I think that the prototypes are yet to be tested for flying capabilities giving certain weight and other flying variables. I doubt there is a radar present. They can later remove the pitot tube if the alternative speed "meter" is reliable enough...
J-20 5th Gen Fighter Thread IV (Closed to posting)
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I think that the prototypes are yet to be tested for flying capabilities giving certain weight and other flying variables. I doubt there is a radar present. They can later remove the pitot tube if the alternative speed "meter" is reliable enough...
plawolf
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A little late to the party, but I think the hexagon meshes on the side of the intakes covers an intake and an exhaust which are used for boundary layer control inside the intake.
There would be sliding doors, which may or may not also be covered by a similar mesh screen, on the inside wall of the intake.
By opening and closing one or both of those doors, partially or fully, the J20's intake would be able to create pressure fields that push the boundary lay airflow forwards or backwards when it first hit the outside wall of the intake, which would then feed through to affect where and when the shockwaves form inside the intake, which in turn determines at what speed the airflow hits the compressor blades.
Its a pretty ingenious design, which should allow the J20's fixed DSI to achieve similar supersonic performance as traditional variable geometry intakes while retaining all the RCS advantages of the DSI. Its not a perfect solution, because the movable doors and mechanisms needed for them would surrender much of the weight and maintenance savings a basic first gen DSI would have over a variable geometry intake, but I think the supersonic performance gains are viewed as well worth the cost compared to a basic DSI.
There would be sliding doors, which may or may not also be covered by a similar mesh screen, on the inside wall of the intake.
By opening and closing one or both of those doors, partially or fully, the J20's intake would be able to create pressure fields that push the boundary lay airflow forwards or backwards when it first hit the outside wall of the intake, which would then feed through to affect where and when the shockwaves form inside the intake, which in turn determines at what speed the airflow hits the compressor blades.
Its a pretty ingenious design, which should allow the J20's fixed DSI to achieve similar supersonic performance as traditional variable geometry intakes while retaining all the RCS advantages of the DSI. Its not a perfect solution, because the movable doors and mechanisms needed for them would surrender much of the weight and maintenance savings a basic first gen DSI would have over a variable geometry intake, but I think the supersonic performance gains are viewed as well worth the cost compared to a basic DSI.
If that's what it is it makes me wonder if they considered other methods like the one the F-22 employed. This particular one might also have lower weight penalties than it sounds, if they can build the doors and it's mechanisms into the wall of the inlet.
Using f-22 as analogy, fixed intake needs the ability to bleed off substantial amount of excess air in order to operate efficiently at all speed ranges. Again using f-22 as analogy, the bleed air vents needs to be much larger than the hexagons on the j-20. On the f-22 they are found in the form the big Venetian blind style doors with zig zag edges on the upper surface of the f-22 behind the intake. So I think these meshs on the j-20 are for some other purpose.
They could simply be radar shielded vents for the avionics cooling systems.
Cooling vents may be the most simple answer, but from plawolf's explanation this sounds more like boundary layer management system than a bleed system.
I am not sure if his combined boundary layer control and pressure management system is anything more the speculation. F-22 manage pressure by using big doors in the upper surface of the aircraft to divert air straight out of the intake ducts. I assume j-20 has these too, we just haven't seen them open yet.
This is possibly because we haven't had many good photos of the upper surface of the plane taken while the plane is in different flight regimes.
Of course it's speculation, but it doesn't sound like a terrible guess, certainly no better than any other until evidence comes up.
I don't think the J-20 has those vents that the F-22 has. I've checked images of the F-22 and YF-22 and those vents are pretty obvious. We do have a few decent pictures of the J-20's top, and there are vents or exhausts, but they seem rather small to be bleeds for the inlet tunnel.
On the f-22 the doors are an overlapping Venetian blind design. If they were flush mounted doors they would not be obvious, nor would they look different from a service panel.
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But they can still be seen from a dorsal view on the F-22, and there are pics of the J-20s top where panel lines are visible but there's no sign of such a structure. Anyways we should have a much better view of the panel lines with 2011, so we''ll have a better idea once those pics turn up.
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