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#3932409 - 03/31/14 07:37 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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And this leads us to SAMSIM unrealistic (what-if) scenario with Vega in Serbia :-)

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#3932593 - 03/31/14 04:54 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Alien_MasterMynd]  
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Originally Posted By: Alien_MasterMynd
And this leads us to SAMSIM unrealistic (what-if) scenario with Vega in Serbia :-)


Why not using this equation instead?

http://www.radartutorial.eu/01.basics/The%20Radar%20Range%20Equation.en.html

#3932692 - 03/31/14 07:06 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Alien_MasterMynd]  
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Is it unrealistic?

In a very, very basic sense, you can think of a stealth fighter/bomber as an aircraft that will be detected at about 1/10th the range that you would detect a 'normal fighter' at. If the Vega can pick up a basic fighter 3-6m^2 at 300km, then there's nothing strange about it picking up an F-117 at 30km.

If, however, the radar is also being jammed, then it may be operating on a lower gain, so that range shrinks even more.

Originally Posted By: Alien_MasterMynd
And this leads us to SAMSIM unrealistic (what-if) scenario with Vega in Serbia :-)


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#3932721 - 03/31/14 07:51 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: GrayGhost]  
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Originally Posted By: GrayGhost
Is it unrealistic?


It is unrealistic, because no SA-5B where available in Serbia....

And SA-5 (Dubna) could track a target with RCS ~ 0.08 m2 at 15 km altitude at 100 km distance...

Last edited by piston79; 03/31/14 07:54 PM.
#3932724 - 03/31/14 07:55 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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With a nominal 3m^2/300km, and 0.025m^2 I get a detection range of 90km (range and cross section both raised to power ^1/4).

(Nominal max range if ambiguity not an issue for B-52 class "barn door" is 720km).

With the 6m^2/300km baseline, I get 75km and 605km. There could well be additional factors not considered, but 1/10th seems massively optimistic for this factor at first blush (in favour of stealth).

#3932878 - 04/01/14 03:22 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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I tend to use -30dbsm for the F-117, but I have no idea if that's truly correct.


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#3932911 - 04/01/14 06:07 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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0.001m^2? for F117... 1/10th that of a 'typical bird'. Seems at odds with the actual observed shoot downs.

(*And* even with this revised value, I still get 34-40km detection range, for 300km at 6-3m^2 resp.)

#3932975 - 04/01/14 11:19 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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For the S-200VE Vega (SA-5B) RPC with 0.7deg, MHI mode (!!!) SAMSIM calculates with the following detection ranges if the target P=0:

F-117A real - 50km
F-117A simulated at Ashuluk - 100km
B-2A - 40km
MiG-21MF - 300km

PS: Please do not ask sources, its my educated guess only.
(Estimated target RCS is based on verbal accounts of those, who were operating real radars against real targets)

Last edited by Hpasp; 04/01/14 01:52 PM.

Hpasp
Free SAM Simulator, "Realistic to the Switch"

(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.)
http://sites.google.com/site/samsimulator1972/home

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

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#3933345 - 04/02/14 08:10 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: piston79]  
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Originally Posted By: piston79
Originally Posted By: Alien_MasterMynd
And this leads us to SAMSIM unrealistic (what-if) scenario with Vega in Serbia :-)


Why not using this equation instead?

http://www.radartutorial.eu/01.basics/The%20Radar%20Range%20Equation.en.html


Yes, the calculation is very simple. But trying it in SAMSIM is somewhat more exciting thumbsup

#3933346 - 04/02/14 08:10 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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Originally Posted By: Hpasp
For the S-200VE Vega (SA-5B) RPC with 0.7deg, MHI mode (!!!) SAMSIM calculates with the following detection ranges if the target P=0:

F-117A real - 50km
F-117A simulated at Ashuluk - 100km
B-2A - 40km
MiG-21MF - 300km

PS: Please do not ask sources, its my educated guess only.
(Estimated target RCS is based on verbal accounts of those, who were operating real radars against real targets)

Thanks thumbsup

#3933479 - 04/02/14 04:25 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Lieste]  
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Originally Posted By: Lieste
0.001m^2? for F117... 1/10th that of a 'typical bird'. Seems at odds with the actual observed shoot downs.

(*And* even with this revised value, I still get 34-40km detection range, for 300km at 6-3m^2 resp.)


The 0.001 square meter RCS value for the F-177 isn't probably that far as you might think.
I don't have concrete RCS values for the F-117 but I have read that the F-35 RCS is the same of a golf ball, so considering that the area of a golf ball is 9.3 square inches and that converted to square meters gives us a value of 0.006, which again isn't far off from the F-117 value of 0.001, specially considering that the F-35 is considered to be a little bit less stealthier than the F-117.

Besides as I previously said the RCS will in fact vary depending on the angle that the aircraft is facing the radar source. For example if a stealth aircraft such as the F-117 is heading towards the radar (frontal arc facing the radar) this same aircraft will be less detectable (or detectable at a shorter range) than if the aircraft would be flying in a perpendicular path relative to the radar.
Also, those RCS values that we have are average values or resuming it's the average of the frontal arc RCS, with side arc RCR, with rear arc RCS and so on. This means that the RCS from the frontal arc or any aircraft, specially stealth aircraft (since they are designed this way) is lower than the RCS values that we see in public sources (which again are average values).

Using the examples above, some of you came with the calculation that a SA-5 will detect a F-117 at 30km, others say 40km, others even say 100km but independently who's right, the value will be lower if the F-117 is flying towards the radar source (exposing its frontal arc).

Saying this, I would like to ask if SAM Simulator models diferent RCS for the same aircraft, depending on its angle towards the radar or not (RCS is the same for every angle)?

#3933489 - 04/02/14 04:51 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: ricnunes]  
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For the S-200VE Vega (SA-5B) RPC with 0.7deg, MHI mode (!!!) SAMSIM calculates with the following detection ranges if the target P=0

thumbsup



Last edited by Hpasp; 04/02/14 04:52 PM.

Hpasp
Free SAM Simulator, "Realistic to the Switch"

(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.)
http://sites.google.com/site/samsimulator1972/home

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

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#3933502 - 04/02/14 05:06 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: ricnunes]  
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Also one additional comment for the RCS debate...
... when you are reducing the RCS, through a certain level, the detection range will not change so much...

Neva SNR detection range:

10sqr m - 80km* (bigger fighter)
1sqr m - 80km* (smaller fighter)
0,1sqr m - 10 sqr dm - ~50km (football)
0,01sqr m - 1 sqr dm - ~25km (tennis ball)
0,001sqr m - 10 sqr cm - ~15km (golf ball)
0,0001sqr m - 1 sqr cm - ~10km (dice)
0,00001sqr m - 10 sqr mm - ~5km (carbine bullet)

*limited by maximum displayed range

... so there is no point reducing it further of a point.
This is why newer US planes were designed with bigger RCS, but better flight performance.

Last edited by Hpasp; 04/02/14 05:09 PM.

Hpasp
Free SAM Simulator, "Realistic to the Switch"

(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.)
http://sites.google.com/site/samsimulator1972/home

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

thumbsup
#3933552 - 04/02/14 05:53 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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Originally Posted By: Hpasp
Also one additional comment for the RCS debate...
... when you are reducing the RCS, through a certain level, the detection range will not change so much...

Neva SNR detection range:

10sqr m - 80km* (bigger fighter)
1sqr m - 80km* (smaller fighter)
0,1sqr m - 10 sqr dm - ~50km (football)
0,01sqr m - 1 sqr dm - ~25km (tennis ball)
0,001sqr m - 10 sqr cm - ~15km (golf ball)
0,0001sqr m - 1 sqr cm - ~10km (dice)
0,00001sqr m - 10 sqr mm - ~5km (carbine bullet)

*limited by maximum displayed range

... so there is no point reducing it further of a point.
This is why newer US planes were designed with bigger RCS, but better flight performance.


Yes, those values are IMO very believable indeed.

Some RCS reductions may not decrease the detection range by much which I understand because RCS versus detection curve is exponential and not arithmetic but nevertheless a reduction of detection range will still happen. That's why for example, the RCS in the F-35 was extremely reduced on its frontal arc (it's even said that the front arc RCS in the F-35 is lower than the frontal arc RCS in the F-117) but not so much on the other sides/arcs (which in the end means that for example the average RCS in the F-117 is lower than the F-35).

Anyway my question whether "SAM Simulator models different RCS for the same aircraft, depending on its angle towards the radar or not (RCS is the same for every angle)?" is only for personal curiosity.
I'm not suggesting that SAM simulator should model different RCS for the same aircraft depending on its angle facing the radar. I completely understand if a single RCS value is used for each aircraft, after all for a PC simulation purposes this should be more than enough (IMO).

#3933559 - 04/02/14 06:02 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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Did you got the meaning of P=0 in the Soviet parametric coordinate system?
(it includes my answer*...)
biggrin

*yes

Last edited by Hpasp; 04/02/14 06:11 PM.

Hpasp
Free SAM Simulator, "Realistic to the Switch"

(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.)
http://sites.google.com/site/samsimulator1972/home

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

thumbsup
#3933563 - 04/02/14 06:14 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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Sorry I missed it Hpasp scuseme

Thanks for the reply!

#3933760 - 04/03/14 05:04 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: ricnunes]  
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Originally Posted By: ricnunes
Sorry I missed it Hpasp scuseme

Thanks for the reply!


I am missing the point of the discussion - SAM performance against STEALTH in SAM Sim or in real word? It should not have a difference! wink

P.S. Here already have some calculations - about F-117 we got 0.0017 sqr. meters.

Here some more:

#3933803 - 04/03/14 09:41 AM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: piston79]  
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Originally Posted By: piston79
Originally Posted By: ricnunes
Sorry I missed it Hpasp scuseme

Thanks for the reply!


I am missing the point of the discussion - SAM performance against STEALTH in SAM Sim or in real word? It should not have a difference! wink


In a perfect world, yes Simulation and Real values would be equal. But in the real (and imperfect) world we know or should know that Simulations values are compromises between real values and "guessed" values (due to a number of factors/reasons) which means that often the values we have in simulations are not or cannot be exactly the real ones.



Originally Posted By: piston79

P.S. Here already have some calculations - about F-117 we got 0.0017 sqr. meters.



I would say that your value makes perfect sense. If we round that value we have for the F-117 something like 0.002 which is lower than the F-35 0.006 RCS value, which concurs with "official" sources. The B-2 RCS should be lower than the F-117 but I don't have an idea what is its RCS.

#3933993 - 04/03/14 05:39 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: Hpasp]  
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#3933999 - 04/03/14 05:52 PM Re: B-2 over Belgrade....an extraordinary technical achievement [Re: piston79]  
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Of all the remarkable achievements
of the B-2 at war, four stood out:
opening the air campaign, flying
alone, destroying an SA-3, and
taking down the Novi Sad bridge.

Last edited by piston79; 04/03/14 06:10 PM.
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