Ask the expert: What does the J-20’s configuration reveal?
Jim Smith had significant technical roles in the development of the UK’s leading military aviation programmes from ASRAAM and Nimrod, to the JSF and Eurofighter Typhoon. We asked his opinion on what we can learn from looking at China’s next superfighter, the Chengdu J-20.
“The J-20 and the Su-57 are generally described as F-22 Raptor-class aircraft. In many ways this is true, but I think the J-20 is particularly interesting because of its rather different configuration.
The J-20 has a canard-delta rather than the (essentially) tailed-delta of both the Raptor and the Su-57. Additionally, unlike Typhoon, the canard is not closely coupled to the wing.
What might be the trade-offs here? I think the main benefit to be gained from this arrangement is the carriage of significantly more fuel, coupled with the scope for use of a longer weapons bay. The overall outcome could be a remarkable multi-role aircraft, with a particular strike role, carrying area-denial weapons. These might include, but are unlikely to be limited to, anti-ship missiles. The additional fuel could confer either additional range, or long combat persistence, and this suggests that, if armed with a long-range AAM a role as an anti-AWACS or anti-tanker system.
The large weapons bay might also provide sufficient volume for a wide range of strike weapons, but I would suggest this as a secondary role compared to the conflict-shaping area-denial role. Future internal carriage of high-speed weapons is a speculative possibility.
What of the compromises? I would suggest less energy manoeuvrability, as the configuration is likely to have somewhat higher transonic drag. In addition, signature (other than head on) looks likely to be a bit greater. Head on signature could be comparable to competing systems if appropriate engine installation and airframe treatments are used. The canard, I am assuming, will be held at low deflection for supersonic flight, especially if Su-35-like thrust vectoring is available to trim the aircraft. It is not clear from open source literature if this is the case, but if I were a PLA customer, I would be looking for it.”
Some have speculated that the J-20 design may have been based on the Russian MiG project 1.44 tactical fighter design of the 1990s. MiG had been working on new generation fighters since the 1980s, and MiG’s 1.44 technology testbed flew in support of this effort, taking its first flight in 2000.
The theory goes that China bought research data and possibly worked with MiG to create the J-20. Though it is true that several Chinese aircraft (notably the Kamov designed CAIC Z-10 attack helicopter) were Russian designs never ordered by their parent state, the idea that MiG helped with the J-20 does raise some big questions. The first is ‘where did the money go?’ If MiG did provide vital work for a massively important programme they must have negotiated a very poor deal. MiG has been in a perilous state for years, in the 1990s in the chaotic early days of the Russian Federation, it fell out of favour. Despite its impressive history, it was at the mercy of officials friendly to the rival Sukhoi design bureau. The company limped on in the 1990s and early 2000s, and certainly didn’t seem buoyed by mysterious funds. The MiG 1.44 was killed for good in 2000, so presumably the Chinese relationship would have happened around this time. It could have happened before, as anything was possible in Russia in the 1990s, but selling high-tech secrets while trying to pitch the same projects to your own government seems a risky strategy. We also have the question of when this collaboration could have happened. According to Western sources, development of the J-20 began in the late 1990s, and it was officially announced by the Chinese in 2002. Things were still pretty terrible for MiG at this time, later still MiG were caught trying to palm off old (or ‘inferior quality’) MiG-29s as new aircraft to the Algerian air force. The infuriated Algerians returned the initial fifteen aircraft. This move severely damaged MiG’s reputation – would a company with lucrative secret deals have bothered with such dangerous chutzpah?
There’s also the question of what the design similarities are. Though superficially similar the two designs have a great deal of differences. They do indeed have a similar tailplane configuration, and are both canard deltas — however we then start running out of physical similarities. Now at this point it should be noted that the the Russian aircraft was a testbed and the eventual aircraft may have been different in key details, though MiG has never confirmed this was the case. So lets look at the differences:
The J-20 uses the Lockheed Martin model for reduced radar conspicuity. The Raptor-like forward fuselage, angle alignment and F-35-style inlets are a far cry from the squashed forward fuselage and underslung box intake arrangement of the MiG. The canard foreplanes also seem to have a different relationship to the wing. The MiG’s foreplanes are far closer to the main leading edge of the wing, the J-20s meet a leading-edge root extension. The MiG’s foreplanes are mounted higher than the wing, the J-20’s start at the same height as the wing and at a pronounced dihedral angle. Not everything can be judged from the outline of an aircraft, and is possible that much in the way of internal structure or materials was directly informed by the Russian aircraft. If this was the case, then much Lockheed Martin DNA was also spliced into the programme. The LM stealth solution could have been arrived at completely independently, but this seems unlikely: a look at the other entrants to the ATF contest reveal there is more than one way to skin a cat. If American allegations of Chinese espionage relating to the F-35 are grounded, the similarities to the US’ fifth generation fighters may be more than skin-deep.
In conclusion, the evidence is far from damning, and appears to lead back to the Skunk Works as much as it does to Moscow.
Here is RUSI think-tanker Justin Bronk ‘s assessment of the J-20.
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