, learn from it, and make the next using your own. This is of course the case. China knew it was far behind with jet engines, and the only reasonable way to join the race was to begin by learning from Western products. Needless to say, this strategy was not invented in China. It has been used by almost all countries during their developing stage (in the 1950s, “Made in Japan” was considered the cheap copy).
But, even if they do get engines to learn from. Can they manage to make their own? It's not that easy. Let's start from the beginning.
The West
The first jet engine was built in 1937 by British engineer Frank Whittle, officer at the Royal Air Force (RAF). Germany had been working on these engines in parallel to the UK, and released their own design in 1939.
I am talking about jet engines here, not piston engines, which were the norm during World War II. The UK and Germany spent most of World War II refining their already mature piston engine and were not able to introduce jet planes until very late into the conflict. Germany was the first to do so in 1944 with their Messerschmitt Me 262. But they made too few, too late, and with many engine reliability issues. The British Spitfire was a slower plane than the Me 262, but far more reliable thanks to its excellent Rollys-Royce piston engine.
The United States did not have jet engines in the 1940s. But their decision to take part in World War II enabled them to catch-up quickly thanks to the Tizard Mission. In this mission, the UK agreed to share all research and development secrets related to military technologies in exchange for US support in the war. This included jet engines, as well as rocket science and radar (also a British invention).
This exchange ended up being a success. The allies won the war, and the United States closed the gap with Europe in key technologies. The first jet engine locally produced in the United States was the General Electric I-A, in 1941, and it was almost entirely based on Frank White's engine from the UK.
The Soviet Union and China
Despite their efforts, the Soviet Union did not manage to make a viable jet engine by themselves. To fix that, at the end of World War II, they sent a delegation to the UK to ask if they could purchase a few Rolls-Royce jet engines, something that the UK agreed to as a gesture of goodwill. The Soviets quickly reversed engineered the engine and turned it into a local version, the VK-1. They got additional help from all the seized material and workforce from Germany after their capitulation (to be fair, Western countries did the same).
Rolls-Royce was outraged by their move, and the UK government ended up recognizing that the sale had not been a good idea.
After the Korean War in the 1950s, the Soviet Union shared with China the RD-500 engine, an unsuccessful copy of the Rolls-Royce that they got from the UK. By that time, China did not have the resources and engineering skills to make much out of it, so they continued to rely on Soviet expertise for a long time. Even today, many Chengdu J-20 (the most advanced jet fighter in China) are equipped with Russian AL-31F engines, while others use the WS-10 Chinese engines.
Unlike the West, China and the Soviet Union did not benefit from sustained and peaceful growth after World War II. The collapse of the Soviet Union and events such as the Cultural Revolution paralyzed these countries for decades. Therefore, even if all countries mentioned here had roughly the same start (1940-50s), only the West was able to continue with a steady development.
Reliability
The Chinese WS-10 engine suffers from serious reliability issues, especially the first releases. While it's hard to give concrete numbers, at their best, the latest WS-10 engines have a service life of about 1,500 hours. Western engines like the F135 quadruple this value, reaching about 6,000 hours.
The new jet engine model from China, the WS-15, is promoted by mainstream media as an engineering marvel, but reliability issues remain and are highlighted even by outlets such as the South China Morning Post.
Being military applications, concrete numbers on failure rates are generally not available to the public. One thing is certain through, neither the West, nor Russia or China, have shown doubts on the superior reliability of Western engines. The question is not whether Western engines are better or worse than Chinese ones; the question is whether Chinese engines such as the new WS-15 can be just as good as Western ones. There is actually a way to deduce this easily: commercial aviation.
Commercial aviation: the pro league
Governments and military agencies can keep their numbers on military engines secret. Airlines can't. If they want to be certified, strict international regulations require them to disclose all design parameters, maintenance procedures, accident databases, etc. Adding on to that, the public opinion has a much higher sensitivity to accidents in commercial aviation than in military ones.
If China's jet engine industry was on par with the West, they would have obviously used it for the Comac C919. But China had no doubt that the Comac had to have Western engines, for which the LEAP-1C engine was chosen, made by CFM, a joint venture between French and US companies. Chinese airlines have an extremely low accident record (even lower than the West), so using highly reliable Western engines was a wise decision to not undermine their reputation.
Even if China accepted Western engines, they began a parallel program on a local commercial engine, the CJ-1000A. Initially planned to deliver its first prototype in 2020 and perhaps be used for some of the Comacs, the current best estimate is 2030, and there seems to be less hope that it will ever go into a Comac.
The delay in the CJ-1000A means that, by the time it's ready, Western competitors might already be in another league. This is what is happening now with the new Western concept for commercial aviation, the CFM RISE, expected to improve efficiency by 20% and be fully compatible with sustainable aviation fuels.
When it comes to closing the gap in industries like the automotive one, China had a different approach: skip internal combustion engines, and start earlier than the West with electric motors. This was an excellent decision. However, China did not have that option in aviation. So far, there is no direct alternative to jet engines. Hydrogen and electric planes are of course being researched (mainly by Airbus), but these have many many more challenges than cars and don't seem to be economically viable.
Engine blades
So, what exactly is so hard about engines? Mainly the blades.
In the high pressure section of the engine, each blade is exposed to temperatures over 1600°C (2900F) and forces between 10-30 tonnes (22,000-66,000 lbs) during thousands of hours. To visualize this, a single turbine blade should be able to hold the weight of three African elephants for about a year, after which micro-carks or small deformations could be expected.
Blades are made of titanium alloys and nickel superalloys cast into a monocrystal. Monocrystals – a single crystal, a single grain – are very difficult to produce. Regular casting produces materials with an amorphous internal structure made up of millions of small grains, all of which interact with each other under load. In a monocrystal, the absence of grain boundaries make it much more resistant and predictable.
Once the monocrystal is cast, precision tooling shapes the blade to extremely high accuracy, and electric drills make narrow internal channels for cooling them during operation. Apart from the cooling channels, the blades coated with Thermal Barrier Coatings (TBCs) made of low conductivity ceramics that protect them from the engine heat. Accurate application of the TBCs is one of the main challenges of the design.
The nickel superalloys, the monocrystals, and the TBDs are something that China can probably already produce in a lab. However, they cannot make it affordably in mass production and ensure that every single blade has the exact same specs. Again, if one fails, the entire engine fails. This is where the famous “know-how” comes in. The West accumulates decades of research and experimentation in this area, which provides a huge database where the reason for every single design parameter is known and documented.
Material science is far from easy. It’s not enough to know the composition of an alloy. You need to know the exact heating and cooling cycle for the casting (different heats lead to different internal structures), the most suitable casting materials, how to maintain stability during production... Each one of these steps has a dedicated team of experts behind.
Another problem with engines is that, once you think that you made a good design, you need to test it. What do you do then, run the blade for a year and come back to work after that to see if it cracked? Yes, that’s pretty much it. Development, testing and verification take a long time here. In some products, one can do what is known as “accelerated lifetime tests”, which means that you stress the materials to much tougher conditions than what they will actually see, replicating the same stress in a shorter time. The problem is that engine blades are already running at extreme environments in normal operation.
Fuel efficiency
Fuel is one of the largest running costs for airlines, so they welcome any improvement in fuel efficiency from jet engine manufacturers. For example, the CFM LEAP boasted a 15% higher efficiency compared to previous generations, a very attractive improvement for any airline.
Fuel cost is only expected to rise due to environmental aspects. For example, European regulators have placed requirements to increase the use of expensive Sustainable Aviation Fuels (SAF) to 70% by 2050. Airlines such as Lufthansa have already added an “environmental cost” to their European tickets of up to 72 additional euros.
This means that, if an airline is to consider buying a Chinese CJ-1000A engine, they will benchmark it against Western engines, and if these have just slightly better efficiency, that difference will be important. It’s not enough to make a highly reliable engine feasible for mass production. It has to be efficient as well.
A long road to success
China will most likely succeed in making a high quality jet engine for commercial aviation. The CJ-1000A will be delayed, but the next prototype will come closer, and so forth. However, this will only happen if the Chinese economy keeps growing steadily, something that should not be taken for granted. The aging population, high debt levels, and unstable real estate market could induce negative side-effects in a country that still has many areas to develop.
The recent trade war with the US is also worrying for China, since they now see that there is a significant part of the US population that is willing to suffer a potential recession if this one affects China more than the US.
Closing technology gaps is difficult, but not impossible. An encouraging example would be chip manufacturing. So far, the US has been unable to match the transistor size and density that TSMC in Taiwan can make. But the constant inflow of resources that Intel has poured in is now closing the gap, and government actions such as the recent move by the Trump administration to move TSMCs production to the US will bring even more know-how from Taiwan.
If China continues growing, it will surely join the elite team of jet engine manufacturers.