JF-17 Thunder Multirole Fighter [Thread 4]

[Viper0011.]

First...Lay of the 'sir' stuff.

LOL, I pretty much saw this coming . All of my x-mil home boys also lay low in good old jeans.

Every man has weaknesses. So does every fighter. Whatever advantages that one fighter has over the opponent, each advantage is a rule. This has been proven over and over.

Absolutely agreed. USAF and Israeli air forces specialize in learning the weakness of the enemy and train accordingly. That way, from the beginning it becomes a second nature to situate yourself in a position that will force the enemy to work under your rules. Technology matters but tactics matter a lot more. F-4 is also a great example, the Israelis and the USAF/USN trained extensively to deal with more agile Mig threat. And it worked. F-4 is a massive twin turbine plane and so is F-14.

The technological gap between the fighters you listed are not as great as the examples I gave.

Something that I've been preaching in this thread when folks just blindly say that the SU-30 is the god father of all jets. Entirely ignoring the reality and other factors such as the radar ranges, lock on capability, rcs and missile launching capability. If proper tactics are used, it may turn out to be a better plane BUT, by itself, its just a good plane. There's more to what makes a plane into a successful war machine. F-86 Sabres were very successful against superior Migs, primarily due to their training against where they needed to be when they were to dog fight a Mig and then the tech, i.e. the radar controlled guns.

 

[fatman17]

LOL, I pretty much saw this coming . All of my x-mil home boys also lay low in good old jeans.




Absolutely agreed. USAF and Israeli air forces specialize in learning the weakness of the enemy and train accordingly. That way, from the beginning it becomes a second nature to situate yourself in a position that will force the enemy to work under your rules. Technology matters but tactics matter a lot more. F-4 is also a great example, the Israelis and the USAF/USN trained extensively to deal with more agile Mig threat. And it worked. F-4 is a massive twin turbine plane and so is F-14.




Something that I've been preaching in this thread when folks just blindly say that the SU-30 is the god father of all jets. Entirely ignoring the reality and other factors such as the radar ranges, lock on capability, rcs and missile launching capability. If proper tactics are used, it may turn out to be a better plane BUT, by itself, its just a good plane. There's more to what makes a plane into a successful war machine. F-86 Sabres were very successful against superior Migs, primarily due to their training against where they needed to be when they were to dog fight a Mig and then the tech, i.e. the radar controlled guns.

motto of the PAF - DCAT,DCAT,and then more DCAT.

 

[Bratva]

motto of the PAF - DCAT,DCAT,and then more DCAT.

 

[gambit]

Absolutely agreed. USAF and Israeli air forces specialize in learning the weakness of the enemy and train accordingly. That way, from the beginning it becomes a second nature to situate yourself in a position that will force the enemy to work under your rules. Technology matters but tactics matter a lot more. F-4 is also a great example, the Israelis and the USAF/USN trained extensively to deal with more agile Mig threat. And it worked. F-4 is a massive twin turbine plane and so is F-14.

Speaking of the F-4...

Operation Bolo - Wikipedia, the free encyclopedia

the Phantom suffered from one critical armament weakness – the lack of an internal cannon, as its original conception as a fleet defense interceptor dictated that air combat would occur at beyond visual range with radar-guided missiles. It was also a large, heavy fighter, with high wing loadings that degraded its performance in high-G turns, and with engines that tended to produce large amounts of smoke, making it highly visible in combat.

...the MiG-21 had rapid acceleration, was agile at supersonic speeds and at high altitudes,

...its small size made it difficult to spot even when its adversary was warned of its presence.

...intercepting MiG-21s shot down two F-105s and forced 20% of all strike sorties to jettison their bombloads.

The agility of the MiG-21 and the VPAF tactic of high-speed slashing attacks from astern under GCI control posed a significant challenge to American pilots,...

But what happened after Operation Bolo where the inferior F-4s forced the MIG pilots to fight under the F-4's rules...???

For the North Vietnamese (and their Soviet allies who supplied the MiG-21 aircraft and helped set up the integrated air defense network), the two reverses forced them to husband their assets by grounding the MiGs for several months for retraining and devising of new tactics.

The North Vietnamese Air Force lost half of their -21 force in one engagement. That is a terrible single event combat record for a fighter and the force that flies it.

Operation Bolo shows that technological parity puts a greater demand on the human operator of hardware than previously thought.

 

[abdulbarijan]

As earlier Sancho posted that the intake of the JF-17 is curved inwards and in addition to the Y ducts and the DSI bump this may have an effect on reducing the RCS, I would like to know the thoughts of senior members on this assertion.....

-Is it true, since the intake is curved and has an angle that can cause multiple internal reflections .....

-How much will this help in the frontal RCS aspect since the DSI itself was believed to reduce the RCS by 25-30% or atleast thats what I read in an article...

 

[Last Hope]

The curved intakes perform two functions.

- They basically smoother the airflow in the intakes, towards the engines.
- They also reduce the RCS to certain level.

Another feature is that the streamline shape slightly reduces resistance and allows aircraft to travel with ease and help in manoeuvres. Certain curves on the fuselage and intakes of fighter aircraft gives dynamic strength allowing the aircraft to bear more G force.

 

[gambit]

-Is it true, since the intake is curved and has an angle that can cause multiple internal reflections .....

Yes...But on a single engine aircraft, that intake system curvature is natural anyway and not because of any forethought about RCS control.

-How much will this help in the frontal RCS aspect

The frontal RCS of any aircraft, except prop jobs, is the lowest RCS aspect.

...since the DSI itself was believed to reduce the RCS by 25-30% or atleast thats what I read in an article...

I have a serious problem with that argument and unfortunately to those of us who have relevant experience in this field, that argument have been taken as technical gospel when it should be technical nonsense. Nothing personal to you but to that argument.

By what 'non-DSI' measurements performed and how much to establish an accepted baseline to determine future DSI-ed intake systems? None that am aware of. Any figure of 'reduction' thrown out or threw up by anyone is purely speculative. At least for the frontal RCS value, we have top/bottom to measure against. But for a DSI-ed intake system of any aircraft, have any of its brothers been equipped with a 'non-DSI' intake and RCS measurements performed on both? If the answer is no, then how valid is that claimed reduction figure?

Here is one of my favorite illustrations about radar detection that says so much about the field...

That is what an airliner look like electrically.

The 'floor' is a rejection threshold, meaning signal levels that we discard from display because it is too low. Not because we do not detect them because in radar detection NOTHING is invisible and no self respecting radar engineer will ever say anything is 'invisible'. What we do not 'see' or display on the scope or the graph as above are simply signal strengths that we do not want to 'see' or display.

So for the airliner above, somewhere in that display is a UHF dorsal antenna. But the reason we do not see the antenna is because its reflectivity is MASKED by greater reflecting signals. It does not mean the seeking radar do not detect that little blade antenna. Have no doubt, my friend, it does. But there are larger surfaces and structures whose reflectivity are much greater so the seeking radar have to display those greater signal strengths.

That huge spike in the rear is the vertical stabilator. Now why would I want to reduce the reflectivity of that little UHF blade antenna when there is that huge spike to give me away? It make no common sense, let alone financial sense.

Same argument with a DSI-ed intake and a 'regular' intake.

The above RCS nightmare is going to mask the 'regular' intake so much that the 'regular' intake might as well be a DSI intake. In other words, it does not matter one whit to the enemy's seeking radar if you have a 'regular' intake or a DSI version if you are going to carry all that wing doo-dads from home base to target.

The F-22 does not have a DSI intake system and its RCS is secret unknown.

So please take with a lot of salt anyone from any forum saying a DSI intake system 'reduces' the RCS of this or that fighter by X or Y percentage. Ask reduced from what baseline and ask for sources of that baseline. You will find the guy start sputtering and stuttering on how he came to that conclusion.

 

[alimobin memon]

For example F35 has DSI but when it adds pylons for bigger payload it loses it's stealth capabilities so in case of jf17 only empty jf17 with DSI gives a good effect otherwise when it is fully loaded i dont see any RCS reduced advantage to jf17.

 

[gambit]

For example F35 has DSI but when it adds pylons for bigger payload it loses it's stealth capabilities so in case of jf17 only empty jf17 with DSI gives a good effect otherwise when it is fully loaded i dont see any RCS reduced advantage to jf17.

Only when the situation either have a reduced need for low radar observability or none at all.

A clean F-35 is not unarmed while a clean JF-17 is unarmed.

 

[abdulbarijan]

Only when the situation either have a reduced need for low radar observability or none at all.

A clean F-35 is not unarmed while a clean JF-17 is unarmed.

Simple question : Does DSI have RCS advantages over conventional intakes as it hides fan blades better....also i would like to correct my previous statement...It said

It redirects unwanted boundary layer airflow away from the inlets, essentially doing the job of heavier, more com*plex, and more costly approaches being used for because intake is one of the three major forward scatters of an aircraft (30%-35% contribution to aircraft forward Radar Cross Section (RCS)).

I misread it somehow ...

 

[gambit]

Simple question : Does DSI have RCS advantages over conventional intakes as it hides fan blades better....also i would like to correct my previous statement...It said



I misread it somehow ...

And am trying to tell ya...It is NOT a simple issue.

It may be a simplistic question, but that does not mean the issue itself is simple.

Let us take the RCS related sentence from wherever you got it...

...because intake is one of the three major forward scatters of an aircraft (30%-35% contribution to aircraft forward Radar Cross Section (RCS)).

You should try to understand the concepts of threshold and contributorship in radar detection.

A threshold is an arbitrary line where you want to do <something> to whatever it is that trespass that line. Your patience have a threshold. The blood alcohol level that get you arrested is a threshold.

A contributorship is about giving to a greater whole from being a part or member of that whole. Your taxes constitute a contributorship to the country's budget. Your car's exhaust is a contributorship to the ozone destroying chemicals.

It is no different in radar detection where each of your arms is a contributor to your body's total RCS value if the radar sees them. If you turn sideways then one arm, one ear and one leg would not be contributors to your body's total RCS value. This is because in radar detection, RCS depends on the observer as much as the target. So if the observer cannot see a physical structure, such as your arm or your ear, then as far as it goes, that structure does not exist.

So as a standalone structure, the DSI intake assembly does have a lower contributorship than the 'regular' intake system. But that is not how radar detection exclusively works. In radar data processing, the largest contributorship will be the main focus of the radar, so if the cockpit well area, which is a resonator chamber, is a greater contributorship than the sharp plates and angles of the 'regular' intake system, then the cockpit will be the guide for the seeking radar. Remove the 'regular' intake and substitute in a DSI will do nothing to help. That is like cutting off one ear and/or your nose and hope that your father will no longer recognize his son.

In RCS control, and I hesitate to use the word 'reduction', the goal is to reduce the largest contributor to below the second largest, which became the largest, and the tedious work continues that way until whatever largest contributor that remain cannot be reduced any more. At that time, any other work on any other contributor is quite redundant and very well financially troublesome. At that point, we take measurement of the WHOLE aircraft and give it an average RCS value as well as many RCS values based upon precise viewing angles.

If you want to know how tedious, technically difficult and costly it is...

Benefield Anechoic Facility - Wikipedia, the free encyclopedia

Benefield Anechoic Facility (BAF) is an anechoic chamber located at the southwest side of the Edwards Air Force Base main base. It is currently the world's largest anechoic chamber. [1][2] The BAF supports installed systems testing for avionics test programs requiring a large, shielded chamber with radio frequency (RF) absorption capability that simulates free space.

It is only in an EM isolated chamber can you find the true radar cross section (RCS) of any complex body, from the human body to a bicycle to a jet fighter.

That is why it is highly misleading to focus on the DSI intake system and somehow magically empower that structure with miraculous RCS reduction properties. That is just simply not how radar detection works. I understand I am severely outnumbered by those who are misled and became proponents of that argument but that does not mean I should stand idle while falsehoods are being tossed about. The silent readers deserve a rebuttal.

 

[Last Hope]

Simple question : Does DSI have RCS advantages over conventional intakes as it hides fan blades better....also i would like to correct my previous statement..

Yes it does, it surely does. But I cannot say the level of RCS drop, it could be major or even minor degree of reduction.

 

[gambit]

Using the DSI intake to hide the fan blades is equally dubious an argument.

It is extremely rare -- but not improbable -- that a radar will look straight down the intake where the fan blades' reflectivity overwhelms the inlet lips and everything else in the area. That kind of direct view, literally collision course, does not last long and when both radar and target deviate, it will be the inlet structure itself with its plates and flat surfaces that will be the greater contributor. No longer the fan blades.

The reason why the F-22 have the serpentine intake system to hide the fan blades even in such a direct view situation is because the F-22 was design from the start to have RCS control measures built in, aka shaping. That mean if the F-22 does not have that serpentine intake system, the fan blades will be that overwhelming contributor because the rest of the body are shaped to control reflectivity. Lockheed figured all this out a long time ago and the result is the F-22's serpentine intake system.

For an aircraft that was not designed with RCS control measures in mind, hiding the fan blades via DSI for fear of that extremely rare direct view situation does not make logical sense. Missile's radar can lock on with far less reflectivity.

 

[Viper0011.]

Using the DSI intake to hide the fan blades is equally dubious an argument.

It is extremely rare -- but not improbable -- that a radar will look straight down the intake where the fan blades' reflectivity overwhelms the inlet lips and everything else in the area. That kind of direct view, literally collision course, does not last long and when both radar and target deviate, it will be the inlet structure itself with its plates and flat surfaces that will be the greater contributor. No longer the fan blades.

Absolutely. The DSI in this case (from a design perspective) are just added to increase the aerodynamic capability of the plane and the recovery between subsonic to supersonic and then back. It doesn't help with stealth. LM used it in F-16's too at some point for test bed evaluation of DSI.

In addition to what Gambit said, fan blades also produce radiation / energy when they are active due to extreme circular movement. Radars love energy producing surfaces as they are easily identifiable. In fact heat seeking missiles use a plane's energy / heat to lock onto it. So unless you design RCS reduction measures in the design like Gambit said, it's hard to control rcs when energy is being produced. There is currently no way to cool that energy off in JFT and turn it into low density low profile energy that may be lesser than Radar's inbound beam. Raptor has certain features to cool off internal energy in certain cases

 

[graphican]

Thanks for such a useful post.

In your opinion what is the least achievable RCS for a fighter like JFT. Just a wise guess would help.

If possible for you to answer, may I request to know what makes Russian PAK-FA a stealth if they are not using serpentine or any similar intake system? Does that means PAK-FA will have an extremely high RCS at some angle?