Recently, a major news has erupted in the aviation circle. Many netizens said that our variable cycle engine has achieved "nuclear explosion-level" data: thrust has increased by 47%, and fuel consumption has dropped by 37.5%. Some people may ask, isn't it just an engine? Is it really that big of a deal? But I want to tell you all that you're all wrong because this is not a variable cycle engine at all, but rather a "variable mode engine" that China's scientific research units have developed, which is completely different from what the Americans are doing with variable cycle engines, clearly more superior.

Don't think these two numbers are abstract. If installed on a fighter jet, the J-15's combat radius with its own fuel can reach over 2000 kilometers, which is half more than now! Even more impressive is that if the new generation of fighter jets have reasonable designs, such as the J-36 solving the thermal barrier problem, the speed could reach 4 times the speed of sound. Remember, the US's most advanced SR-71 Blackbird only reached 3.35 times the speed of sound. What secrets does this operation hide? We can imagine.

First, look at the hard data: the dual breakthrough of thrust and fuel consumption will directly transform the fighter jet.

Let's find a reference point. The current J-20 uses the turbofan engine, the WS-10C, with a thrust of 151.9 kilonewtons, which is already top-tier. However, when the test data of the new engine came out, everyone was shocked: specific thrust increased by 47%! Calculating this way, the afterburning thrust can reach 213 kilonewtons, and during previous bench tests, it even reached the threshold of 250 kilonewtons, and it's definitely stable above 200 kilonewtons.

What's the use of higher thrust? Simply put, a fighter jet equipped with it can take off faster, climb higher, and maneuverability is maximized. Even if it carries a full load of missiles, it can still maneuver flexibly. More importantly, fuel consumption has dropped by 37.5%, which is revolutionary. Now, the J-15's internal fuel combat radius is about 1500 kilometers, and with the new engine, it can go over 2000 kilometers, and the range is estimated to increase by 50% conservatively.

What does this mean? In the future, our fighter jets won't need to frequently refuel in the air, allowing them to patrol widely in the Indo-Pacific region, changing the way military deployments are made — places that were previously out of reach can now be reached with a step, and the deterrence power is no joke.

Then dig into the technology: reaching 4 times the speed of sound, and hiding a "combination password".

Just looking at thrust and fuel consumption isn't enough. The core engine's speed domain diagram reveals a bigger ambition. To achieve extreme supersonic speeds! Conventional turbine engines can only fly up to 2.7 times the speed of sound, and the J-58 engine of the US Blackbird reaches a maximum of 3.35 times the speed of sound. While our new engine's performance envelope approaches 4 times the speed of sound, which aligns with the previous reports in the South China Morning Post about China's M4-level engine.

However, there's a key issue here: to sustain flying above 3 times the speed of sound, you need a turbine-based combined cycle technology. Simply put, it's using a turbine engine at low speeds and switching to a ramjet engine as the speed increases, with the two "engines" seamlessly connected.

The variable mode engine we have now is likely to integrate a ramjet mode to secure 4 times the speed of sound. Achieving this performance also involves a core indicator breakthrough. The temperature before the turbine is estimated to be over 2200K. This is like equipping the engine with a "super high-temperature combustion chamber," where the higher the temperature, the stronger the power, but the requirements for materials and cooling technology are extremely high. Being able to solve this shows that our industrial foundation has become much stronger.

Finally, look at the overall picture: China's path is unique, and it's even planning to build an "intercontinental fighter".

A variable cycle engine is not a new concept, and the US has been working on it for a long time, such as the F-120 engine used in the YF-23, with the core idea of changing the bypass ratio. At low speeds, more air flows through the outer bypass to save fuel, while at high speeds, the bypass ratio is reduced to increase thrust. However, we have taken a different path: the bypass ratio remains unchanged, so it is not a variable cycle engine, but a variable mode one. Don't directly interpret it as "abnormal"; we are making changes in the combustion chamber.

How is this achieved? Simply put, it has a "double insurance": an inter-stage combustion chamber that reduces the main turbine temperature to protect components, using the gas from the low-pressure combustion chamber for secondary heating to increase energy; and an outer bypass combustion chamber that further improves fuel efficiency. This design is more complex, but it can simultaneously ensure fuel efficiency at low speeds and thrust at high speeds, giving us an advantage over the American approach.

If you talk about strategic significance, it's even more profound. If the new fighter jets like the J-36 are equipped with it, and paired with a new inlet, theoretically, they can fly over 10,000 kilometers with internal fuel, becoming the world's first "intercontinental fighter." Moreover, a thrust of over 200 kilonewtons is likely to exceed the US FNX-5011 engine, excelling in both low-speed fuel efficiency and high-speed thrust.

Of course, let's be honest. From the technical principles to actual installation, there are still tough battles ahead. The Institute of Engineering Thermophysics of the Chinese Academy of Sciences and various engine groups need to coordinate well to solve the challenges of engineering transformation. But regardless, this generation-level breakthrough has already rewritten half of the rules for the next generation of air combat. In the future, the competition will be about who's engine can be "faster and more efficient."

In summary, one sentence: although this engine is still some way from engineering application, it has shown us the innovation of the Chinese people in the field of fighter jet "hearts". I think "variable mode" is not only real innovation, but also true "abnormality", not only solving the "range anxiety" of aircraft, but also putting a heavy weight on the high-speed supersonic track.

Due to the high cost of the US variable cycle engine project, it's basically unaffordable. On this track, China, as a latecomer, has a complete opportunity to take the lead. The crown jewel of the "industrial crown", the aerospace engine, we are getting tighter and tighter.

Original article: https://www.toutiao.com/article/7569051383992549903/

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