J-10 Thread III (Closed to posting)

[MiG-29]

Don't get snarky.

I mentioned fueslage compression because it is one of the things (that amongst many) that you neglected to mention with your insistence that only a variable geometry intake can go mach 2.

it;s not trivial either in case of f-16.

and...

I really want to see how you look at F-22 with its fixed geometry caret intake...
or even the YF-23.

another "slow" design perhaps.

come on, I am waiting to see whatelse you gonna pull out...

Does the YF-23 have a DSI? the YF-23 uses the wing leading edge as the wedge-ramp of some 2D intakes, and since it has no fuselage boundary layer above the wing it does not need splitter, but as the intake of the F-4 or F-15 internal holes are drilled to get rid of the little boundary generated inside the intake.
the YF-23 has a wide separation from the main fuselage, this keeps the lateral boundary layer generated by the fuselage away from the intake, however they are similar to the YF-22 intakes and are fixed.


Speed the YF-23 as F-22 are Mach 2 fighters, not Mach 2.5 or 2.2, physics are universal.

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[i.e.]

Does the YF-23 have a DSI? the YF-23 uses the wing leading edge as the wedge-ramp of some 2D intakes, and since it has no fuselage boundary layer above the wing it does not need splitter, but as the intake of the F-4 or F-15 internal holes are drilled to get rid of the little boundary generated inside the intake.
the YF-23 has a wide separation from the main fuselage, this keeps the lateral boundary layer generated by the fuselage away from the intake, however they are similar to the YF-22 intakes and are fixed.


Speed the YF-23 as F-22 are Mach 2 fighters, not Mach 2.5 or 2.2, physics are universal.

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once again you entirely missing the point.
it's really two questions:
boundry layer control and shock for pressure recovery.

your argument has been that DSI can't do good pressure recovery above certain mach number (1.6M +) . you hinges your argument all on the examples where variable geometry inlets are used for other supersonic fighters who intend to spend more time in the right side of flight envelope.

But... guess what.
YF-23 and F-22 has fixed geometry inlets, they do shock and pressure recovery fine. ah. but some how you still manage to drag boundray layer control into this because it has little to do with pressure recovery via shock geometry.


btw, the LM spec says Mach 2 class .

so you are saying a fixed geomtry inlet fighter can fly at M2 no problem?


...
and you need to find a more authoritative source for YF-23 Speeds otherthan fan boy sites.

 

[MiG-29]

once again you entirely missing the point.
it's really two questions:
boundry layer control and shock for pressure recovery.

your argument has been that DSI can't do good pressure recovery above certain mach number (1.6M +) . you hinges your argument all on the examples where variable geometry inlets are used for other supersonic fighters who intend to spend more time in the right side of flight envelope.

But... guess what.
YF-23 and F-22 has fixed geometry inlets, they do shock and pressure recovery fine. ah. but some how you still manage to drag boundray layer control into this because it has little to do with pressure recovery via shock geometry.


btw, the LM spec says Mach 2 class .

so you are saying a fixed geomtry inlet fighter can fly at M2 no problem?


...
and you need to find a more authoritative source for YF-23 Speeds otherthan fan boy sites.

Let us go by parts, the F-22 has a fixed geometry intake, you can not ask of it going Mach 2.5 or 2.6, it won`t achieve those speeds, the jet by saying Mach 2 class means its max speed is Mach 2, there is no mystery, its caret intake is aerodynamically fine, there is no problem on it like F-16 can achieve Mach 2, does it mean it break laws of physics? no it does not.

Now for the DSI, you have advantages and disadvantage, it brings cheaper costs and cheaper stealth, but because it has fixed cowl and bump, generate less shocks than a variable geometry intake.

Now the F-16 is a Mach 2 jet just in paper, it is more a Mach 1.8 jet, however you have to consider engine tolerance to surge and blade stall.
On fighters like F-18 and Rafale the manufacturer set an operational safety limit of Mach 1.8, can they go Mach 2? yes, they can as long as the thrust of the engine is enough to propel the jet to that speed without surge.

The F-22 is not different, it has the same limits of the other jets, but it is considered safe to fly mach 2 for the F-119 but the reality the F-22 is to fly slower but at supercruise speeds, with a short dash at Mach 2 but flying at 2000km/h or 1.5+ most of the time.

Now a variable geometry intake by the virtue of having the ability of generating 3 or 4 shocks is able to increase the pressure recovery coefficients to levels where it will allow lower thrust loses, cheaper maintainance, higher reliability, and longer engine life.

However the variable geometry has so many moving parts that requiere more RAM to reduce radar signature, so the F-22 and YF-23 skip it its use.

On the J-10 or JF-17, its use is more about price rather than stealth, however the DSI decreases radar signature on the J-10B by having no moving parts.

So the DSI was chosen for the F-35, however the F-35 is a single engine jet that requieres higher relaibility if it is going to fly from a carrier or do VSTOL.
The US navy wanted a twin engine, but got a single engine jet.

J-10B is not different, to risk a single engined fighter with engine surge and reduce its reliability just for the sake of Mach 2, is senseless.


So i see more likely the jet flies slower but safer with the advantage of better stealth, cheaper maintainance and lower manufacturing costs.

 

[paintgun]

that's a better argument from you Mig-29, explains your point of view

M1.6-M1.8 might be a more tolerable 'max speed' zone for these fighters we have been discussing, or rather these jets are designed to perform on this 'max speed'

 

[A.Man]

The Airshow!

[video]http://v.ifeng.com/mil/mainland/201111/083563d4-0d3a-4a19-86ef-3f4cdee3693d.shtml[/video]

 

[Engineer]

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.

First, there is no reason why J-10B needs to fly at M2.3 to prove DSI can allow the plane to reach M2.0. A J-10B reaching J-10A's top speed (M2.2) already debunks your argument.

Secondly, your assumption that J-10B flying at M2.3 will get more reduced thrust than F-14 is just an assumption and totally unsubstantiated. Forget J-10B, there is no evidence whatsoever that says J-10A can even go at that speed.

Third, there is no evidence supporting your claim that reaching M2.0 would damage J-10B's engine. You are assuming that J-10B cannot reach M2.0 due to engine limit to argue that J-10B cannot reach M2.0, which is

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.

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.

This has no relevance to J-10.

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.

There is no proof saying that being the case. In fact, a pressure recovery coefficient of 0.87 quoted at M2.0 already says that DSI can allow the plane to achieve M2.0, which is a proof which debunks your claim.

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

This is irrelevant to J-10.

 

[Engineer]

Now a variable geometry intake by the virtue of having the ability of generating 3 or 4 shocks is able to increase the pressure recovery coefficients to levels where it will allow lower thrust loses, cheaper maintainance, higher reliability, and longer engine life.

Actually, the complexity of variable geometry suggests more expensive maintenance and lower reliability due to more mechanical components/moving parts. Citation is needed on your claim that variable geometry inlets extend engine life compared to fixed inlets.

J-10B is not different, to risk a single engined fighter with engine surge and reduce its reliability just for the sake of Mach 2, is senseless.


So i see more likely the jet flies slower but safer with the advantage of better stealth, cheaper maintainance and lower manufacturing costs.

That's wishful thinking on your part rather than fact. Let's look at the graph again:

The pressure recovery coefficient for F-104 is ~0.8 at M2.0. For F-105, it is 0.85 at M2.0. For F-4D, it is 0.87 at M2.0. Finally, the pressure recovery coefficient of F-16 is at 0.8 around M1.8. The quoted pressure recovery coefficient for DSI at 2005 is 0.87 at M2.0.

It is senseless to suggest that with higher pressure recovery coefficient (0.87), the J-10B can't fly at the speed of the aircraft that have lower pressure recovery coefficient.

 

[MiG-29]

that's a better argument from you Mig-29, explains your point of view

M1.6-M1.8 might be a more tolerable 'max speed' zone for these fighters we have been discussing, or rather these jets are designed to perform on this 'max speed'

Mach 1.6-1.8 is a more tolerable and efficient speed, the Rafale for example has a intake capable of Mach 2, however it flies at mach 1.8, the reason is efficiency.
An expert in experimental aerodynamics, he was one of the inventors of the Rafale air intake, the first to be capable of achieving Mach 2 flight without the need for any additional devices

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At 100% pressure recovery the jet has a static thrust of 100%, what does it mean?
It means the Al-31 delivers its 12500kg of thrust, but at .95, that falls between 11900kg thrust to 11700kg of thrust, at .87, that falls even lower between 10900kg thrust and 10400kg of thrust.

Now make the numbers if your J-10B is flying fully loaded, then you need to burn more fuel to get the same thrust of lower speeds, also it means your engine is struggling more.


On fighters like F-4 you see relatively low numbers but here is the clue, the F-14 and F-15 that replaced it, fly at almost the same speed but have higher pressure recovery, better performance, payload and agility and more efficient SFC, so they do not spend as much fuel as the F-4.

So If you want to get a let us say 1:1 Thrust to weight ratio, you need a lighter jet, but remember as thrust goes down also speed, so you are spending more fuel just to try to keep up with the thrust needs.

So ideally a fighter has a 100% pressure recovery and that is around Mach 1 or bellow, if you remember the F-16 is a dogfighter designed to fly at Mach 0.8 most of the time.


Rafale as F-18 fly slower than the F-16 simply to save fuel and increase payload that translate into longer range, lower maintainance and cheaper operation for the engine, it means also longer service life.

Now if you want a fighter that will fly Mach 2.35 like the MiG-29 or F-14 then you need a a multishock ramp.



A rule of thumb often used is that 1% pressure loss reduces
thrust by 1%, but it became clear early on that the thrust loss
caused by pressure losses in supersonic flight increases
nonlinearly. For example, at a flight speed of Mach 2.2, a
typical engine losing 8% of the free stream total pressure
through the intake will suffer a reduction in thrust of 13% and a
5% increase in fuel consumption [1].

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[Pointblank]

Let us go by parts, the F-22 has a fixed geometry intake, you can not ask of it going Mach 2.5 or 2.6, it won`t achieve those speeds, the jet by saying Mach 2 class means its max speed is Mach 2, there is no mystery, its caret intake is aerodynamically fine, there is no problem on it like F-16 can achieve Mach 2, does it mean it break laws of physics? no it does not.

Now for the DSI, you have advantages and disadvantage, it brings cheaper costs and cheaper stealth, but because it has fixed cowl and bump, generate less shocks than a variable geometry intake.

Now the F-16 is a Mach 2 jet just in paper, it is more a Mach 1.8 jet, however you have to consider engine tolerance to surge and blade stall.
On fighters like F-18 and Rafale the manufacturer set an operational safety limit of Mach 1.8, can they go Mach 2? yes, they can as long as the thrust of the engine is enough to propel the jet to that speed without surge.

The F-22 is not different, it has the same limits of the other jets, but it is considered safe to fly mach 2 for the F-119 but the reality the F-22 is to fly slower but at supercruise speeds, with a short dash at Mach 2 but flying at 2000km/h or 1.5+ most of the time.

Now a variable geometry intake by the virtue of having the ability of generating 3 or 4 shocks is able to increase the pressure recovery coefficients to levels where it will allow lower thrust loses, cheaper maintainance, higher reliability, and longer engine life.

However the variable geometry has so many moving parts that requiere more RAM to reduce radar signature, so the F-22 and YF-23 skip it its use.

On the J-10 or JF-17, its use is more about price rather than stealth, however the DSI decreases radar signature on the J-10B by having no moving parts.

So the DSI was chosen for the F-35, however the F-35 is a single engine jet that requieres higher relaibility if it is going to fly from a carrier or do VSTOL.
The US navy wanted a twin engine, but got a single engine jet.

J-10B is not different, to risk a single engined fighter with engine surge and reduce its reliability just for the sake of Mach 2, is senseless.


So i see more likely the jet flies slower but safer with the advantage of better stealth, cheaper maintainance and lower manufacturing costs.

The amount of time today's fighters spend at their top design speed is an incredibly small fraction of the service life of a fighter jet. On the F-15, the amount of time the entire world fleet has spent anywhere near its top speed is measured in minutes, and most of the supersonic flights were in fact during specialized flights such as Functional Check Flights. The F-15 has NEVER exceeded Mach 1.2 in combat situations because of the drag imposed by the externally mounted weapons and fuel tanks. On the F-16, it can do Mach 2+, but how often do they go that fast? How long can it fly that fast at a fuel consumption rate of almost 50K-lbs+ of fuel per hour at full throttle with afterburners? Hint: No more than 10 minutes.

Transonic acceleration is much more relevant to a fighter pilot than the absolute max speed of the jet.

 

[HKSDU]

I wouldn't mind reading this, but can it go on a separate thread? Every time I see a post on this thread I thought it was some new stuff about the J-10, but it ends not.