Chinese stealth: What can we learn from the J-20’s Zhuhai debut?

Image source: Daily Telegraph online
Looking every inch a 21st Century reboot of the fictional ‘Firefox’, the J-20’s first airshow appearance thrilled visitors. Huge, impressive and sinister- the J-20 may become the first non-American stealth fighter to enter service. We asked Justin Bronk from the RUSI think-tank what we can glean from this dramatic public appearance.
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What can we conclude about the J-20’s performance from the display in terms of energy-management/agility/manoeuvrability?
The short, roughly one minute performance is fairly difficult to judge in detail given the paucity of decent footage (only one or two decent versions that I’ve seen so far). However, there are a few indicators that I was able to pull out for whatever they are worth. For a start, the short-onset high-alpha capabilities appear to be pretty good for such a large aircraft – a function of the canard layout and clean lines, along with side-mounted intakes. Equally, the instantaneous turn rate is not too sluggish on the first break considering that it was almost certainly pulling less than the full production version will be capable of.
On the other hand, the display manoeuvres appear to have been carefully managed to avoid bleeding too much energy and one gets the impression that even with afterburners, the acceleration is less than impressive. This should not come as too much of a surprise, since jet engine technology continues to be a limiting factor for both Chinese and Russian fifth generation fighter programmes, and as previously mentioned, the J-20 is hardly a lightweight machine.
Unlike legacy Russian examples, the engines appear to be smokeless- what does this mean?
The smokeless engine indicates that the still-in-development WS-15 turbofans are running at reasonably respectable operating temperatures and with good combustion efficiency – in other words the WS-15, assuming that is what is fitted, is at least in a similar category to the latest Russian offerings (Editorial note: it is generally believed the J-20s are currently powered by improved ‘Sino-Russian’ AL-31FM2s). However, given the size of the J-20 it remains to be seen if engines can be developed which are capable of providing a good thrust to weight ratio without unacceptably reducing reliability and/or increasing fuel consumption.
What can we infer about the aircraft’s top speed from looking at it?
The J-20 has sleek lines and appears to be a good blend of aerodynamic lessons learnt in various Western and Chinese development programmes over the past thirty years. As such, it is likely to have a high top speed in the Mach 2 category, but the large size and weight of the aircraft, coupled with the developmental nature of the WS-15 suggests that its acceleration and, therefore, time required to regain lost energy during manoeuvres may lag significantly behind its Western rivals. Claims that the J-20 is capable of supercruising are probably credible, but it probably takes significantly longer to do so than the F-22.
Further thoughts?
Judging the J-20 against the F-22 and F-35 is certainly tempting, but I would suggest that the J-20 is better understood as a stealthy analogy to the F-111 than a stealth Su-35. It will be a long ranged, difficult to detect (but not all-aspect VLO) strike and interdiction fighter that can pose a serious threat to the forward bases, AWACS aircraft and aerial refuelling tankers on which the US and its allies depend in the Asia Pacific. Whilst it cannot match the F-22 or probably even F-35 one-on-one, in sufficient numbers and hidden amongst the clutter of PLAAF’s other conventional forces, it is unlikely to need to be in order to be highly effective.
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Of what could be learned from the display, one retired RAF commander joked to Hush-Kit- “Hard to say – but I know that I could strafe my name across that huge planform!”
Justin Bronk is a Research Fellow specialising in combat airpower and technology in the Military Sciences team at RUSI. He is also Editor of the RUSI Defence Systems online journal
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“In sufficient numbers”… therein lies the true question. Like the SU 57, how many of these things will be built? I don’t think that 10 or even 50 will make much of a difference in an all out shooting war.
This specific version of the J-20 is not currently being mass produced as its seen more of a stepping stone to better craft.