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#341 glenn239

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Posted Yesterday, 12:03 PM

A77 It will be hard to hit something if the radar is 250 nm away the target will be under the radar horizon.

 

 

 

If the target uses the horizon to block the radar, the battery has to rely on the missiles' active radars to complete the engagement.  If these are still too far for lock on at the moment LOS is blocked then the battery either has to “guess” where the plane will be, or it needs to rely on other elements in the air defense network to provide mid-course guidance.   Either is probably less certain than a direct LOS, so the plane presumably wants to use the horizon for protection if it can.   



#342 glenn239

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Posted Yesterday, 12:32 PM

Josh We also haven't touched upon the fact that fighter air intercept radars are size limited and need to generate target tracks - at the moment we're generally talking about the X band where low RCS fighters are optimized.

 


My hunch would be that if an SU-35 that gets into an engagement with an F-22, it’s not doing what it’s supposed to be doing.    NATO has maybe 10,000 planes that SU-35 can fight and maybe 300 planes it can’t.  So, your average Russian pilot’s job will be to know when to run away and know when to press the attack.  Failure to know which will lead to either missed opportunities or being killed. 



#343 Josh

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Posted Yesterday, 01:40 PM

It seems highly unlikely the Su-35 would be given a choice or any warning if an F-22 was in theater.

#344 glenn239

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Posted Yesterday, 02:15 PM

In Red Flag the F-15's have to try and engage the F-22's and they get slaughtered.  An SU-35 that wants to live will bolt for the exits the minute the F-22 is picked up by low frequency radar. 

 

Can an F-22 choose to be radar reflective, to lure the SU-35 in to a fight, then become stealthy at the flick of a switch, when the SU-35 can no longer escape?  That would be an interesting question.



#345 GARGEAN

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Posted Yesterday, 03:23 PM

It seems highly unlikely the Su-35 would be given a choice or any warning if an F-22 was in theater.

You should not underestimate it. N035 is VERY powerful radar, and it can be able to catch F-22 from some decent ranges, at least not from perfect front. Plus IRTS cound provide some close warning capability.



#346 GARGEAN

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Posted Yesterday, 03:36 PM

In Red Flag the F-15's have to try and engage the F-22's and they get slaughtered.  An SU-35 that wants to live will bolt for the exits the minute the F-22 is picked up by low frequency radar. 

 

Can an F-22 choose to be radar reflective, to lure the SU-35 in to a fight, then become stealthy at the flick of a switch, when the SU-35 can no longer escape?  That would be an interesting question.

Well, theoretically it can mount Frenel lense in some retractable mount that can be hided into body when needed. Not so much work. Or just fly with open weapon bays, lol.



#347 Josh

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Posted Yesterday, 03:43 PM

It seems highly unlikely the Su-35 would be given a choice or any warning if an F-22 was in theater.

You should not underestimate it. N035 is VERY powerful radar, and it can be able to catch F-22 from some decent ranges, at least not from perfect front. Plus IRTS cound provide some close warning capability.


I'm not saying its a bad aircraft or radar, but the F-22 would pretty much always see the Su-35 before the Su-35 saw the F-22 and the F-22's high altitude performance is such that the Su would have a hard time disengaging.

#348 Josh

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Posted Yesterday, 03:45 PM

In Red Flag the F-15's have to try and engage the F-22's and they get slaughtered.  An SU-35 that wants to live will bolt for the exits the minute the F-22 is picked up by low frequency radar. 
 
Can an F-22 choose to be radar reflective, to lure the SU-35 in to a fight, then become stealthy at the flick of a switch, when the SU-35 can no longer escape?  That would be an interesting question.

Well, theoretically it can mount Frenel lense in some retractable mount that can be hided into body when needed. Not so much work. Or just fly with open weapon bays, lol.


There definitely are radar reflectors that can be put on the aircraft, though I don't think they can be detached in flight. The spread spectrum radar could be employed as a blip enhancer instead of a jammer across the frontal arc, but I'm not sure there's a scenario where this would truly be useful. If the MiGs and Su's go home, then air superiority accomplished.

Edited by Josh, Yesterday, 03:45 PM.


#349 glenn239

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Posted Yesterday, 03:51 PM

Jaro You cannot overcome laws of physics... and radar equation is just that... a physics... there is no miraculous technology that will make stealth obsolete, all "stealth killer" technologies come with huge downsides and constrains people promoting them completely ignore...

 

 

From what I understand from Ben Rich's book, stealth works in two dimensions - to the front, sides or back.  It does not work up and it does not work down.   How do I know that?  Because Ben Rich says the surface has to be angled back 70 degrees from the emitter, and any plane’s topside or belly is a flat radar reflector.   The plane uses a SAM map to weave a path between radars, such that the defending batteries are never close by.  Directly below is dangerous because the belly of the plane allows a lock on – don’t ever fly over a SAM battery.

 

So what S-400 appears to do is use a low frequency radar to get a general location of the stealth aircraft (within an area of uncertainty of a few miles).  It then it fires one or more very expensive active radar homing missiles in ballistic trajectories to the area of the target.  It doesn’t need to know exactly where the plane is because the missiles themselves will determine that if they’re placed close enough for government work.  Maybe the battery needs to bring two or three missiles in from different directions all at once  so that no matter what the target does, at least one of the missiles can “see” it’s big, fat radar reflective belly or top.  Or, maybe these newfangled Russian missile radars are so bloody good that if they’re coming straight down at a stealth aircraft, they can see it as the fighter shaped hole in the radar reflection off the ground below it.  I don’t know.  What I can tell you is that the Russians know the answer because they know the math, and they’re pouring more money into the S-400/500 than into the SU-35.



#350 Loopycrank

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Posted Yesterday, 04:27 PM

 

It seems highly unlikely the Su-35 would be given a choice or any warning if an F-22 was in theater.

You should not underestimate it. N035 is VERY powerful radar, and it can be able to catch F-22 from some decent ranges, at least not from perfect front. Plus IRTS cound provide some close warning capability.

 

 

More of the RUSSIA STRONK!!!111 crap.

 

The USAF has stated that the F-22 has an RCS equivalent to a metal marble from the front.  What that means is (intentionally) ambiguous.  It's a debate for seasoned experts exactly how many zeroes go after the decimal point.

 

N035 has a detection range of 400km against a target of unspecified RCS, but detection isn't the same as tracking or track while scan, let alone weapons lock.  Engagement range for N035 is a mere 140km against a fighter-sized target.

 

"Fighter sized target" probably means something in the neighborhood of 10m^2 RCS in X-band.

 

Let's assume that the F-22 is merely as stealthy as Sukhoi claims the PAK-FA is; .1m^2.  That's a factor of 100 smaller RCS.

 

The relation between RCS and detection range is a fourth power relationship, so a factor of 100 reduction in RCS translates to a factor of 3.16 reduction in detection range.  So the SU-35 is down to 44km or so before it can shoot at a raptor from the front.  Assuming the raptor is flying straight at the flanker and not making things difficult, e.g. by going below the flanker's radar horizon and forcing it to use doppler filtering (which will knock of 20% or so off the range of the flanker's radar), or engaging its jammer (AESA radars double as jammers with the right software control).  That's well inside the maximum engagement envelope of the AIM-120C.

 

Let's assume that thirty-something years of experience and an order of magnitude better funding actually counts for something, and Lockheed Martin did better than merely matching the PAK-FA.  Let's assume that the F-22 has an RCS of .01m^2.  That's a factor of a thousand times smaller RCS than a typical fighter, which gives a detection range of 5.62 times smaller.  That means it's 71 kilometers before the Bars radar can even see the F-22, assuming that 400km is also vs. a fighter-sized target.  It's 24km before the SU-35 can guide a missile, which isn't just inside the envelope of an AIM-120, it's starting to get inside the envelope of an AIM-9X.

 

But ten centimeters is an awfully big marble.  What if the F-22 has a frontal X-band RCS of just a centimeter?  In that case, detection range is reduced by a nice, round factor of 10.  The SU-35 is going to have trouble locking up the F-22 outside of visual range if that's the case.

 

That is not by any reasonable definition "decent ranges."

 

 

Jaro You cannot overcome laws of physics... and radar equation is just that... a physics... there is no miraculous technology that will make stealth obsolete, all "stealth killer" technologies come with huge downsides and constrains people promoting them completely ignore...

 

 

From what I understand from Ben Rich's book, stealth works in two dimensions - to the front, sides or back.  It does not work up and it does not work down.   How do I know that?  Because Ben Rich says the surface has to be angled back 70 degrees from the emitter, and any plane’s topside or belly is a flat radar reflector.   The plane uses a SAM map to weave a path between radars, such that the defending batteries are never close by.  Directly below is dangerous because the belly of the plane allows a lock on – don’t ever fly over a SAM battery.

 

So what S-400 appears to do is use a low frequency radar to get a general location of the stealth aircraft (within an area of uncertainty of a few miles).  It then it fires one or more very expensive active radar homing missiles in ballistic trajectories to the area of the target.  It doesn’t need to know exactly where the plane is because the missiles themselves will determine that if they’re placed close enough for government work.  Maybe the battery needs to bring two or three missiles in from different directions all at once  so that no matter what the target does, at least one of the missiles can “see” it’s big, fat radar reflective belly or top.  Or, maybe these newfangled Russian missile radars are so bloody good that if they’re coming straight down at a stealth aircraft, they can see it as the fighter shaped hole in the radar reflection off the ground below it.  I don’t know.  What I can tell you is that the Russians know the answer because they know the math, and they’re pouring more money into the S-400/500 than into the SU-35.

 

 

I think you're greatly overestimating how much velocity missiles lose when they turn.

 

Also, planes can roll.


Edited by Loopycrank, Yesterday, 04:35 PM.


#351 GARGEAN

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Posted Yesterday, 05:31 PM

blah

Yeap. Instead of screaming about "russian bias" you can actually read what I wrote. Exactly about non-straightforward go and not about engaging, but only about warning of presence. And yeap, I truly love those hard bashings with numbers based on just stated "metal marble". Not even talking about from what exact axis(0-10 deg from const axis, 0-20 or just 0) or at what wavelenght.
All we know exactly is that N035 is 20Kw output X-band radar with huge scan envelope thanks to el+mech scan that can detect(not track) 3m^2 target at 350-400km head-on and 0.01m^2 from 80-90km.
But definitely F-22 would be unspottable because metal marble.

#352 Loopycrank

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Posted Today, 03:38 AM

 

blah

Yeap. Instead of screaming about "russian bias" you can actually read what I wrote. Exactly about non-straightforward go and not about engaging, but only about warning of presence. And yeap, I truly love those hard bashings with numbers based on just stated "metal marble". Not even talking about from what exact axis(0-10 deg from const axis, 0-20 or just 0) or at what wavelenght.
All we know exactly is that N035 is 20Kw output X-band radar with huge scan envelope thanks to el+mech scan that can detect(not track) 3m^2 target at 350-400km head-on and 0.01m^2 from 80-90km.
But definitely F-22 would be unspottable because metal marble.

 

 

I'm not sure what your argument is; could you try having more coherent thoughts?

 

We don't need to know the exact angle of radar engagement.  This image is the simulated RCS of an FB-23ish design that was created by Cal Poly engineers as part of an exercise:

 

xsCCmxo.png?1

B1ESHa0.png

 

Note that the RCS values are on a base 10 log scale.  Per the paper, the signal calibration is such that -12dB=.05m^2 RCS.  If you don't know what that means, consider learning math.  Note also they they stay quite low until the radar is perpendicular to the leading edge of the wing.

 

All stealth aircraft have a similar RCS "snowflake" shape.  In fact, this shape is part of why the name "black widow" was chosen for the YF-23.  Note that it also changes very little with aircraft attitude, at least within a realistic envelope of aircraft attitudes.



#353 lastdingo

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Posted Today, 04:20 AM

Keep in mind the RCS values - the correct ones, not the publicly discussed ones - are nominal values. They are bound to differ from plane to plane a little and they will differ from day today as well. Also, RCS differs between wavelengths.

 

I suppose a stealthy plane whose pilot is well informed about hostile sensor types and locations and is flying in a superbly maintained aircraft will be able to pull off what stealth proponents hope for. You won't consistently get such performance in a multi-week conflict with 2-3 sorties per day, of course.

 

There are about 186 F-22s, and one should not expect more than 170 of them deployable on short notice. This makes them scarce, and thus it's possible that missions over hostile ground would be very rare. After all, flying there risks unexpected radars to become active on the ground, ground-based infrared sensors picking the plane up even at 60,000 ft, AEW couldn't warn about threats approaching from outside the radar cone and so on. Defensive CAP missions would be much safer, and allow the F-22 to fight at conditions that suit it best. Ground-based radars may thus be not very relevant to F-22 operations.



#354 jaro

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Posted Today, 05:31 AM

and both are wide band actually.. F35 is better in this due to STEALTH coat paint which is designed to absorb quite wide range of frequencies.. F22 is supposed to get the same painting soon..



#355 Loopycrank

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Posted Today, 06:06 AM

Keep in mind the RCS values - the correct ones, not the publicly discussed ones - are nominal values. They are bound to differ from plane to plane a little and they will differ from day today as well. Also, RCS differs between wavelengths.

 

I suppose a stealthy plane whose pilot is well informed about hostile sensor types and locations and is flying in a superbly maintained aircraft will be able to pull off what stealth proponents hope for. You won't consistently get such performance in a multi-week conflict with 2-3 sorties per day, of course.

 

 

You're making some pretty dubious assumptions here.

 

1)  RCS is, with the current level of technology, more a function of shaping than of the RAM.  So yes, the RAM degrades from all sorts of things (although the current generation stuff is supposed to be much tougher), but the shape of the aircraft does not change.  The Vendetta above had its RCS calculated assuming the aircraft was entirely made of un-treated metal, and it still had a much better-managed frontal RCS than a conventional aircraft:

 

300px-Sigma_invader_RCS.png

 

2)  Any compromises to radar cross section can be monitored, and fairly easily.  There are a number of systems to check an aircraft's RCS before it's thrown up in the skies.  In fact, with ISAR signal processing, it's even possible to locate any problem hotspots on the airframe.  Addressing the same is often a rear-line facility job, but at the very least an aircraft with severely compromised RCS would not be sent into the fray unknowingly.  I have heard of these sorts of problems, and they are usually due to the aircraft suffering geometrical distortion, e.g. from bumping into something.  So severe reduction of stealth performance would only be likely in the event of physical damage to the airframe.

 

So your assertion that stealth performance would be degraded as a result of a protracted conflict is on shaky ground.



#356 Yama

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Posted Today, 06:23 AM

PAK-FA has DIRCM, and F-35 will bet getting it in a later block.


Few years ago they talked about 'upcoming requirement' for DIRCM for Block 5, but I haven't heard anything of it since that, and I have my doubts about fitting such a bulky system internally on F-35. They have talked about prospective podded self-defence laser, but that is long way out.

Both F22 and F35 utilize cooling system, where cold air is mixed with the exhaust. some of cool air is even used to cool down the plane surface in F35.. so these planes have also reduced IR signature to maximum..  any IR missile trying to lock on frontally, would face much smaller IR signature than it is designed against.. Chances improve from rear aspect, but what are the chances a 4gen would sneak on stealth plane from the rear...


I think the IR VLO efforts on fighters are pretty marginal. Even non-cooled IR sensors can easily detect a temperature differential on scale of human body warmth. Even LO fighter design has temperature differential dozens of times higher than that, and then they hit the afterburner...




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