J-20 5th Gen Fighter Thread VI

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kurutoga

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once you breach the Mach barrier, you light up the IRST or the EODAS pretty well.

Why is that? IRST/EODAS are both based on cameras of infrared and visible lights, both are going to have limited range and the environment will cause high noise levels. If the jet go supersonic without using burners and is still very far away, why do you think the jet reflects/emits more infraed/visible lights?
 

jobjed

Captain
Why is that? IRST/EODAS are both based on cameras of infrared and visible lights, both are going to have limited range and the environment will cause high noise levels. If the jet go supersonic without using burners and is still very far away, why do you think the jet reflects/emits more infraed/visible lights?

I think aerodynamic heating during supersonic regime would contribute somewhat. A ~50°C aircraft would be like 100K hotter than the upper-atmosphere air which is many score degrees below freezing.
 

latenlazy

Brigadier
Is that the real reason the Chinese picked up the Su-35s? So they could use it to establish a higher-accuracy simulator craft?

That said, for all the talk of the J-20's supersonic maneuverability, once you breach the Mach barrier, you light up the IRST or the EODAS pretty well. The one question is whether the J-20 can successfully use supercruise when subsonic F-35s are sitting and watching.
At a competent supercruise speed a plane is probably going fast enough to clear the detection radius of infrared sensors in 4-5 minutes. They effective radius of the SRAAM you're firing is probably even shorter than that (of course if they're approaching you they'll be closing the range earlier, but by the time you fire their MAWS should be going off, and it's not like fighters usually rush head first into one another). Trying to hit target with a full head of steam doesn't bode well for the pK of the missile. What you see in an approach vector is also not the hottest part of the plane, and if you can see their exhaust they're probably flying away from you. Even if you can see a supercruising fighter coming at you because of greater airframe heating, it becomes pretty pointless if you can't hit them before they get close enough to see you and exploit their kinematic advantage.
 
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kurutoga

Junior Member
Registered Member
I think aerodynamic heating during supersonic regime would contribute somewhat. A ~50°C aircraft would be like 100K hotter than the upper-atmosphere air which is many score degrees below freezing.

I thought infared (high frequency) will decay fast, that is why they are not for long distance. That is the reason why we don't have x-ray radar.
 

SpicySichuan

Senior Member
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There's just a similar discussion at the PDF and again the usual suspects are again hyping it as proof for their theory, the J-20 uses a TVC-engine from day one ...

Anyway he posted this sentence:



Ok, he said (3:48) that the J-20's internal weapons bay carries more weapons than that of F-22. How's so? Can anybody explain? From what I know, J-20 can only carry two SRAAMs and BVRAAMs, but F-22 can carry two SRAAMs and six BVRAAMs.
 

Richard Santos

Captain
Registered Member
The inside edge of the booms
Is that the real reason the Chinese picked up the Su-35s? So they could use it to establish a higher-accuracy simulator craft?

That said, for all the talk of the J-20's supersonic maneuverability, once you breach the Mach barrier, you light up the IRST or the EODAS pretty well. The one question is whether the J-20 can successfully use supercruise when subsonic F-35s are sitting and watching.


Supercruise confer several advantages that are not nullified by reduced stealth:

1. it confers greater initial energy to the weapon the aircraft fires, so effectively increase the range and terminal menuvering envelop of the missile it fires.

2. It allows supercruising firghters from a larger operational area to congregate into the battle area on short notice to achieve local parity or superiority in number

3. It makes the supercrusie a considerable more difficult target from energy perspective for enemy missiles, and greatly reduce the area in which the enemy can effectively engage the super rising fighter, and also reduce the no-escape zone available to energy SAM and AAM.

furthermore, The maneuverability of a fighter at any given attitude is largely governed by the difference between the fighter’s maximum speed at that altitude, and its stalling speed. As altitude increases, an aircraft’s stall speed increases. At high altitudes, an normal fighter without supercrusing capability may not be able to maneuver at all without lighting its afterburners because its maximum speed with military thrust is essentially the same as its stall speed. If it tries to maneuver, it would lose speed and stall. A fighter with supercruise capability, on the other hand, remain maneuverable because it still has a large margin between its top speed and stall speed.

So even if using popular figures like turn rate and claims speed, it may appear a normal fighter approaches a supercrusimg fighter in maneuverability. In reality, the very virtual of being able to supercruise gives the supercruiser a vastly larger maneuvering envelope in practice than any normal fighter.
 
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ougoah

Brigadier
Registered Member
Ok, he said (3:48) that the J-20's internal weapons bay carries more weapons than that of F-22. How's so? Can anybody explain? From what I know, J-20 can only carry two SRAAMs and BVRAAMs, but F-22 can carry two SRAAMs and six BVRAAMs.

We know J-20 can carry at least 2 sraams in side bays and 4 mraams in main bays. They main bays of J-20 may be deeper than F-22's but I doubt they are wider or longer. Feels like he may be referring to ability in carrying ashm, larger guided bombs, and other types of missiles like anti-radiation, and air to surface. We know J-20 probably can't carry the long range missile spotted on J-16. I'm fairly confident that J-20 can eventually carry 6 mraams when they make them with collapsable and retractable wings. Maybe even smaller diameter ones that don't compromise range. Chinese AAMs are slightly fatter and longer than American counterparts so eventually it may be able to carry at least as much if not more than F-22.

What I found interesting was his dismissiveness of the F-22. He mentioned that is has had many problems and that's been shown in how many accidents it's been in, the oxygen problems, and the times it's been grounded for various reasons. He suggests that the reason they capped the production and stopped it was because of the design flaws with this fighter. F-35 took much longer in the design and testing phase because they've perfected the design and worked out the bugs. Fifth gen is extremely difficult and China manged to get there eventually, hinting at J-20 being a very complete product as it is now.
 

siegecrossbow

General
Staff member
Super Moderator
Feels like he may be referring to ability in carrying ashm, larger guided bombs, and other types of missiles like anti-radiation, and air to surface. We know J-20 probably can't carry the long range missile spotted on J-16.

There is always the option of carrying it externally. :p
 
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