Forum: F-22A Raptor

toan wrote:

3. As for the declaration of IRBIS-E's detection capability:
http://aeroreview.ru/?/pages/ako/ako_20 ... 01_020.htm
http://www.chile.mid.ru/misc/fidae2006_e_03.html
http://forums.bharat-rakshak.com/viewto ... &start=160

RLSU Irbis-E can locate and simultaneously track up to 30 aerial targets with the retention of the continuity of the survey of space (track while scan), ensure the simultaneous fire of two targets with two rockets with semi-active RGS and up to eight targets by eight rockets with active RGS, in such cases to four targets at the distance of more than 300 km. In the mode 'air-surface' the complex ensures the mapping of land and sea surfaces and the detection of ground targets in the modes of survey with real beam (low resolution) with the Doppler sharpening (medium resolution) and SAR mode (modes of high and superhigh resolution). Range of detection of aerial targets RCS 3 sq m in the head-on courses in RLSU Irbis-E comprises not less than 350-400 km, while in the overtaking courses - not less than 150 km (with the height of target 10 km and more). To detect 'stealthy' targets RCS 0.01sq m station can at the distances to 90 km. Resolution during the identification of dense multiple target (at a distance of 50 km) it comprises: on the distance - 50-100 m, on the velocity - 5 m/s and on the angular coordinates - 2,5～.

Being the logical development Bars, RLSU Irbis, thus, has considerably higher characteristics: the extended (more than doubled) zone the working of frequencies, the increased from 70 to 120 deg zone of detection and accompaniment of aerial targets along the azimuth, the considerably increased range, the improved jamming invulnerability, etc through these indices Irbis is located on the level of the most up-to-date foreign developments in this region, exceeding the majority of American and West European RLS with the passive and the active phased arrays and practically without being inferior to the most perfect system of this class - RLS AN/APG-77 of American fighters F-22.

Over-exaggerated advertisements?? perhaps, Nothing more than BS?? maybe. However, All of these stuffs that I mentioned above were from the manufacturers' and USAF / RAF's declaration, not from my personal imagination.

The declaration of Manufacturers and Air-Force:

USAF:
"With the help of AESA radar and NG data fusion / link technology, our F-22A and F-35 shall be a invincible and numerous AWACS fleet with stealthy capability and detection range of E-2C/E-3C class at least (or even better ~ I don't know if E-2C, or even E-3C nowadays can detect the target of RCS = 1 m2 class 200 km away. However, APG-77 can "track" this kind of target at the range more than 200 km away). Therefore, there's no need to develop and buy E-10 now."

Russian fighter's radar manufacturer:
"Our newest phase array radar (IRBIS-E) will have 20 Kw class maximal output (4 times of APG-71) and the similar detecting / tracking range performance as APG-77."

RAF / EADS / BAES:
"The CAPTOR-M now is able to track MIG-29 (RCS = 5m2) at the range more than 161 ~ 185 km away. It is very impressive for a traditional fighter's radar, however it is relatively shabby when comparing with the NG AESA radars such as APG-77, APG-81, and IRBIS-E. However, after incorporating AESA technology into CAPTOR formally in 2014 (CAPTOR-E), we shall be able to chase them up..........."

I’d be extremely skeptical about these manufacture claims. Sure one should take the AvLeak numbers and US/NATO/Western Allies claims with a grain of salt too, but the claims about the IBRIS-E don’t gel with physics. Referencing the Fuhs’ equation for area search – which is usually good for a quick back of the envelope calculation – one can see that the 3sqm at 400 km shouldn’t be able to detect a 0.01sqm target at 90km. In fact according to the Fuhs equation, it should normally be good for around 23km if the baseline 3sqm target can be detected at 400km. Now if that was a misquote or a typo and was actually a 0.1sqm target, that should be detectable at around 73km.

I don’t doubt that there could be advanced waveforms or search algorithms such as ILST that might boost detection range, but I highly doubt they could get more than three times the performance that the Fuhs equation suggest should be possible for a LO target (0.01sqm). There is one other possibility. Perhaps when they refer to “similar APG-77 performance” they are in fact referring to when the radar is running at it’s max power- i.e. not operating in it’s various LPI modes. In that case – according to AvLeak – it should be good for about 290km for a 1sqm target, which would put its range against a 0.1sqm target at around 92km. That’s a bit more realistic.

That being said I’m skeptical that the Russians would be able to essentially leapfrog everyone is electronic hardware especially since that has not been an area that they’ve traditionally been strong in (such as aerodynamics). In the past the Russians have been known to embellish a bit and this seems like this might be happening here.

Regards,
Brad

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BDF wrote:

In that case – according to AvLeak – it should be good for about 290km for a 1sqm target, which would put its range against a 0.1sqm target at around 92km. That’s a bit more realistic.

Stealth aircraft typically have an RCS far less than 0.1m^2

sferrin wrote:

Stealth aircraft typically have an RCS far less than 0.1m^2

Yes I know, the Raptor has been reported to be in the -40dbsm range for instance. The Russians have varied their descriptions of what constitutes a "stealth" aircraft (to them obviously). I was however merely offering possibilities of where those numbers came from. In the end I'm still skeptical of the 90km figure. Time will tell.

Brad

Lets not forget antenna output means nothing for filtering it from the background noise. A plane needs a strong signal processor. All those ranges, even calculated using equations could be still way off if the signal processor cant make it out from the background noise. Specialy in look down.

Also, take in consideration the presence of standoff jamming. That seriously degrades radar performance.

Pilotasso wrote:

Lets not forget antenna output means nothing for filtering it from the background noise. A plane needs a strong signal processor. All those ranges, even calculated using equations could be still way off if the signal processor cant make it out from the background noise. Specialy in look down.

This is very true, stealthy planes are actually detected at the extreme ranges of all radars, but the signal that is them is filtered out as nothing more than noise. That is what most people don't understand, there's always noise from the surroundings and the plane itself. The more electronics that go on planes, the more electronics on the planes, the stronger the electric and magnetic fields around the plane are. That means they have to filter that and these things are not necessarily predictable, thus Gaussian noise. At any rate, more power = more return = not going to be filtered = longer detection range. And all this from using an oscilloscope a few times and reading this forum.

A very random aside, Also, the planet is going to go through a pole flip sooner or later which means a lot more background radiation that has to be filtered.

Forum: F-22A Raptor

The Truth about the Raptor