Why is the J-20 using Russian AL-31 and not WS-10 engines ? Its a twin engine plane like the Flankers. Reliability is not that big of an issue as with the single engine J-10's. The AL-31 series 3 has a thrust of 137 kN and the WS-10B said to have a thrust of 135 kN so not that big of a difference.
J-20 5th Gen Fighter Thread V
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Doable but self confidence issue. They feel AL-31 is abit more safe.
There are many other attributes to a fighter engine beyond reliability and thrust. There is resistance to compressor stall, which can be critical for fighters maneuvering near edges of its performance envelope. There is the responsiveness of the engine to throttle inputs, smokiness of the engine exhaust, resistance to flameout when cutting in afterburners, etc. basically we have no idea where ws-10 falls short relative to the Russian engine.
A better question is why should the J-20 change from Al-31 series 3 to WS-10B?
Both engines are of similar thrust category, so it's not like changing to WS-10B will significantly enhance the aircraft's performance (and we also have no evidence of any difference in reliability, MTBO etc, so let's assume they're similar). OTOH changing engines will still require a period of testing and verification of J-20 with the new engine regardless which will mean additional time and money. Adding on interim J-20s with WS-10Bs will also complicate the logistics of J-20s, as they'll be split between Al31Fs and WS-10Bs. CAC also appear to have a fairly steady supply of Al-31 series 3, and more importantly this engine is still being used as interim propulsion anyway, where WS-15 is meant to become the true long term powerplant.
Putting it simply, changing from Al-31F series 3 to WS-10B provides no meaningful improvement in performance, and integration of a different engine will require time and money as well, all for an interim solution... so it actually makes sense to not change to WS-10B.
The two reasons why I can see why it would make sense to change from WS-10B to Al-31F is if the supply of Russian engines suddenly dries up for some reason and they are forced to change their interim engine type; with the second reason being if WS-15 becomes continuously delayed to a point where the Air Force sees positive long term consequences for changing to WS-10B.
vesicles
Colonel
I think there is a J-15 with WS-10 engines. Given the high requirement of a carrier fighter for its engines, I would say the PLA is pretty confident about their WS-10.
I agree with Bltizo that it's likely more about the logistics that it makes more sense for them to keep the AL-31 on the J-20 at this point.
b787
Captain
If you study the design philosophy of the J-20 fins you will be a bit surprised, and the reason you give does not hold water, there are aircraft which have very weird vertical stabilizers configurations
You can set the vertical stabilizers on the wingtips like this aircraft with canards has, see the links bellow
You can set the vertical stabilizers on the horizontal stabilizers, see link
see the UAV has canted inward vertical fins
Fighter aircraft cant their vertical stabilizers mainly for stealth requirements, so is mostly not aerodynamic reasons as you claim.
You can set the vertical stabilizers on booms like the F-15, MiG-29, Su-27 so there is no need of any canting, on the broad fuselage of F-14 there is not even need of booms
So why not set them on the wings? the reason is the torsional forces, J-20 is heavy, most supersonic aircraft are very heavy, the reason is fuel, jet aircraft carry lots of fuel, so at high G, the 30000kg weight become really heavy loads just multiply 30000 kg by 9Gs, the best place to set the stabilizers are the fuselage engine nacelles, on the SR-71 these are engines pods.
J-20 went for a strange vertical stabilizer configuration, mainly because they did the opposite J-31 did, on the J-31 they set larger rudders on larger vertical tails, avoiding vertical ventral fins, Chengdu went kind of weird for a stealth fighter by fitting ventral fins, something most stealth fighters avoid, they could simply had fit large vertical fins like J-31, since is pretty obvious the dorsal vertical fins are not enough at high AoA and it is possible stealth requirements affect its effectiveness
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B787 we have an aerodynamics thread, and I would recommend one of the mods move your several off topic posts there. You seem to like posting "flame bait" and then when "pinched" by your own lack of practical experience, love to obfuscate and throw handfuls of "dust in the air". I'm rather afraid that you might be my old buddy Mig-29, with your never ending Russian love, and rather off-handed criticism of the J-20.
You seem to suffer "information overload", while lacking practical ability to apply it to the topic at hand?? There is NOTHING strange about the J-20's verts or vents, they work, and enable the J-20 to recover from post-stall maneuvering without OVT.
WS10 supposely cost more than AL31
Have you some prices ?
No, I just remember reading it in Chinese forums. Don't remember reading any actual figures
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