J-20 5th Gen Fighter Thread IV (Closed to posting)

[PanAsian]

Does anyone know why instead of the old all-glass bubble canopy that an arch is present in the canopy on the 2011? Is it an indication of insufficient strength in the all-glass version? Any other possible reason? And does this affect the stealthiness of the plane?

Being very late to the party I skimmed through the many posts since the latest batch of pictures started coming out but didn't see any discussion of this.

 

[chuck731]

Does anyone know why instead of the old all-glass bubble canopy that an arch is present in the canopy on the 2011? Is it an indication of insufficient strength in the all-glass version? Any other possible reason? And does this affect the stealthiness of the plane?

Being very late to the party I skimmed through the many posts since the latest batch of pictures started coming out but didn't see any discussion of this.

Adding a internal reinforcing arch allows the cockpit transparency to be thinner, and therefore lighter, as well as safer for the ejection seat to break through in case the pilot must eject.

It appears in the 2001, the canopy tarnsparency is completely clear. This means the canopy is likely intended to be jetisoned first in one piece to clear the path for the pilot to eject. In the 2011, the canopy transparency clearly contains embedded explosive cords. This means the canopy is intended to remain in place during ejection. But the transparency is to be shattered by embedded explosive cords, and the ejection seat with the pilot strapped in is then fired through the broken transparency.

 

[latenlazy]

But the picture with 1 silver exhaust and 1 standard exhaust is what makes me think that the silver exhaust is not AL-31. If both engines were AL-31, why would they change the exhaust color and petals in 1 but leave the other standard? This picture, to me, shows engine testing with 1 AL-31 and 1 engine that is not as mature as the AL-31.

Probably because they switched out the engine with the silver petal nozzles for maintenance or as a complete replacement, and switched in another AL-31 without those petal nozzles to continue testing. I suspect the silver is a plating that is meant to test IR suppressant properties, and they've probably collected enough data on it or weren't testing those properties at the time anyways so it wasn't a big deal. The black portion of the silver nozzle is probably coated with RAM. They may have even specifically switched out the AL-31's old plates there with sawtoothed ones to reduce some rear end RCS.

The logic that they switched out one engine to give the J-20 a reliable engine to test the other is not consistent with the fact that the J-20 first flew with two of those silver engines. If the engine's reliability was in question and they still needed testing, they would not have used both for first flight.

 

[manqiangrexue]

Probably because they switched out the engine with the silver petal nozzles for maintenance or as a complete replacement, and switched in another AL-31 without those petal nozzles to continue testing. I suspect the silver is a plating that is meant to test IR suppressant properties, and they've probably collected enough data on it or weren't testing those properties at the time anyways so it wasn't a big deal. The black portion of the silver nozzle is probably coated with RAM. They may have even specifically switched out the AL-31's old plates there with sawtoothed ones to reduce some rear end RCS.

The logic that they switched out one engine to give the J-20 a reliable engine to test the other is not consistent with the fact that the J-20 first flew with two of those silver engines. If the engine's reliability was in question and they still needed testing, they would not have used both for first flight.

Thanks, man. The silver coat to suppress IR has been the most plausible thing I've heard as an explanation! 3 questions:

1. Why would there be 2 small black rings of ram? That doesn't make sense to me.

2. Assuming that WS-10A produces 132kN, and is reliable enough to be in service with the J-11B, I don't see an AL-31 variant that is both in service and provides significantly more thrust to merit using that instead of WS-10A. AL-31FM2 with 145kN would be a good candidate but it's still in testing in Russia so I really don't believe that that's what's in the Chinese machine.

3. What saw-toothed petals? I haven't seen any of those on J-20.

 

[latenlazy]

Thanks, man. The silver coat to suppress IR has been the most plausible thing I've heard as an explanation! 3 questions:

1. Why would there be 2 small black rings of ram? That doesn't make sense to me.

2. Assuming that WS-10A produces 132kN, and is reliable enough to be in service with the J-11B, I don't see an AL-31 variant that is both in service and provides significantly more thrust to merit using that instead of WS-10A. AL-31FM2 with 145kN would be a good candidate but it's still in testing in Russia so I really don't believe that that's what's in the Chinese machine.

3. What saw-toothed petals? I haven't seen any of those on J-20.

Oh you're referring to the black bars on the nozzle? If I'm right about the IR suppressors that might just be part of the design.

The FM1 produces comparable thrust to the WS-10A, but one has to keep in mind it's not just about how much thrust an engine can deliver. It's also about availability and supply. My impression is that if the reliability issues of the Taihang have been sorted out, Shenyang is still probably having trouble meeting demand. It's not just the new J-11B and J-16s, but also spare engines, and maybe even engines for the J-15s.

This goes back to point one. You were referring to the black bars on the nozzles and I misunderstood and thought you were reerring to the black section behind the silver nozzle.

 

[manqiangrexue]

Oh you're referring to the black bars on the nozzle? If I'm right about the IR suppressors that might just be part of the design.

The FM1 produces comparable thrust to the WS-10A, but one has to keep in mind it's not just about how much thrust an engine can deliver. It's also about availability and supply. My impression is that if the reliability issues of the Taihang have been sorted out, Shenyang is still probably having trouble meeting demand. It's not just the new J-11B and J-16s, but also spare engines, and maybe even engines for the J-15s.

This goes back to point one. You were referring to the black bars on the nozzles and I misunderstood and thought you were referring to the black section behind the silver nozzle.

I understand that probably, WS-10A has way more demand than supply now, but I always assumed that the J-20 project was of highest priority and if it only needed a few, then Shenyang would provide them. Also, isn't the FM1 only for the Russian air force? Or you think they special-ordered a batch of them?

By the way, you're doing a great job of answering the questions I came here with this morning and I'm learning a lot. Thanks

 

[latenlazy]

I understand that probably, WS-10A has way more demand than supply now, but I always assumed that the J-20 project was of highest priority and if it only needed 2 (or 4 with spares), then Shenyang would provide them. Also, isn't the FM1 only for the Russian air force? Or you think they special-ordered 2-4 of them?

By the way, you're doing a great job of answering the questions I came here with this morning and I'm learning a lot. Thanks

They probably special ordered (I think Deino said he had some reporting on this a while ago), which shouldn't be surprising. CAC has a very strong relationship with Salyut. Besides, if I recall correctly the J-10B will be using the FM1 as well.

There's a number of other possibilities, all of which are unknowable from speculation. Maybe Shenyang just didn't have excess capacity. Maybe CAC didn't want to take the chance that if they needed more engines or assistance they'd have to wait on Shenyang. Maybe the management at AVIC didn't want CAC disrupting Shenyang's production flow. Maybe CAC is more confident with the maintenance and operations of the AL-31 than the WS-10 and didn't want the uncertainty of that to disrupt testing.

I think at the end of the day, it's just not that important which engine the J-20 is using as an interim for the WS-15. They're all interim solutions with generally the same performance.

 

[chuck731]

Is the alledgedly coated nozzle really silver? It looks white to me. I think the difference is important. White suggest the nozzle might be ceramic instead of metal.

Some of the known ceremic nozzles on latest engines are white, although in most cases they are white on the inside, not outside of the nozzle.

Some examples includes F-135 engine and the original prototype AL-41 engine that flew with Mig 1.44 prototype.

 

[latenlazy]

Is the alledgedly coated nozzle really silver? It looks white to me. I think the difference is important. White suggest the nozzle might be ceramic instead of metal.

Some of the known ceremic nozzles on latest engines are white, although in most cases they are white on the inside, not outside of the nozzle.

Some examples includes F-135 engine and the original prototype AL-41 engine that flew with Mig 1.44 prototype.

The nozzles have a luster to them in the older pics where they're still new (they seem to collect a lot of dirt and soot in their use), but I suppose that doesn't necessarily tell us much. I DO remember that someone posted China's research into silver based IR suppressors once on CDF, AND there was also that silver coating used on the stealth black hawk's tail rotor, so I think there's some plausibility to the idea.

 

[shen]

is there any close up picture of J-20's intake? does its DSI bump have the same tiny holes like those on JF17?