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

[Player99]

When the J-20 first came out, what looked like a lip-like structure at the inlet was speculated to be adjustable.

You are right about that. But it then turned out that there was only one side that had that "lip", so people felt that it couldn't be that. And also in the beginning some "insider" had said that the adjustable part was within the intake... Anyway, we just don't know and have to wait and see.

P.S. Gee, I just turned the page again! ...Player call Brat, Player call Brat. Come in and interpret this!

 

[MiG-29]

I think you are too eager to prove me wrong to notice that I said we were told that this DSI was adjustable... We just don't know how exactly it was realized... and sure we are even not certain about this adjustable DSI rumor, but after all it is a possibility. That's why I suggested that we be patient.

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.

 

[Skywatcher]

J-20 will never make it at Mach 3, fixed inlet, DSI is a fixed inlet therefore as the shocks move out and in of the intake will simply damage the engine, this type of news really ruin all this threads where fantasy basicly mixed with lack of knowledge.

T-50 can fly at Mach 3 but its inlet is with variable geometry.

Oh, this is just hysterical! Where did you hear that little gem about the T-50 going to Mach 3?!

Or you could just modify parts of the WS-15 itself (moveable parts in the fan's cone).

 

[MiG-29]

Oh, this is just hysterical! Where did you hear that little gem about the T-50 going to Mach 3?!

Or you could just modify parts of the WS-15 itself (moveable parts in the fan's cone).

T-50 does not get up to Mach 3, it can fly up to mach 2.5, but the T-50`s intake is designed up to mach 3, that is its design mach number.

where did i hear that? answer is the Russian patent office and Sukhoi patent

Patent for PAKFA T-50 intake design it says it allows for speeds up to Mach 3

Преимущественной областью применения изобретения являются самолеты с ТРДД с максимальным числом Маха не более 3-х

and has reduced RCS

Изобретение позволяет повысить газодинамические характеристики воздухозаборника, а также снизить его радиолокационную заметность. 3 з.п

Please, Log in or Register to view URLs content!

Please, Log in or Register to view URLs content!

however the patent says the intake is variable, it is basicly the F-22`s intake with moveable parts

you can believe J-20 reaches mach 3 if you wish, but the physics of intake design limit the capture area and the intake throat size and the need for multiple shocks, anyway i won`t go further but just read about intake physics by your self and why DSI are fixed.
Tip read about SR-71`s intake design

 

[Skywatcher]

T-50 does not get up to Mach 3, it can fly up to mach 2.5, but the T-50`s intake is designed up to mach 3, that is its design mach number.

where did i hear that? answer is the Russian patent office and Sukhoi patent

Patent for PAKFA T-50 intake design it says it allows for speeds up to Mach 3

Преимущественной областью применения изобретения являются самолеты с ТРДД с максимальным числом Маха не более 3-х

and has reduced RCS

Изобретение позволяет повысить газодинамические характеристики воздухозаборника, а также снизить его радиолокационную заметность. 3 з.п

Please, Log in or Register to view URLs content!

Please, Log in or Register to view URLs content!

however the patent says the intake is variable, it is basicly the F-22`s intake with moveable parts

you can believe J-20 reaches mach 3 if you wish, but the physics of intake design limit the capture area and the intake throat size and the need for multiple shocks, anyway i won`t go further but just read about intake physics by your self and why DSI are fixed.
Tip read about SR-71`s intake design

Thanks for the idiot strawmanning. I never said that the J-20 could reach Mach 3.0.

Going by your logic, there's no reason why the J-20 couldn't have a similar intake arrangement closer to the engines.

 

[MiG-29]

Thanks for the idiot strawmanning. I never said that the J-20 could reach Mach 3.0.

Going by your logic, there's no reason why the J-20 couldn't have a similar intake arrangement closer to the engines.

there is not by my logic, DSI are fixed, the bump creates the shock that impinges upon the cowl lip, the bump also diverts the boundary layer, DSI are designed for a mach number, like any inlet by being fixed only works for a speed range.

DSI are designed to have the least of parts, thus are simplier to build and mantain.

For stealth aircraft they reduce price and maintainance.


China has taken the DSI intakes because allow speeds up to mach 1.8 at very low price and with excellent stealth features.

The rest are pure myths.

i won`t further but if you want to believe there are variable geometry intakes of DSI is up to you, no need to go further, but read about intakes.

fixed intakes are good up to Mach 2, external compression variable geometry intakes are good up to Mach 2.6 and from around mach 3 you can use mixed compression intakes.


If you see that then you will see the fact the DSI on J-20 is fixed and you will realize as the Russians did that the F-22`s caret type air intake is better suited for higher speeds than Mach 2.3

 

[Skywatcher]

there is not by my logic, DSI are fixed, the bump creates the shock that impinges upon the cowl lip, the bump also diverts the boundary layer, DSI are designed for a mach number, like any inlet by being fixed only works for a speed range.

DSI are designed to have the least of parts, thus are simplier to build and mantain.

For stealth aircraft they reduce price and maintainance.


China has taken the DSI intakes because allow speeds up to mach 1.8 at very low price and with excellent stealth features.

The rest are pure myths.

i won`t further but if you want to believe there are variable geometry intakes of DSI is up to you, no need to go further, but read about intakes.

fixed intakes are good up to Mach 2, external compression variable geometry intakes are good up to Mach 2.6 and from around mach 3 you can use mixed or internal compression intakes.


If you see that then you will see the fact the DSI on J-20 is fixed and you will realize as the Russians did that the F-22`s caret type air intake is better suited for higher speeds than Mach 2.3

So you admit that mixing DSI and internal compression intakes does nothing to inhibit speeds above Mach 2.0

Concession accepted.

 

[MiG-29]

So you admit that mixing DSI and internal compression intakes does nothing to inhibit speeds above Mach 2.0

Concession accepted.

you are just fantasizing.

there is no such DSI intake.

A fixed intake as that of J-20 is only good up to Mach 1.8, and saddly for you mixed compression intakes are only used above Mach 2.8 XB-70 used one like that, internal compression requiere lower mach speeds of Mach 2.0 and are very difficult to make and design for such all aircraft use mixed compression variable geometry at Mach 3 in example MiG-31 or SR-71.

So you have a gap of 1200km/h from Mach 1.8 to Mach 2.7 that usually is filled by variable geometry external compression intakes like the one of F-14 or Su-27.

J-20 has fixed DSI intakes you like it or not or you believe or not

 

[Engineer]

there is not by my logic, DSI are fixed, the bump creates the shock that impinges upon the cowl lip, the bump also diverts the boundary layer, DSI are designed for a mach number, like any inlet by being fixed only works for a speed range.

All inlets only work within a certain speed range as designed by the engineers regardless of whether they are fixed or have variable ramps. However, the boundary of speed range is determined by the capabilities of the engineers, not because a certain type of inlet was chosen.

DSI are designed to have the least of parts, thus are simplier to build and mantain.

For stealth aircraft they reduce price and maintainance.


China has taken the DSI intakes because allow speeds up to mach 1.8 at very low price and with excellent stealth features.

DSI is simpler, lighter, cheaper and offers better stealth characteristics. However, DSI has no such speed limit at Mach 1.8 contrary to your claim. Below is an extract from a research paper on J-10B's DSI saying "at Mach 2.0 the pressure recovery ratio reaches 0.87, while at Mach 1.8 this ratio is not lower than 0.91".

When we compare the above numbers to the data points in the graph below, we see that DSI offers the same performance as F-4D's variable geometry inlet at Mach 2.0. When the airspeed is at Mach 1.8, DSI's recovery ratio of 0.91 is clearly better than F-4D's pressure recovery at 0.89.

So, China chose DSI for most of the reasons you stated plus the fact that DSI has similar performance as 3-shock variable geometry inlet.

The rest are pure myths.

i won`t further but if you want to believe there are variable geometry intakes of DSI is up to you, no need to go further, but read about intakes.

fixed intakes are good up to Mach 2, external compression variable geometry intakes are good up to Mach 2.6 and from around mach 3 you can use mixed or internal compression intakes.


If you see that then you will see the fact the DSI on J-20 is fixed and you will realize as the Russians did that the F-22`s caret type air intake is better suited for higher speeds than Mach 2.3

Your statement about fixed inlet only being good up to Mach 2 is incorrect. Firstly, Caret inlet on the F-22 is fixed yet F-22 has a quoted top speed above Mach 2.0. Secondly, fixed inlet also sees application at hypersonic speed which is above Mach 5. Below is a picture of a hypersonic vehicle with fixed inlet being tested at a wind tunnel:

What Russia uses on the T-50 is variable geometry inlet. The funding issue being faced by the Russians means there would be little research devoted to investigation of other type of inlets. So, the choice on T-50 would reflect the Russians' inability to design a fixed inlet with similar performance as that of a variable-geometry inlet.

 

[latenlazy]

you are just fantasizing.

there is no such DSI intake.

A fixed intake as that of J-20 is only good up to Mach 1.8, and saddly for you mixed compression intakes are only used above Mach 2.8 XB-70 used one like that, internal compression requiere lower mach speeds of Mach 2.0 and are very difficult to make and design for such all aircraft use mixed compression variable geometry at Mach 3 in example MiG-31 or SR-71.

So you have a gap of 1200km/h from Mach 1.8 to Mach 2.7 that usually is filled by variable geometry external compression intakes like the one of F-14 or Su-27.

J-20 has fixed DSI intakes you like it or not or you believe or not

And...how do you know the J-20's DSI must be designed for up to mach 1.8?