F-16.net

This is a table made by Stealthflanker (very knowledgeable guy) to predict radar ranges based on inputted variables such as pulse integration, scan sectors, antenna weighting scheme...etc.
http://www.mediafire.com/file/7wrkyslc1 ... Trial.xlsx
https://forum.keypublishing.com/showthr ... calculator

If that version is too complex for you, you can try this simplified table where many of the variables are pre calculated and more user friendly.
http://www.mediafire.com/file/7wrkyslc1 ... Trial.xlsx
For filling guide for PRF and pulse width you can check the following table:



i took the initiative and try estimate APG-81 range with some assumed variables:
T/R modules: 1626
Peak power per module: 10W
Operational wavelength: 2.5 cm
Aperture weighting: Cos^4
Radar PRF: 10 Khz, Pulse width: 20 micro sec => Duty cycle: 20 %
Scan time frame: 9 seconds for full field of regard.
Scan field of regard: 120° azimuth, 10° elevation (with the same scan time frame, wider field of regard will result in shorter dwell time => shorter range)


=> Against target with RCS = 1m2
Maximum detection range with 50% probably of detection = 260 km
Maximum detection range with 90% probably of detection = 162 km

Slightly different assumptions for APG-81:
T/R modules: 1626
Peak power per module: 10W
Operational wavelength: 3 cm
Aperture weighting: Taylor40D
Radar PRF: 10 Khz, Pulse width: 20 micro sec => Duty cycle: 20 %
Scan time frame: 9 seconds for full field of regard.
Scan field of regard: 20° azimuth, 10° elevation (Cued search => longer dwell time => longer range)

=> Against target with RCS = 3m2
Maximum detection range with 50% probably of detection = 391 km
Maximum detection range with 90% probably of detection = 242 km

I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.

Try the calculations using 16w modules.

sprstdlyscottsmn wrote:I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.

Yes, that's the result I got from calculating using similar formulas, variables and constants. Basically all PESA and MSA radars have to combat about 6 dB higher losses in transmit and receive paths together and thus smaller and less powerful AESA can have equal or superior range performance. This is in situation where there is no interference (like EW) or clutter. When those are present, AESA will be much better due to many factors.

Nice to see someone make such a easy to use Excel calculator for AESA radar range calculations. I'm definitely going to use this from now on!

sprstdlyscottsmn wrote:I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.

The first one is volume search
The second is cued search, so the detection range get much longer just like hornetfinn said.

wrightwing wrote:Try the calculations using 16w modules.

I don't know the exact peak power of APG-81 modules, so i play on the safe side and choose a small value.

I take it this assumes a clean sky (no competing RF creating interference or EW)?

playloud wrote:I take it this assumes a clean sky (no competing RF creating interference or EW)?

Yes, no jamming or clutter.

Is there one of these input variables that could be used to simulate that? What types of jamming even effect an AESA?

sprstdlyscottsmn wrote:Is there one of these input variables that could be used to simulate that? What types of jamming even effect an AESA?

No, there isn't any input variable for that, although that might be simulated to some degree by adding jamming power to radar loss budget. That would simulate very wideband noise jamming effects. I don't think there is a way to simulate effects of other jammers with such a general calculator. We would need very detailed radar and jamming simulator to evaluate jamming effects.

With the same duty cycle, detection range is longer by 12% if pulse width is the main contributor instead of PRF. Why?

hornetfinn wrote: I don't think there is a way to simulate effects of other jammers with such a general calculator. We would need very detailed radar and jamming simulator to evaluate jamming effects.

Yes... and no.
Just like any other calculator the basic formulaes are (rather) simple and can be put in excel. I have used a few of those and they work fine. The problem is to know the caractheristics of the jammer. Ant that is something you won't find on the net.

regards.

eloise wrote:With the same duty cycle, detection range is longer by 12% if pulse width is the main contributor instead of PRF. Why?

Because the amount of energy delivered to target and then back to radar is a product of transmitted power and duration of pulse. So radar gets more powerful return signals when pulse width is longer. Higher PRF improves detection range to some degree, but pulse width affects range more. Of course things are not this simple and longer range is not always really wanted since it can affect other performance factors too much. Best overall performance is usually achieved by balancing PRF and pulse width.

Is the difference between 50% and 90% PD not too large?

eloise wrote:

sprstdlyscottsmn wrote:I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.

The first one is volume search
The second is cued search, so the detection range get much longer just like hornetfinn said.

When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

So even a small AESA Radar like the RBE2 AESA must have a superior range.

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Where did you get this from?

terrygedran wrote:

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Where did you get this from?

https://www.revolvy.com/main/index.php?s=Irbis-E

90km maximum detection range (and most likely those are at its highest power output, narrow beam, and no electronic interference) against a 0.01sqm target. Still wont be that meaning full of detection range against VLO aircraft like F-22 and F-35...

terrygedran wrote:

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Where did you get this from?

Take a look at Hornefinns post. Theres is also a link to official Russian site. But it dosnt work anymore.

viewtopic.php?f=38&t=52962&p=372755#p372755

swiss wrote:

terrygedran wrote:

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Where did you get this from?

Take a look at Hornefinns post. Theres is also a link to official Russian site. But it dosnt work anymore.

viewtopic.php?f=38&t=52962&p=372755#p372755

Strange, it still works fine for me with different browsers. Can anybody else get to that UAC site? Anyway, those specs have been published in several different places, including NIIP and they are also consistent with radar theory. Narrowing the search area significantly allows also significant increase in detection range and that works with any radar. Downside naturally is that the target must be detected and actually tracked by some other sensors fairly accurately for it to work. Otherwise it would need a lot of luck to catch anything. For example AN/APG-81 can probably use cued search also and can probably have vast range improvement over normal volume search.

hornetfinn wrote:
Strange, it still works fine for me with different browsers. Can anybody else get to that UAC site? Anyway, those specs have been published in several different places, including NIIP and they are also consistent with radar theory. Narrowing the search area significantly allows also significant increase in detection range and that works with any radar. Downside naturally is that the target must be detected and actually tracked by some other sensors fairly accurately for it to work. Otherwise it would need a lot of luck to catch anything. For example AN/APG-81 can probably use cued search also and can probably have vast range improvement over normal volume search.

Its really strange, know its works.

Im curious. Where the Russians always behind in Radar-technology? Or was there a time when the Russians AF were on the same level with the US Fighters?

charlielima223 wrote:90km maximum detection range (and most likely those are at its highest power output, narrow beam, and no electronic interference) against a 0.01sqm target. Still wont be that meaning full of detection range against VLO aircraft like F-22 and F-35...

I'm not sure that you actually mean but the F-35 RCS is not 0.01 sqm target but instead it is 0.001 sqm target (there one more zero between the 0 and 1 in decimal places). That makes all the difference and as such there's no way that an Ibris-E can detect a F-35 at a distance of 90 km.

Or even an order of magnitude or more lower:

On a radar map, a 747 would appear the size of a hot air balloon and an F-16 would look like a beach ball. Drill down to legacy stealth aircraft and Lockheed’s F-117 Nighthawk would show up as a golf ball while an F-22 Raptor might appear as a pea. With the F-35, Lockheed is getting down to pebble size, according to Robert Wallace, senior manager for F-35 flight operations.
Wallace, a former chief of low-observability for the US Air Force’s B-2 bomber, says the F-35 has leveraged LO qualities from the bomber – but he could not elaborate on specifics.
Pilots will see a more advanced low-observable signature on the F-35 versus the F-22, but it’s the maintainers who see the greatest leap in durability.

https://www.flightglobal.com/news/artic ... -u-432983/

If you take those sphere descriptions literally, we're talking about something like a 5mm diameter (metal) sphere, which mathematically equates to an RCS of -47.07dBm or 0.0000196m^2 (a decimal point followed by four zeros). Obviously / presumably that would be an RCS valley / ideal aspect angle, but if pilots know how to utilise it...

ricnunes wrote:

charlielima223 wrote:90km maximum detection range (and most likely those are at its highest power output, narrow beam, and no electronic interference) against a 0.01sqm target. Still wont be that meaning full of detection range against VLO aircraft like F-22 and F-35...

I'm not sure that you actually mean but the F-35 RCS is not 0.01 sqm target but instead it is 0.001 sqm target (there one more zero between the 0 and 1 in decimal places). That makes all the difference and as such there's no way that an Ibris-E can detect a F-35 at a distance of 90 km.

Even if we assume the F-35 has a RCS of 0.01. With the official Range of 200 km for a 3m2 Target, the IBRIS-E would detect the Lightning II in 48 km. And if Dragon029 is right, maybe a Russian Pilot would see the F-35 first with is own eyes instead on his radar screen.

swiss wrote:Im curious. Where the Russians always behind in Radar-technology? Or was there a time when the Russians AF were on the same level with the US Fighters?

I think they were fairly close in 1950s, but started to lag behind in 1960s and continued to be left further behind. I think the main reason was the fact that they lagged behind in computer technology and especially manufacturing. Soviet government and key politicians made some grave errors in their politics and approach to computer technology which resulted in serious stagnation in technology and manufacturing development. This made it more difficult and time consuming to design new radar systems and their components. For example MiG-23 was always about 10-15 years behind F-4 variants in radar technology. F-4E was introduced in 1967 and MiG-23 got roughly similar radar only in MiG-23ML variant in 1978. Su-27 and MiG-29 were at lower technological level in late 1980s to where western radars were in early to mid 1970s with AN/APG-63 for example.

Of course Soviets were quite innovative and found some ways around their limitations. They designed huge interceptors with sometimes crude but powerful radars (Tu-128, MiG-25, MiG-31).

Today Russia has inherited that history and is also affected by shortage of money for development. They have done fairly well with their limited resources but have not been able to close the gap in technology and manufacturing. Their current radar (and other sensor) tech is at about same level where it was in 1990s in West. Su-35 with the powerful Irbis-E sounds great on paper, but I'd wager the small AESA in Rafale beats it in most capabilities and might even outrange it.

swiss wrote:

eloise wrote:

sprstdlyscottsmn wrote:I seem to recall an old post by Hornetfinn saying that given equal assumptions of target RCS and detection probability that the APG-81 likely matched or exceeded Irbis-E. That second one seems to pan out with that.

The first one is volume search
The second is cued search, so the detection range get much longer just like hornetfinn said.

When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

So even a small AESA Radar like the RBE2 AESA must have a superior range.

I've seen similar numbers. 200km in volume search. 350-400km in very narrow, cued search. Of course we're still dealing with ~50-55% detection rate standards vs 90+% standards for western systems.

Thanks a lot for your explanation horentfinn.

As you said, this make sense, because the Russian where always behind in Computer technology in comparison with the usa and other western countries.

hornetfinn wrote:Today Russia has inherited that history and is also affected by shortage of money for development. They have done fairly well with their limited resources but have not been able to close the gap in technology and manufacturing. Their current radar (and other sensor) tech is at about same level where it was in 1990s in West. Su-35 with the powerful Irbis-E sounds great on paper, but I'd wager the small AESA in Rafale beats it in most capabilities and might even outrange it.

When we talk about current Russain radar, you mean the Russian AESA radars? As you mention in a other tread, the Ibris-E is on the same level as a AN/APG 63 or 70. That would be a tech level from the 1970 or 1980s?

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Tell me what is the probability of detection ?

terrygedran wrote:

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Tell me what is the probability of detection ?

In volume search?

Dragon029 wrote:Or even an order of magnitude or more lower:

Absolutely!

Hence why I said that a RCS value of 0.01 square meter shouldn't be considered for the F-35. Even the 0.001 value square meter is very conservative and a "worse case scenario" for the F-35.

swiss wrote:

terrygedran wrote:

swiss wrote:
When i remember correct, the Range for the ibris-e in volume search is maximally 200 km for a 3m2 target. Or 152 km for 1m2

Tell me what is the probability of detection ?

In volume search?

Yes

terrygedran wrote:
Tell me what is the probability of detection ?

I don't know what the claims are, from the russian Manufacturer of the ibris-e. As far as i understand the probability of detection in volume search is 50%.

ricnunes wrote:

charlielima223 wrote:90km maximum detection range (and most likely those are at its highest power output, narrow beam, and no electronic interference) against a 0.01sqm target. Still wont be that meaning full of detection range against VLO aircraft like F-22 and F-35...

I'm not sure that you actually mean but the F-35 RCS is not 0.01 sqm target but instead it is 0.001 sqm target (there one more zero between the 0 and 1 in decimal places). That makes all the difference and as such there's no way that an Ibris-E can detect a F-35 at a distance of 90 km.

Obviously the (I know) F-35's quoted optimal RCS is much much smaller. I was merely using his 0.01 sqm target as a reference before the diagram.