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#4319869 - 12/14/16 08:15 PM Re: S-300PS/PMU (SA-10B Grumble) ***** [Re: Hpasp]  
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Originally Posted By: Hpasp
And what can you tell us about the RCS of the B-2A?


Well the link above says that the F-35 is stealthier (lower RCS) compared to the B-2 which means that the B-2 RCS could be higher than 0.001 square meters.

However there's always the angle of the aircraft towards the radar source factor but again I take these RCS values to be average values (taking into account several angles/aspects of the aircraft).
What I mean with this, is that it's almost certain the F-35 is stealthier from the frontal aspect compared to the B-2 (I believe this is a given fact) but I wouldn't rule out the possibility that the B-2 could be stealthier than the F-35 from the side or rear aspect even comparing with the F-35 (but this I don't know - it's only speculation from my part). This is known to be the case when comparing both the F-35 and the F-22 in terms of RCS.

The link that I gave you earlier contains the closest to an official information that I could gather from the B-2 RCS. So I don't know what's the RCS of the B-2 for sure. I've also seen RCS values on the web for the B-2 being lower than those of the F-35 (-30dBsm for the F-35 while -40dBsm for the B-2) but in case if these values are actually correct this could be the case that these RCS values are average values between several aspects of each aircraft (towards the radar source) instead of a single aspect (like frontal for example) that I was talking about.


Originally Posted By: Hpasp

The F-117A was already measured to be -28dBsm in a competitive environment.
biggrin


Yup.
What's funny is that there are many people that for some reason trend to think that only radar and/or air defence systems evolve over time but for some odd reason that Stealth Technology stay static and the same "forever" (like Stealth Technology for some odd reason couldn't evolve).

Regarding the RCS (in this case about the F-35 again versus air defence systems) I noticed that piston79 beat me in posting this:

http://www.businessinsider.com/f-35-us-air-force-too-stealthy-2016-8


Originally Posted By: Hpasp

Meanwhile...


Oh Donald Trump, Donald Trump... What can I say?? Is it worth mentioning a guy that probably doesn't know the difference between a wing and a landing gear?? biggrin

Last edited by ricnunes; 12/15/16 12:58 PM.
Inline advert (2nd and 3rd post)

#4320317 - 12/16/16 06:43 AM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Thank you for the sources.

The variance of RCS depending on design goals can be significant.



The variance of RCS depending on radar azimuth is much more significant in case of stealth, than in ordinary Alu jets, and RCS spikes are generally accepted in the design.



Radar wavelength also plays in the radar received signal power, and on long wavelengths the RCS can be 5~10dBm higher.
In case of active low frequency radar signal suppression (cancellation) is used, this effect can be small.



Flight altitude in case of B-2A, resulted total impunity during OAF, while the Yugoslavs had only low altitude Neva and KUB systems deployed.
Flying at 40~50kft even with the same RCS as the F-117A had, resulted slant ranges simply outside of Neva SNR capabilities.
No accident that from the 15th night of the war, B-2As were allowed to fly without package support, as NATO become sure that Serbians has no operating S-75M Volhov / SA-75M Dvina systems.
S-75M Volhovs were scrapped by the Dayton peace accord, SA-75M Dvina were removed from service years earlier.



Source of the charts: ADA464771 B-2 Systems Engineering Case Study
www.dtic.mil/get-tr-doc/pdf?AD=ADA464771

Further arguing on system capabilities that are under development (no public sources but just heavy marketing) or offered for export in the (far-far) future is always thin ice, I would rather avoid.

I hope, that most of you recognized that the S-400 system detailed here...
http://SimHQ.com/forum/ubbthreads.php/topics/4319049/Re:_S-300PS/PMU_(SA-10B_Grumbl#Post4319049
... is an export version with downgraded capabilities, where one aspect was already mentioned earlier.

DJT might be uneducated in military topics, but he is the elected commander-in-chief.

Last edited by Hpasp; 12/16/16 07:38 PM.

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#4320337 - 12/16/16 11:28 AM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Quote:
The U.S. Air Force, in it’s effort to get money to build more F-22s, has revealed just how “stealthy” the F-22 is. It’s RCS (Radar Cross Section) is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better than the B-2 bomber, which, in turn, was twice as good as that on the even older F-117.


This quote does not fit with the real life measurement of the Yugoslav Air Defense.

F-117A radar detection range with P-18: 28km (upper beam can detect a 1sqrm RCS target from 150km)
F-117A measured RCS: 0,001sqrm, -30dBsm, similar to a 3,6cm diameter metal ball

It seems that the F-35A advertized RCS is inferior to the measured RCS of the F-117A.

F-35 advertized RCS: 0,0014sqrm, -29dBsm, similar to a 4,3cm diameter metal ball

I asked the B-2 advertized RCS, to point at this contradiction.



Last edited by Hpasp; 12/16/16 02:09 PM.

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#4320445 - 12/16/16 05:38 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Thanks for the charts Hpasp, are they original declassified Northrop documents?

They show that the difference of RCS was expected to be about 2.5 times when comparing a x-band fire control radar and a VHF search radar such as the P-18.

For the S-400 it would mean that if used with the Nebo-M its detection range is against a ~ 2.5 times larger RCS target than the nominal detection range against those x-band golf ball and marble RCS statements of the US DoD. The 0.0014m² sphere becomes a 0.0042m² sphere. I dont have the radar equation at hand but a 500km class system such as the Nebo-M should have a useful range against a 0.0042m² (virtual RCS in VHF band) target. It should be added that this value should be even higher for VHF band radars as RAM and RAS is optimized and effetive for x-band and similar band radars much less effective in VHF band.

The question for a successful engagement is at which range the S-300/400 tracking radar will pick up the identified target. Here the brute force of a large aperture PESA able to create a concentrated pencil beam should be the key to put enough energy on the target. It should be possible that the VHF detection range would't be much higher than the tracking range again low-RSC targets.

*Edited for some corrections

Last edited by Patarames; 12/16/16 07:06 PM.
#4320505 - 12/16/16 08:12 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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NEBO-ME has 510km detection range against a 1sqrm target.

F-22 with "marble" RCS could be detected from ~50km.
F-35 with "golf ball" RCS could be detected from ~100km.







In service.

Last edited by Hpasp; 12/17/16 08:04 AM.

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#4320507 - 12/16/16 08:23 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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I need to correct myself again.

Based on the Tacit Blue chart the delta between VHF and X-Band is not 2.5 times but 2.5 DBSM. If we take the golf ball value of 0.0014m² which translates to 28.5 DBSM at 2.5 less DBSM, 26 DBSM we would have a 0.0025m² target in VHF band. Less than half of my false number in the previous post.

#4320663 - 12/17/16 08:59 AM Re: S-300PS/PMU (SA-10B Grumble) [Re: Patarames]  
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Originally Posted By: Patarames
I need to correct myself again.

Based on the Tacit Blue chart the delta between VHF and X-Band is not 2.5 times but 2.5 DBSM. If we take the golf ball value of 0.0014m² which translates to 28.5 DBSM at 2.5 less DBSM, 26 DBSM we would have a 0.0025m² target in VHF band. Less than half of my false number in the previous post.


No scale on DBSM, how calculated that...?

#4320677 - 12/17/16 12:22 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Originally Posted By: Hpasp
Quote:
The U.S. Air Force, in it’s effort to get money to build more F-22s, has revealed just how “stealthy” the F-22 is. It’s RCS (Radar Cross Section) is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better than the B-2 bomber, which, in turn, was twice as good as that on the even older F-117.


This quote does not fit with the real life measurement of the Yugoslav Air Defense.

F-117A radar detection range with P-18: 28km (upper beam can detect a 1sqrm RCS target from 150km)
F-117A measured RCS: 0,001sqrm, -30dBsm, similar to a 3,6cm diameter metal ball

It seems that the F-35A advertized RCS is inferior to the measured RCS of the F-117A.

F-35 advertized RCS: 0,0014sqrm, -29dBsm, similar to a 4,3cm diameter metal ball

I asked the B-2 advertized RCS, to point at this contradiction.




Actually the slight contradiction that we may be observing may not be a matter of "contradiction" but a matter of "rounding" or "value rounding" instead.

I admit that the following calculation that I'm going to post here is a bit hasty (so there's the possibility of error) but if we consider the RCS of the F-117A in square meters to be for example 0.00149 and converting this to dBsm we would have something around -28dBsm, right?

While at the same time a RCS of 0.00143 square meters or smaller (F-35 RCS) would put it more closely to the -29dBsm value.
Note that the "golf ball" size is a "reference size" (and likely not an "exact size") which is likely aimed for the general population (which doesn't have much knowledge about these subjects) so it's also likely that the F-35 RCS size could actually be a bit smaller than a golf ball itself.

So and resuming, if the real F-117 RCS would for example be 0.00149 this would be -28dBsm which by the way is the value that you gave earlier about the F-117A which IMO sounds about right.
But if you use the rounded value of 0.00149 to three (3) decimal places we would have 0.001, which means that "in theory" using both 0.00149 or 0.001 square meter RCS values for the F-117A would be somehow "correct".
However if using both values as absolute values to calculate the dBsm we would get different values, -28dBsm for 0.00149 and -30dBsm for 0.001.

This same rule/issue would also apply for the F-35 RCS where 0.00143 rounded up would also be 0.001 (like the rounded F-117A RCS value) but and nevertheless the F-35 would still be stealthier and with a dBsm value closer to -30dBsm when compared to the F-117A, or resuming the value of -29dBsm which you posted which again IMO it sounds about right as well.

Also note that the dBsm values are also "rounded values".


Oh, and thanks for charts and information Hpasp.

#4320679 - 12/17/16 12:35 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: piston79]  
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Originally Posted By: piston79
Originally Posted By: Patarames
I need to correct myself again.

Based on the Tacit Blue chart the delta between VHF and X-Band is not 2.5 times but 2.5 DBSM. If we take the golf ball value of 0.0014m² which translates to 28.5 DBSM at 2.5 less DBSM, 26 DBSM we would have a 0.0025m² target in VHF band. Less than half of my false number in the previous post.


No scale on DBSM, how calculated that...?



I found this formula on the web and this is what I use to calculate the dBsm values:

dBsm = 10 x log10(RCS/1m^2)


Basically all you need is to replace "RCS" with the value in square meters which you want to convert into dBsm.

Also "1m^2" means "1 square meter" and "log10" means "logarithm (base 10)".

#4320718 - 12/17/16 03:42 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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My guess would be:
biggrin



Last edited by Hpasp; 12/17/16 04:04 PM.

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https://sites.google.com/view/nuclear-weapons-in-hungary/

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#4320801 - 12/17/16 09:38 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: piston79]  
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Well I just took the most conservative approach, the axis is labelled with DBSM so one unit is assumed to be one DBSM.

The graphs are so important because its one of the rare cases where a US document quantifies the RCS difference of different bands. Hence we can use exclusively US sources to quantify the effect of X-band compared to VHF-band. As you know Russia, China and recently Iran seem to be convinced that their VHF-band radars are effective against US low-RCS systems.

But as you said, we are not sure what one of those units really mean, Hpasp's guess could also be right.

#4320802 - 12/17/16 09:44 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Do not forget the important note on the chart.

NO LOW FREQUENCY SUPRESSION

With low frequency radar signal supression, the effect of VHF +10dBsm might be negated.

Note that the B-2A is equipped with a Northrop Grumman AN/ZSR-63 defensive avionics suite, and its function was never described in public.

Last edited by Hpasp; 12/17/16 09:54 PM.

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Book from the author - Soviet Nuclear Weapons in Hungary 1961-1991
https://sites.google.com/view/nuclear-weapons-in-hungary/

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#4320894 - 12/18/16 07:56 AM Re: S-300PS/PMU (SA-10B Grumble) [Re: ricnunes]  
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Ok, lets try to summarize our discussion so far...

Approximate RCS averages;
F-117 and the F-35; -30dBsm, 4cm diameter metal golf ball
B-2; -35dBsm, 2cm diameter metal ball
F-22; -40dBsm, 1cm diameter metal marble

...but in this case, the corrected quote would be;

The U.S. Air Force, in it’s effort to get money to build more F-22s, has revealed just how “stealthy” the F-22 is. It’s RCS (Radar Cross Section) is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better on the frontal aspect than the B-2 bomber F-117.
B-2 bomber which, in turn, was twice as good as the even older F-117.


biggrin

Last edited by Hpasp; 12/18/16 10:20 AM.

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(U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.)
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Book from the author - Soviet Nuclear Weapons in Hungary 1961-1991
https://sites.google.com/view/nuclear-weapons-in-hungary/

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#4320949 - 12/18/16 02:30 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Originally Posted By: Hpasp
Ok, lets try to summarize our discussion so far...

Approximate RCS averages;
F-117 and the F-35; -30dBsm, 4cm diameter metal golf ball
B-2; -35dBsm, 2cm diameter metal ball
F-22; -40dBsm, 1cm diameter metal marble


Yes, those values look quite believable to me and makes sense specially when compared with what's publically known.



Originally Posted By: Hpasp

...but in this case, the corrected quote would be;

The U.S. Air Force, in it’s effort to get money to build more F-22s, has revealed just how “stealthy” the F-22 is. It’s RCS (Radar Cross Section) is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better on the frontal aspect than the B-2 bomber F-117.
B-2 bomber which, in turn, was twice as good as the even older F-117.


biggrin


In general I agree with the above except for the first Strikethrough text. In my opinion is should be:

Quote:

The U.S. Air Force, in it’s effort to get money to build more F-22s, has revealed just how “stealthy” the F-22 is. It’s RCS (Radar Cross Section) is the equivalent, for a radar, to a metal marble. The less stealthy (and much cheaper) F-35, is equal to a metal golf ball. The F-35 stealthiness is a bit better on the frontal aspect than the B-2 bomber and the F-117.
B-2 bomber which, in turn, was twice as good as the even older F-117.



Like I previously said, the F-35 is also stealthier than the F-22 on the frontal aspect (for example this was somehow confirmed by USAF Gen. Mike Hostage) and if the F-35 is indeed stealthier than the F-22 on the frontal aspect than it should also be stealthier than the B-2 on the frontal aspect as well.
Actually this shouldn't be hard to achieve or to conceive.

First, the B-2 airframe design which is a flying wing which is a design that was found to be "stealth" by accident.
So it should be no wonder that dedicated (and more modern) aircraft stealth designs such as the F-22 and the F-35 could be stealthier than the B-2 specially on some angles like the frontal aspect.

Secondly and for example lets use the following guessed values:

B-2 frontal aspect RCS --> 0.0002 square meters
B-2 side aspect RCS --> 0.0004 square meters
B-2 rear aspect RCS --> 0.0003 square meters
In this case the Average RCS which is what we simply and usually know as RCS for the B-2 would be 0.0003 square meters (your B-2 RCS prediction).

Now for the F-35:
F-35 frontal aspect RCS --> 0.0001 square meters
F-35 side aspect RCS --> 0.002 square meters
F-35 rear aspect RCS --> 0.002 square meters
In this case the Average RCS which is what we simply and usually know as RCS for the F-35 would be around and close to 0.0014 square meters (F-35 RCS based on official information).


Please note that the values and calculations above are once again guessed values and simplistic calculations (a single average calculation between the 3 main aspects of an aircraft) but the purpose of this is to show that's it's clearly possible for an aircraft (F-35) to have a smaller RCS in the frontal aspect compared to another (B-2) but at the same time this same aircraft (F-35) to have an average RCS (or simply RCS) higher than the other aircraft (B-2).

#4320957 - 12/18/16 02:49 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Originally Posted By: Hpasp
Do not forget the important note on the chart.

NO LOW FREQUENCY SUPRESSION

With low frequency radar signal supression, the effect of VHF +10dBsm might be negated.

Note that the B-2A is equipped with a Northrop Grumman AN/ZSR-63 defensive avionics suite, and its function was never described in public.



Indeed and also notice that applies the same (actually even more effectively) to the F-35.

The F-35 defensive suite (such as the AN/ASQ-239) working together with the AESA radar (AN/APG-81) gives the F-35 a standoff jamming capability similar to the dedicated airborne jamming platforms such as the EA-18 Growler.
The F-35 defensive suite can also geo-locate radar sources.

Here:

http://www.baesystems.com/en-us/product/an-asq-239-f-35-ew-countermeasure-system

http://www.baesystems.com/en-us/download-en-us/20160718215911/1434583878736.pdf

https://www.f35.com/about/capabilities/electronicwarfare

#4321028 - 12/18/16 07:00 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Guys, those sneaky russians hacket that "SteaLTH":







#4321193 - 12/19/16 07:30 AM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Originally Posted By: Hpasp
My guess would be:
biggrin




This interpretation is closer to what Russians claim than my 1 DBSM per unit guess.

The very stealthy tacit blue would then have -35 DBSM at X-band and ~-13 DBSM at VHF band (delta of 22 DBSM) in other words, 0,0003m² vs 0,05m² RCS.

I wonder if this ~+22 DBSM VHF-band effect of this interpretation of the US document scale would proportionally apply to a -30DBSM F-35 class target, bringing it down to -8 DBSM or 0,16m².


I would also like to know at what range the Nebo-M could detect a 0,05 VHF-band tacit blue if its detection range against a 1m² target is 510km.

Whats more: The 92N6E X-band engagement radar of the S-400 has a range of 185km against a 0,4m² target. At no point its able to illuminate a target at 380km which is the claimed max. range of the S-400. So either the new long range 40N6 missile of the S-400 is equipped with a ARH seeker or they use some sort of trick to do it. It should be possible that the 92N6E would just illuminate the space in which the search radar have spotted something and guide the missile via data link towards it. Then in terminal phase the 40N6 would at one (late) point pick up the reflections and switch from data-link/command guidance to SARH, while the 92N6E radar is still out of range and cant track the target.

I think jamming to further reduce the detection range of enemy radars is a last ditch measure for stealth aircraft, used only if their location is compromised and emitter silence can be brocken. In a modern IADS environment and emitting jamming could lead to detection by passive systems or enable a ordinary S-300 missile to switch to HOJ for engagement.

#4321251 - 12/19/16 12:49 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Patarames]  
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Originally Posted By: Patarames
The very stealthy tacit blue would then have -35 DBSM at X-band and ~-13 DBSM at VHF band (delta of 22 DBSM) in other words, 0,0003m² vs 0,05m² RCS.

I wonder if this ~+22 DBSM VHF-band effect of this interpretation of the US document scale would proportionally apply to a -30DBSM F-35 class target, bringing it down to -8 DBSM or 0,16m².


More than 20 years have passed since Tacit Blue's first flight (1982) and the F-35 first flight (2006) so it's safe to assume that Stealth technology evolved a LOT since then (early 1980's).

In the end, while VHF and UHF radars in theory emits more powerful radio waves than for example X-Band radars granting them a slight improvement on detection range against stealth aircraft they still emit radio waves which can be deflected and/or absorbed (like the radio waves of a X-band radar).

What I mean is that I doubt that the F-35 RCS (the most modern stealth aircraft in the world) against a Nebo-M radar would be in the order of 0.16m² as you claim.


Originally Posted By: Patarames

I think jamming to further reduce the detection range of enemy radars is a last ditch measure for stealth aircraft, used only if their location is compromised and emitter silence can be brocken. In a modern IADS environment and emitting jamming could lead to detection by passive systems or enable a ordinary S-300 missile to switch to HOJ for engagement.


I believe that here you're confusing self-defence jamming such as is provided with pods/jammers like the ALQ-184 with dedicated Electronic Warfare Jamming that aircraft like the EA-18G Growler and of course the F-35 can do.

A traditional self-defence jamming that is found in many/most modern combat aircraft basically create a "noise cloud" around the aircraft which means that while it will be much harder to lock an aircraft while using its own self-defence jammer it will be easier to detect this same aircraft or more precisely to detect the "noise cloud" its jammer created.
This is what you described.

However, the F-35 as well as dedicated EW aircraft (like the EA-18G) can directly jam the radar source, so what you have in this case is basically a beam of noise directly pointed towards the radar source which will directly degrade the ability of this radar to detect anything at longer distances. Resuming this kind of jamming won't or shouldn't appear on the radar scope since this kind of jamming is directly degrading the radar detection ability.

#4321325 - 12/19/16 03:02 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Patarames]  
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Hpasp Offline
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Hpasp  Offline
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Originally Posted By: Patarames
This interpretation is closer to what Russians claim than my 1 DBSM per unit guess.
The very stealthy tacit blue would then have -35 DBSM at X-band and ~-13 DBSM at VHF band (delta of 22 DBSM) in other words, 0,0003m² vs 0,05m² RCS.

I wonder if this ~+22 DBSM VHF-band effect of this interpretation of the US document scale would proportionally apply to a -30DBSM F-35 class target, bringing it down to -8 DBSM or 0,16m².


On this one, I would tend to agree with ricnunes.
Stealth technology is improving over the time.
Tacit Blue +20dBsm VHF/X-band
B-2 +10dBsm VHF/X-band (without active suppression), with active suppression it might be +0dBsm
F-35 is much newer, so my guess would be +0dBsm (without active suppression)

Originally Posted By: Patarames
Whats more: The 92N6E X-band engagement radar of the S-400 has a range of 185km against a 0,4m² target. At no point its able to illuminate a target at 380km which is the claimed max. range of the S-400. So either the new long range 40N6 missile of the S-400 is equipped with a ARH seeker or they use some sort of trick to do it. It should be possible that the 92N6E would just illuminate the space in which the search radar have spotted something and guide the missile via data link towards it. Then in terminal phase the 40N6 would at one (late) point pick up the reflections and switch from data-link/command guidance to SARH, while the 92N6E radar is still out of range and cant track the target.


Idea is that Nebo-M detects the F-35 at 100km, and the S-400 battery engages it with the active guidance 9M96D missile (120km range), where the S-400 MFR just sends MCG based on the Nebo-M measurements.

Probably it is by no accident, that the SDB range is currently extended...


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#4321377 - 12/19/16 04:12 PM Re: S-300PS/PMU (SA-10B Grumble) [Re: Hpasp]  
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Patarames Offline
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Patarames  Offline
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@ricnunes

I think after the experiences of Northrop with the XST program by the time of Tacit blue they had mastered their methods for geometrical stealth, especially because the Tacit blue traded most of its aerodynamics for stealth and was a tech demonstrator. We can be quite confident that the changes until today were rather small as the law of physics stay the same, today a Tacit blue would probably just have better flying characteristics. If overall dimensions would significantly grow to B2 size, we could expect a great enhancement of geometric stealth performance in VHF band. The threat situation back then was also not much different with huge numbers of metric P-18/12 available to the Soviets, so the Tacit blue design was optimized for VHF band stealth performance.
The changes should be foundin RAM and RAS and this mainly in x-band where the wavelengths are within the size of the RAM layers and RAS. In metric wave the tacit blue is a good RCS representer and in this case, after 35 years we are lucky to have declassified documents available, we might lack the scale but Hpasp's interpretation makes much sense at this point.

You doubt my value of 0,16m² for the F-35, understandable because we lack the scale for those declassified US origin charts, fair enough. Hpasp once stated that he believes that the difference of X-band to VHF is in the order of 10 DBSM. I extrapolated 22 DBSM with his scale interpretation (which sounds credible) of this declassified US chart:


If we would make the simplification of proportional decreasing the 22 DBSM X-band/VHF delta effect of the tacit blue from the 30 DBSM of the F-35 we would get that 0,16m² RCS as result, all assuming that our scale interpretation and the simplification of proportional DBSM decrease are right.
If this interpretation based on this US documents would be right, a Nebo-M would detect a 0,16m² RCS (in VHF band) F-35 at a distance of 320km.

As for jamming
I'm aware of dedicated jamming by systems such as the Growler but I question it in this debate where systems such as the S-300 and -400 could target those aircrafts at extended ranges if used in HOJ mode.
But this topic lead me to research a little on VHF band radars performance in jamming environment. I came across this website of a Belarus upgrade program for the P-18 with quite much information and RCS-range values.

http://www.kbradar.by/en/products/radiol...ooruzheniya/99/

I found the discrimination of RCS-range for the P-18 particularity interesting, the value for a F-14 is 175km. Assuming that they used a RCS value of ~8m² and that the Serbian SA-3 site detected the F-117 at ~28km, a calculated a RCS of 0,005m² for the F-117 in VHF band. Also interesting is the performance under heavy dedicated jamming at 500km distance. Giving the huge degradation for the original analogue system I think we can assume that the range performance of the P-18 was also degraded to some extend. Hence that engagement which suggests a 10 DBSM difference for X-band to VHF-band could be the result of jamming and the true difference could be in the order of 20 DBSM interpreted and extrapolated from those declassified Tacit blue documents.

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