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

[Engineer]

haha haha so tell me how avic claims J-10 has a speed of Mach 2.2 and later in Zhuhai they say Mach 1.8 uhmm....... strange do not you think?


haha the case is closed is true, since F-35 and JF-17 never claim speeds of Mach 2, only you in your fantasy, since AVIC claims J-10 has a max speed of Mach 2.2 but J-10 has a variable geometry inlet.

You cannot prove DSI has a limit of Mach 1.8, so you conjured up an obviously false statement then claim that it was I who said it. What you said is known as a

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. The following research paper made it pretty clear by saying "at Mach 2.0 the pressure recovery ratio (of a DSI) is 0.87".

So, your claim about DSI being limited at Mach 1.8 is a myth. Case closed.

 

[Engineer]

Could be that the J-10 specs shown at Zhuhai are for future export, and Mach 1.8 will be the speed of any exported J-10. They probably don't want to artificially inflate the specs of their exportable fighters and then disappoint prospective customers later.

From a technical perspective, having two top speeds in the same fighter variant is not surprising at all, especially if China uses one set of engines for export versions and another for domestic use.

Mach 2.2 could also be top speed at clean configuration, whereas Mach 1.8 being the top speed at useable configuration.

 

[Skywatcher]

haha haha so tell me how avic claims J-10 has a speed of Mach 2.2 and later in Zhuhai they say Mach 1.8 uhmm....... strange do not you think?


haha the case is closed is true, since F-35 and JF-17 never claim speeds of Mach 2, only you in your fantasy, since AVIC claims J-10 has a max speed of Mach 2.2 but J-10 has a variable geometry inlet.

So Mach 2.2 and Mach 1.8, do any of those figures deal with things like external stores and payload?

You tell me, since you brought that up.

 

[MiG-29]

Could be that the J-10 specs shown at Zhuhai are for future export, and Mach 1.8 will be the speed of any exported J-10. They probably don't want to artificially inflate the specs of their exportable fighters and then disappoint prospective customers later.

From a technical perspective, having two top speeds in the same fighter variant is not surprising at all, especially if China uses one set of engines for export versions and another for domestic use.

Su-34 has no variable geometry so it flies at Mach 1.8, if you do that to a J-10, yes is possible the export version of J-10 might be slower, but considering J-10A is not that special interms of stealth and is barely comparable to MiG-29K or Gripen it will lose a lot of its appeal.

It could be i do not deny it

 

[kyanges]

Isn't there an aerodynamic thread to discuss this stuff in? Or was that closed? Actually, I don't mind the DSI discussion, but I would like to see it at least better related to the J-20.

 

[MiG-29]

So Mach 2.2 and Mach 1.8, do any of those figures deal with things like external stores and payload?

You tell me, since you brought that up.

If the J-10 has a speed of Mach 1.8 means then it is very draggy, an armed MiG-29 easily reaches Mach 2.35, high speeds are very important, so i do not think the Chinese say Mach 2.2 as a joke, J-10A flies Mach 2.2 armed at least with a few missiles.

 

[MiG-29]

When the F-22 first came out the top speed was listed as Mach 1.6, then figures were being thrown around Mach 2.0 a few years later. Now some sources go as high as Mach 2.2 or Mach 2.0+. These numbers don't mean anything. The J-10's Mach 2.2 speed could have been pure speculation, or they could have down-rated its maximum mach number, or it could be related to the engine. You're using weak evidence to assert strong conclusions. Doesn't work like that.

AVIC is an official source, in in fact is a good as Sukhoi, so J-10A most be very fast and i think armed.

J-20 with DSI will fly Mach 1.8 with supercruise speed nothing is bad about it, is just pure specualation and senseless rumours that its DSI is variable, when in reality DSI are fixed and the protection J-20 gets is stealth that protects it from being detected, even JF-17 gets the same protection, and J-10B too.


But here the idea DSI can get beyond Mach 2 is just a fantasy, there is always compromise in any feature, DSI is cheaper and adds stealth but limits the speed.

 

[Player99]

look i am not trying to prove you are wrong, it is simply you do not understand why DSI exist, they are fixed to reduce weight and not moveable to reduce stealth price, you make it moveable you lose all advantages.

most myths about J-20`s intakes are rumours without any shred of real knowlewdge of how intakes work.

Do you have to feel and sound so patronizing, hence annoying? Let me put it clearly now: I understand what DSI means and its limitations you repeated ad nauseam. If you want to refute what I said, you should have proven, with some shreds of fact, that DSI definitely cannot be made adjustable without losing all the advantages, shouldn't you?

Why do you have to always believe that you are smarter than anyone or someone here, let alone the real experts at CAC? Is that an IQ thing or an EQ thing with this peculiar personality trait of yours?

 

[Engineer]

DSI can get you to Mach 2, true but the matter is the engine, PAKFA can get up to Mach 3 theoretically, but it won`t go more than Mach 2.5 in real life.

The engine life is what limits the speed, at speeds of Mach 2 the DSI on F-16 or J-10B will have lower pressure recovery and thus efficiency.

a Mach 1.8 is the realistic speed for a DSI equipped J-10 and a J-20.

You are spouting rubbish. First, engine life has nothing to do with speed. Second, engine does not affect pressure recovery. It is actually the reverse with pressure recovery affecting engine performance. Thirdly, you have no evidence showing what the "realistic" speed of J-10B or J-20 is. The fact is, DSI described in the paper actually has the same pressure recovery ratio as that of a 3-shock variable geometry inlet on the F-4D. The paper says "at Mach 2.0 the pressure recovery ratio is 0.87":

When we compare that number to the data points below, we see the inlet on F-4D at Mach 2.0 also has the same pressure recovery ratio.

In other words, DSI has similar performance as a 3-shock variable-geometry inlet.

 

[airsuperiority]

I doubt the J-20 will ever go mach3, but merely because I don't see PLAAF needing the J-20 for that.
And I also don't think speed is limited to merely engine output as you have said, mig. What happened to drag and altitude? Nobody care about those anymore?