Waiting for a miracle that most likely won't happen
"Will it fly or not?" - this question is asked in two countries on both sides of the Pacific Ocean. That is, in the USA and in China. Moreover, they are asking about the same aircraft, meaning not so much the fact of whether it will fly or not, but how it will fly. This point is much more important.
We already reviewed the J-20 when it first appeared, and, it must be said, there was little that was positive.
The Chengdu J-20 is a large (length 23 m) and heavy (takeoff weight up to 40 tons) canard fighter, created far from the most advanced technologies. You could say that "I cobbled it together from what was there." And it was largely from the MiG-1.44/MFI 1.44 prototype, data on which somehow ended up in China.
IFI 1.44
J-20
The fact that the J-20 is in many ways outrageously similar to the MFI 1.44 has been said more than enough. The Chinese aircraft also has a delta wing with extensions and an all-moving canard. The vertical tail is two all-moving vertical stabilizers, widely spaced in terms of inclination to the sides. The layout is the same as the MFI 1.44, and the dimensions are almost the same. But here's what "almost" is.
Our aircraft had a larger wing, which obviously provided better maneuverability. Plus 1.44 was much lighter than the Chinese aircraft, and even the lack of weapons could not be discounted: the difference in maximum weight reached almost 20 tons.
There were some differences: the Chinese made the tail fins collapse, their own configuration of the canard wings and wing extensions. And they ripped off a little from the Americans: the nose section (many noted) was copied from the F-22A, the air intakes and canopy design are from the F-35.
Overall, it turned out to be an ugly aircraft, cobbled together not only from solutions by designers from different countries, but also taken from aircraft of different generations. And the Chinese will clearly have to not only regret many of these borrowings, but rather work hard to correct and modernize them.
Especially if we are talking about the popular stealth. No, the J-20's shape is very similar to something stealthy, but its content... Let's be honest: the aerodynamic design with a canard for a stealth aircraft is not the best solution. The canard and ventral ridges increase the aircraft's radar signature, and there is no easy way to fix this.
The air intakes, "copied" from the F-35, will also cause a desire to redesign them over time. While the J-20 flew on the frankly weak WS-10A, this did not affect it at all, but it was detrimental from the start, because the F-35 was not planned for high speeds, especially at many Machs at supersonic speeds. Yes, the shape of the air intakes will allow for the installation of larger, and therefore more powerful, engines, but this does not mean that the aircraft will immediately fly faster.
Although... it's hard to say what could be worse than the WS-10A with its disgusting dynamics and low stability in different operating modes. Plus, this engine has almost no service life. Because no matter what you put in place of the WS-10A, everything will be fine.
In general, in China, pilots were waiting for the WS-15 like manna from heaven, work on which began in the 90s of the last century, and the refinement was going on from the moment of the first launch in 2006. Let's draw conclusions, because perhaps we have waited for it.
Of course, it is impossible to get a clear picture of the J-20A equipped with Chinese-made WS-15 engines. There, in the Celestial Empire, they know how to keep secrets very well. Although the appearance of a photo of the J-20A with engines different from the original ones in American military magazines suggests that not everything is as wonderful as Comrade Dong Jun would like. Or, on the contrary, everything is going according to plan, it is difficult to say now. But now it is becoming clear that the most significant drawback of the J-20 - its power plant - is on the way to being eliminated. Unless, of course, this is an attempt to deceive and confuse everyone.
The photo in question began to spread widely on social networks last weekend. It shows a prototype J-20A with serial number 2052 on a runway in an unknown location. It is quite possible that this is the main test airfield of the manufacturer Chengdu in the city of Chengdu. Evil tongues in the United States claim that there are two aircraft with the number 2052, one flying, with old engines, the second - with non-existent ones. But in the photo, the fighter is visible from behind, which allows you to examine in detail the nozzles of the turbofan engines, which do not look like WS-10A or even WS-10G. Is this really a WS-15? It is quite possible. The fact that the aircraft is covered with a characteristic yellow primer, which is applied before the final paint, adds credibility. That is, as is, one of the prototypes.
The J-20A is an advanced single-seat version of the baseline J-20, with changes that include a revised fuselage shape, including a reprofiled nose cone, a deeper bulge, and a slightly raised cockpit, as well as WS-15 engines. The extra space in the tail is likely intended to accommodate avionics and/or fuel. Meanwhile, the new engines will definitely require modified intakes with a slightly smaller bulge (DSI intake design) on the leading edge to optimize airflow, at least according to the American specialists who designed the original intake.
The thrust-to-weight ratio of the J-20 is low, and it clearly lags behind the Su-57, the F-22A, the Su-35S, and even the Su-30. The chances that Russia will sell more powerful engines for the J-20 are slim. Unless, perhaps, within a solid batch of Su-35s. Here, of course, there are options - Russia can supply more engines than aircraft if the deal is concluded. And turn a blind eye to the fact that some of them are not being used for their intended purpose.
But this will not solve the Chinese problems, because more than 20 J-300s with “first period” engines have already been produced.
And this, by the way, is 600 engines. With a limited resource, and in general the resource of any engine is limited to a certain number of working hours. And such a huge number of engines will have to be replaced as their resource ends. Accordingly, supplies from Russia will not solve this problem. So until there is a reliable and powerful Chinese engine, any developments on the new generation will be nothing more than child's play.
So the actual appearance of the WS-15 is a real step forward for the Chinese aviation. If this really happened, because it has been noted that this is often the case: Chinese aviation photos are published several months or even a year after they were taken. What is, is.
Regardless of when the photo was taken, it certainly gives a good view of the J-20A's WS-15 turbofan engines, engines that are expected to significantly close the gap between Chinese fighters and their newest Western counterparts.
As early as March 2022, reports said that a J-20 with a WS-15 engine had flown, although it was known that only one of these engines was installed, which is common for early tests. The second was a Russian AL-31, which is generally understandable, and in the event of something happening, it was our engine that was hoped to save the prototype.
In December 2022, images of serial number 2051 emerged online, an example of a J-20A variant that was expected to receive the WS-15. However, J-20A serial number 2052 was reported to have flown with WS-15 engines installed in June 2023, when photos and videos of the test flight began circulating on social media.
The first photographs of the J-20A with the WS-15 engine were of poor quality, with the exhaust stacks darkened, making it difficult to definitively determine whether the aircraft actually had new engines installed or whether it retained the previously installed WS-10 series turbofans.
Or, in general, it is worth remembering that the J-20 prototypes and the first production models were equipped with Russian-made AL-31 turbofan engines. That is, one model was equipped with a whole bunch of engines: WS-10A, WS-10B, WS-10C, WS-10G, AL-31 and, finally, WS-15. And it is not always possible to distinguish one from the other.
As for the WS-15, there are few reliable facts about it. So far, no photos or videos demonstrating the engine, or even a full-scale model, have appeared publicly. The media operate exclusively with figures, also of unclear origin (links lead to the School of Mechanical Engineering of Shandong University), which indicate that the WS-15 thrust should be from 150 kN, which is generally less than that of Russian and American engines, but more than that of Chinese ones (there, depending on the modification, from 120 to 140 kN).
By the way, it is absolutely impossible to see the mechanization controlling the thrust vector change in the WS-15 in the photo, despite the fact that the WS-10G variant already had a thrust vector control. And the pictures show an engine with a standard nozzle.
This does not mean that the WS-15 does not have a UVT, the initial tests (although - since 2006, so to speak) can be carried out without a UVT, installing all the control mechanics later is not a big problem, the only question is exactly what was not installed right away.
And it turns out that the only advantage of the WS-15 over the WS-10 is its greater thrust. Yes, 2 kgf is quite decent, it is at the level of the F-000, whose Pratt & Whitney F22-PW-119 produces approximately the same 100 kgf, but has a vertical thrust booster and a non-afterburning mode of 15 kgf for the so-called "supercruise". So the Chinese comrades have something to think about: the F-000, with all its disadvantages, can fly for quite a long time with a full combat load at supersonic speeds without using afterburners. Whether the J-10 will be able to fly like that is a big question for a large aircraft.
Thrust at the level of the Raptor and Su-57 is quite good, but in terms of efficiency/range, stealth and maneuverability - here there are more questions than answers.
Kind of a side note, but thrust is not what makes an engine good for supersonic cruising. It's all in the package. But what sets the F119 apart from other engines for the better is that it has very high exhaust velocity/energy without afterburner, meaning it gets the aircraft up to high speed and beyond with relatively low fuel consumption, and even into supersonic flight. This in turn allows it to have a small engine and intake area and achieve high supersonic speeds with normal thrust.
To achieve this, the engine must have very low bypass (since the bypass air moves very slowly), and this requires very high turbine inlet pressures and temperatures while achieving decent efficiency. The F119 has one of the lowest bypass ratios of any modern fighter engine, at 0,3:1.
And here the main question is not whether China has created an engine with a thrust of more than 15 kgf. This is not the most difficult thing, the question is whether they did it on a reliable and sufficiently efficient engine with a sufficiently "hot" exhaust for high-speed (M000+) cruising flight. And here there are many doubts.
If you look at the American assessments, and at the beginning of each year the Pentagon publishes a report, including on the military power of China, as its main potential adversary, then this year there were expectations that due to the WS-15 engines the J-20 will be able to obtain that very coveted ability for supersonic cruising flight and increase the capabilities in terms of combat load of the internal compartments.
But overall, the generals are calm. “It’s not something to lose a lot of sleep over,” U.S. Air Force Gen. Kenneth Wilsbach, head of Pacific Air Forces, told reporters in September 2022. “We’re certainly watching them closely and seeing how they evolve.”
But we know that a certain degree of self-confidence is characteristic of the American military. However, cases of deep disappointment, starting from the same 2022, have occurred among the US military,
At the same time, the J-20 engine upgrade is not the only program underway to expand the aircraft's capabilities. The two-seat J-20B is currently undergoing testing, and information has leaked regarding this aircraft that one of its functions will be to control drones. It all looks quite logical, adding a second crew member would make the J-20 more suitable for this task. There is no doubt that China will be able to develop and build wingman drones, and upgrading the aircraft to control a flock of wingmen would place the J-20B in a unique niche among existing fifth-generation fighters, because the only one that has demonstrated anything in this direction so far is the Russian Su-57. And the American NGAD platform so far looks more like a goose with broken wings.
The development of the WS-15 is critically important for China. Significant achievements in the country's aircraft engine industry are the key to the development of aviation in particular and the country's defense capability in general. The development of modern, highly efficient jet engines has long been the Achilles heel of China's aerospace industry. The aircraft industry has long relied on Russian-supplied engines, but if the Chinese industry can put its own engines on stream, this will have an extremely positive effect on China's aviation industry.
And if Chinese engines of their own design can become equal to Russian and American ones in terms of reliability and durability... Then the gates of the world aircraft market will open wide for China, where China has so far sometimes pushed its aircraft in the category "for the poorest".
But for this to happen, a miracle must really happen. And as practice shows, it is not obliged to do so. The fact that the WS-15 seems to have taken its rightful place does not mean that everything is as rosy as we would like. Twenty years of war for the engine among Chinese aircraft engineers indicate that the path is still far from its end.
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