J-10 Thread III (Closed to posting)

[i.e.]

1) I did not say it was a four shock intake.
2) Not all four shocks need to be generated by the bump
3) You don't always need four shocks to get a good pressure recovery at high mach. It's dependent on the discrete geometry of the inlet, the tunnel, and as ie mentioned, even structures in front of the inlet.

shocks are generated by the combination of inlet entrance geometry and inlet internal geometry.

I can have a pitot intake but with plenty of oblique shocks generated by internal geometry, before the air hits the intake.

or I can have the forebody generate a compression so that my pressure before fan vs freeair still has a decent ratio with a very simple intake design. hint hint f-16.
it;s the total that counts not the specific parts.

 

[Hyperwarp]

Mig-29 is Mig-33MLD on defencetalk

...

I think you mean MiG-23MLD? MiG-23MLD/Flogger @ Keypubs IS MiG-29. He himself clearly stated that at this forum IIRC.

but,...

...and probably JSR on Keypub

No! JSR @ Keypubs is suspected to be Star49 who was banned at keypubs (and subsequent accounts by Star49). He went silent for while, but seems to be back...

PS: my apologies for this OT post...

 

[MiG-29]

1) I did not say it was a four shock intake.
2) Not all four shocks need to be generated by the bump
3) You don't always need four shocks to get a good pressure recovery at high mach. It's dependent on the discrete geometry of the inlet, the tunnel, and as ie mentioned, even structures in front of the inlet.

intakes have shocks generate in different ways, some are external and internal compression, others generate normal and oblique shock on the ramp and intake cowl, however you always slow down the flow because modern turbofans need airflow at Mach 0.6-0.9 to work.

Sometimes the fore fuselage it self can slow the flow by creating shocks, however there are prices to pay in drag, so engineers will use intakes like the one of F-14 or SR-71

for every 1% loss in pressure represents an equal or greater loss in thrust at static conditions and a proportionately higher loss at forward speed. Typically, at Mach 2.2 an 8% loss in pressure recovery reduces net thrust by 13% and increases specific fuel consumption by 5%.


So now tell me why 87% pressure recovery loss is an acceptable number?

If J-10B has a DSI that at Mach 2 has a pressure recovery of 87% it means its Al-31 or WS-10 will have huge losses in thrust in the range of 20% or more and very high increases in SFC

Add to add loses in payload speed and range.

 

[MiG-29]

shocks are generated by the combination of inlet entrance geometry and inlet internal geometry.

I can have a pitot intake but with plenty of oblique shocks generated by internal geometry, before the air hits the intake.

or I can have the forebody generate a compression so that my pressure before fan vs freeair still has a decent ratio with a very simple intake design. hint hint f-16.
it;s the total that counts not the specific parts.

DSI is fixed, hint hint external-internal compression on a variable geometry intake

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hint hint fuselage compression

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hint hint

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this type of intake is only good for speeds bellow Mach 1.5, no Mach 3, Mach 2.3 fighter or bomber uses a pitot tube intake, hint hint you need a cone like on the SR-71 with Multi shock compression for Oswatisch optimization.

 

[Engineer]

Let me explain you.

Any Engine has pressure recovery loss tolerance, however if you want less breakdowns, malfunctions and lower and cheaper maintainace then you need the highest pressure recovery percentage, why? can the J-10B fly at mach 2? probably yes, the F-16 did it with DSI, but the problem arises at maintainace and reliability, thus F-35 is kept at its more effective and reliable Mach number 1.6, can it fly faster? yes as long as the airframe and engine combination allows it (in few words if at 87% or lower thrust the aircraft can achieve Mach 2), but the engine will suffer from engine stalls to engine surges, thus due to lower thrust and lower relaibility, engines are provided with variable geometry intakes.

87% is a low number at Mach 2, it means you are not only lowering the thrust of the engine but also lowering the safety margin to operate it.

In a fighter that rarely will venture into Mach 2 or Mach 2.2 well it is okay to have DSIs.
To operate the J-10B at a safety margin under operational conditions then you need 95% pressure recovery.

Which we know is complete B.S. because from the

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, not even F-15 achieves 0.95 pressure recovery coefficient at Mach 2.0.

As such saying the original J-10 has a F-4D type of intake is to say the Chinese designed a less effective fighter than the MiG-29 or Mirage 2000, thus it is even illogic to say the 3 shock intake of the J-10 has equal performance to a 1950s jet is just an insult to Chinese designers.

Ah, but the fact is J-10's intake and F-4D's intake are in the same class, as both of them produce 3 shocks. You stated and I quote:

Intakes are devided by two main criteria:

Number of oblique or normal shocks they create and position.

Are you now not following the rules for intake classification? And if we were to take values from Wikipedia as truth and look at the top speed for the two aircraft, we will see that F-4E has a maximum speed of M2.23 and J-10 has a maximum speed of M2.2. This is not a coincident, as both aircraft shares the same type of intakes. And since the

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shows that F-4D can travel at M2.0 even with pressure recovery coefficient at 0.87, and that F-16 pressure recovery coefficient is only 0.8 at M1.7, we see that your requirement of 0.95 is complete cow manure.

The original J-10A must have a really good pressure recovery in order to make it fly with a variable geometry intake otherwise a Lavi or F-16 intake is better.

You messed up the cause and effect here. J-10A has variable geometry intake thus get better pressure recovery coefficient than Lavi and F-16. Now, the real question is whether J-10B can travel at M2.0. You said no which you are yet unable to prove.

You can continue thinking the DSI will allow Mach 2 without affecting the engine effective service life and maintainability, it is more realistic to say if the J-10B ever goes Mach 2 will be very rarely, a more practical Mach 1.8 is a realistic number, fighters like Rafale or F-18 do it for such a reason.

Complete strawman. You are unable to prove that J-10B is unable to travel at M2.0, and now you are attempting misdirection. Latenlazy never made any claims regarding engine service life and maintainability.

 

[Engineer]

So now tell me why 87% pressure recovery loss is an acceptable number?

It isn't 87% loss, since 100 - 87 = 13. But tell me why 0.87 pressure recovery coefficient is unacceptable when the engineers that designed the aircraft found it perfectly acceptable to make their aircraft capable of going at these speed despite the loss.

If J-10B has a DSI that at Mach 2 has a pressure recovery of 87% it means its Al-31 or WS-10 will have huge losses in thrust in the range of 20% or more and very high increases in SFC

Add to add loses in payload speed and range.

So you go around in circles but still have no proof whatsoever that says aircraft with DSI cannot travel at Mach 2.0. Why am I not surprise?

All types of intake encounter pressure recovery loss as speed increases; it isn't a phenomenon unique to the J-10. This is also the reason why cruise speed (use at most time) is lower than top speed (use in dire circumstances).

 

[latenlazy]

intakes have shocks generate in different ways, some are external and internal compression, others generate normal and oblique shock on the ramp and intake cowl, however you always slow down the flow because modern turbofans need airflow at Mach 0.6-0.9 to work.

Sometimes the fore fuselage it self can slow the flow by creating shocks, however there are prices to pay in drag, so engineers will use intakes like the one of F-14 or SR-71

for every 1% loss in pressure represents an equal or greater loss in thrust at static conditions and a proportionately higher loss at forward speed. Typically, at Mach 2.2 an 8% loss in pressure recovery reduces net thrust by 13% and increases specific fuel consumption by 5%.


So now tell me why 87% pressure recovery loss is an acceptable number?

If J-10B has a DSI that at Mach 2 has a pressure recovery of 87% it means its Al-31 or WS-10 will have huge losses in thrust in the range of 20% or more and very high increases in SFC

Add to add loses in payload speed and range.

To add to what Engineer pointed out, did I say an 87% pressure recovery is or isn't acceptable? I used the study with 87% to point out how not all DSIs have the same pressure recovery number (which goes to my point about not all DSIs have the same geometry and therefore same results) because you were going around touting another study that showed a sub 80% pressure recovery number and acting as if all DSIs were limited to that. Reading comprehension man.

Nothing has indicated that the J-10B's pressure recovery is 87% at mach 2, or even that its DSI alone has a pressure recovery of 87% at mach 2. Unless we go with the number Engineer provided us (which touts pressure recovery approaching 90%) we don't have any other published numbers regarding the matter.

The main point of criticism here is that your assertion that all planes with a DSI are limited to mach 2 is a gross oversimplification. Nothing says a plane that uses a DSI can only use a DSI to generate compression. The DSI is one of many instruments and techniques, and any plane will use a collection of these to achieve the desired result. Therefore it's impossible and silly to conclude that the J-10B must not be optimized beyond Mach 2. Maybe it isn't, and maybe it is, but drawing that conclusion simply because it has a DSI is sloppy thinking.

 

[i.e.]

DSI is fixed, hint hint external-internal compression on a variable geometry intake

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hint hint fuselage compression

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hint hint

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this type of intake is only good for speeds bellow Mach 1.5, no Mach 3, Mach 2.3 fighter or bomber uses a pitot tube intake, hint hint you need a cone like on the SR-71 with Multi shock compression for Oswatisch optimization.

you don't need to pass these useless hints.

F-16 Uses forebody compression and its clean config MMo is Mach 2. although rarely exercised.

just let you know F-16's intake is a pitot intake. J-10's initial intake design was very much modeled after F-16's with a boudray layer seperator lip extended forward little bit more to deal with forebody distortions.

enough is enough, I really don't think you know what you are talking about.

things are more complicated than what you made them out to be.

 

[i.e.]

To add to what Engineer pointed out, did I say an 87% pressure recovery is or isn't acceptable? I used the study with 87% to point out how not all DSIs have the same pressure recovery number (which goes to my point about not all DSIs have the same geometry and therefore same results) because you were going around touting another study that showed a sub 80% pressure recovery number and acting as if all DSIs were limited to that. Reading comprehension man.

Nothing has indicated that the J-10B's pressure recovery is 87% at mach 2, or even that its DSI alone has a pressure recovery of 87% at mach 2. Unless we go with the number Engineer provided us (which touts over 90% pressure recovery) we don't have any other published numbers regarding the matter.

The main point of criticism here is that your assertion that all planes with a DSI are limited to mach 2 is a gross oversimplification. Nothing says a plane that uses a DSI can only use a DSI to generate compression. The DSI is one of many instruments and techniques, and any plane will use a collection of these to achieve the desired result. Therefore it's impossible and silly to conclude that the J-10B must not be optimized beyond Mach 2. Maybe it isn't, and maybe it is, but drawing that conclusion simply because it has a DSI is sloppy thinking.

Just to add.

Caret intake on F22 is a fixed geometry intake.

If you want to talk fixed geometry intake can not go to the speed....

and then what is the top speed of F22?

care to guess what is the top speed YF23? whatever it is it prob has a higher MMo than YF22. and guess what it has fixed intake geometry too.

most of the shock interactions happens inside of the intake duct anyways, what's going on after the mouth of the inlet has more to do pressure recovery.

DSI does boundary layer blowing and some shock generation, and deals with alphabeta distortions..

but it doesn't determine the entire shock geometry nor does it take care of the entire pressure recovery

 

[MiG-29]

To add to what Engineer pointed out, did I say an 87% pressure recovery is or isn't acceptable? I used the study with 87% to point out how not all DSIs have the same pressure recovery number (which goes to my point about not all DSIs have the same geometry and therefore same results) because you were going around touting another study that showed a sub 80% pressure recovery number and acting as if all DSIs were limited to that. Reading comprehension man.

Nothing has indicated that the J-10B's pressure recovery is 87% at mach 2, or even that its DSI alone has a pressure recovery of 87% at mach 2. Unless we go with the number Engineer provided us (which touts pressure recovery approaching 90%) we don't have any other published numbers regarding the matter.

The main point of criticism here is that your assertion that all planes with a DSI are limited to mach 2 is a gross oversimplification. Nothing says a plane that uses a DSI can only use a DSI to generate compression. The DSI is one of many instruments and techniques, and any plane will use a collection of these to achieve the desired result. Therefore it's impossible and silly to conclude that the J-10B must not be optimized beyond Mach 2. Maybe it isn't, and maybe it is, but drawing that conclusion simply because it has a DSI is sloppy thinking.

Man you are just speculating, if the J-10B tries to go Mach 2.3, it will damage its engines plus will spend more fuel, in fact a detail, the Mirage 2000 has lower thrust to weight ratio than the F-16 but it achieves Mach 2.2, the F-16 in the other hand having higher thrust to weight ratio achieves Mach 2.

MiG-25 achieves Mach 2.8 having lower thrust to weight ratio than F-16, but the MiG-25 has better inlets.

the F-14 is the same, it will go to Mach 2.34 having lower thrust to weight ratio.

So you can not expect the J-10B will achive Mach 2.3 because it will reduce its thrust more than an F-14 and will generate more engine stalls and purges.



The problem is not only the reduced thrust but the damage you inflict into the engines, no F-16 pilot can achieve Mach 2.34 because it will damage the F-100s, the F-15 can go Mach 2.5 because the variable geometry intake protects the engines and can use more the total thrust it can generate.


Variable geometry intakes in fact all intakes have improvements but definitively DSI achieves its best near Mach 1.2 and Mach 1.7 is the design limit for the intake.

Mixed compression is used on Sukhoi T-4 but it also pays in drag and has variable geometry to reflect the shocks generated.