IRST vs Raptor

[icemaverick]

I don't usually pay attention to the comments section on Youtube because it is often filled with idiocy....especially in videos concerning fighter aircraft. However, it caught my attention that a lot of proponents of non-LO aircraft (e.g. EF, Su-30 etc.) seem to put a lot of faith into modern IRST systems. They'll acknowledge that the Raptor will detect their favorite aircraft by radar first. But they seem to believe they can detect the Raptor at 100 km ranges with systems such as PIRATE.

Do we have any idea of how credible this is? I know that PIRATE can detect targets at up to a range of 100+ km, but that's probably assuming perfect conditions. Also, the Raptor probably has more IR reducing measures than most aircraft. Are there ways to confuse or "jam" an IRST system? What is the effective range of a missile guided by an IRST? Is it possible to score BVR kills at ranges comparable to radar guided missiles?

[pants3204]

The OLS-35 provides a coverage of +/-90 in azimuth and +60/-15 in elevation with a target acquisition range for non-afterburning aerial targets of 50 km facing up to target's front hemisphere and 90 km facing up to rear hemisphere. The laser rangefinder features a five-meter Circular Error Probable (CEP) and ranges up to 20 km for aerial targets and 30 km for targets on the ground.

The more realistic range is 24km frontal, 55km front/side in ideal weather conditions for the Su-35.

http://www.deagel.com/Navigation-and-Ta ... 26001.aspx

[wrightwing]

I don't usually pay attention to the comments section on Youtube because it is often filled with idiocy....especially in videos concerning fighter aircraft. However, it caught my attention that a lot of proponents of non-LO aircraft (e.g. EF, Su-30 etc.) seem to put a lot of faith into modern IRST systems. They'll acknowledge that the Raptor will detect their favorite aircraft by radar first. But they seem to believe they can detect the Raptor at 100 km ranges with systems such as PIRATE.

Do we have any idea of how credible this is? I know that PIRATE can detect targets at up to a range of 100+ km, but that's probably assuming perfect conditions. Also, the Raptor probably has more IR reducing measures than most aircraft. Are there ways to confuse or "jam" an IRST system? What is the effective range of a missile guided by an IRST? Is it possible to score BVR kills at ranges comparable to radar guided missiles?

100km is a bit optimistic for an IRST to detect an F-22, but even if we assume that to be a realistic figure, the F-22 will still enjoy a 2x to 3x detection range advantage versus a Flanker(or other 4th Gen/earlier aircraft).
Another important consideration is that even if the IRST detects a target at that range, it won't be able to provide targeting information to a missile, until it gets much closer.

[pants3204]

I've also heard fanciful claims of the Su-35's IR MAWS system is capable of detecting BVR missile launches, but that doesn't really make much sense considering it is beyond visual range and thus beyond IR's detection envelope. How prone is the F-22 to radar detection when engaging a target with an AMRAAM and how susceptible is the AMRAAM to detection via radar? Another common assertion is that the Su-35 can out maneuver the AIM-120 anyways making the F-22's BVR abilities moot.

I believe these people are incorrect but I don't know what information to show to them to prove my point.

[wrightwing]

I've also heard fanciful claims of the Su-35's IR MAWS system is capable of detecting BVR missile launches, but that doesn't really make much sense considering it is beyond visual range and thus beyond IR's detection envelope. How prone is the F-22 to radar detection when engaging a target with an AMRAAM and how susceptible is the AMRAAM to detection via radar? Another common assertion is that the Su-35 can out maneuver the AIM-120 anyways making the F-22's BVR abilities moot.

Anybody claiming that the F-22's BVR capabilities are moot, are grasping at straws. The Flanker is a good plane, but hardly invincible. I wouldn't want to deal with an AIM-120C/D or AIM-9X, whatever the pamphlets say.

[fat_cat]

IRST vs Raptor, or for that matter any aircraft? Just don't mention those pesky things called clouds.

[BDF]

The F-22’s IR signature management is probably the least known in public circles. The only thing known concrete is the TOPCOAT developed by Boeing which is a specialized paint that contains various elements including silver which gives it that distinctive sheen. Not much is known how TOPCOAT works but it’s generally thought to be selectively emissive; i.e. it shifts the surface’s emissions to areas that easily absorbed in the atmosphere such as the 3-8um band. It may also absorb or suppress the total overall emission across most bands. The jet also has a fairly small exposed area around the engine nozzles and may employ some active cooling around the engine bay (air heat exchange probably) to reduce the signature from hot engine components as well as a flat exhaust which helps the exhaust stream mix and cool faster in the atmosphere (smaller IR “tail”). Finally, the F-22 has also been purported to employ leading edge cooling on the wings (and vert stabs?) to keep those large surfaces from building up too much heat.

The problem with IRSTs is that most brochure stats are that those are cued detection ranges. IRSTs generally aren’t well suited to volume searches because of the fairly narrow field of view from the sensor; I’ve heard it described as “looking through a soda straw”. So in this case the sensor is cued by another sensor to stare that that particular point in the sky. I’ve also heard too that in practical terms you should take brochure ranges and subtract roughly a third off of that to arrive at a more reasonable “real world” figure. Even then you’ll still have problems with target ID and developing an engagable track as at long ranges target detection is just a blob and even with passive ranging techniques or cooperative tracking (multiple platforms tracking the target) you will have just a smear track and it usually requires the range to come down significantly before the accuracy of the track increases to the point of being able to engage and support a weapon inflight.

[pants3204]

Hey thanks for all of that information BDF. It's difficult to find these kinds of things online.

Also, I presume you're talking about spectral band emissions, since blackbody emissions shorter than 8 micrometers correspond to temperatures above 90 degrees C (190 F).

[river_otter]

I've also heard fanciful claims of the Su-35's IR MAWS system is capable of detecting BVR missile launches, but that doesn't really make much sense considering it is beyond visual range and thus beyond IR's detection envelope.

Detection depends on the signal to noise ratio more than raw signal strength. When you see a hot pixel, is that a signature, or thermal noise? You have to balance missing the pixel against picking up so much noise that everything is a hot pixel, and you still don't see the real hot pixel. For example, taking the same flashlight, you will be able to see it from farther away at night than at noon, even though it's the same flashlight. Relative to visible light, IR benefits from a low background in the sky most of the time. Picking up a rocket's exhaust at 4000C against air at -40C gives a better S/N ratio than seeing a matte grey airplane against blue sky and grey clouds. Or an unlit airplane against an unlit night sky. The missile is the flashlight at night in IR, but the flashlight at noon in visible light. So even though IR gets absorbed by the atmosphere far more than visible light does, there's less of it you have to discriminate the launch out of, and you can detect a missile launch using IR much farther away than what would be considered WVR.

It's still far, far short of the detection range an AN/APG-77 will have against a plane. With radar, you can put out a tremendous illumination beam at frequencies the atmosphere doesn't really absorb, and nothing else in the sky will reflect anywhere near as much of that beam as most planes will. And the amount of stray radar energy filling the sky around the plane is so nearly zero it makes even the IR background look like high noon. AESA practically guarantees that stays true even when a powerful jammer is operating. It will frequency hop almost at random 40+ times per second, and no jammer is going to be able to flood the sky with several MW of radar energy in each frequency slot across that whole spectrum simultaneously. In at least some frequencies the radar will hop to, the radar will illuminate the target's area of sky with a huge amount of energy against a zero background, and only the target will reflect an appreciable amount of that energy back. Huge signal plus very low noise equals massive advantage in detection range over the best possible IRST.

[wrightwing]

It will frequency hop almost at random 40+ times per second, and no jammer is going to be able to flood the sky with several MW of radar energy in each frequency slot across that whole spectrum simultaneously. In at least some frequencies the radar will hop to, the radar will illuminate the target's area of sky with a huge amount of energy against a zero background, and only the target will reflect an appreciable amount of that energy back. Huge signal plus very low noise equals massive advantage in detection range over the best possible IRST.

I agree with your conclusions, but the APG-77 hops freqs at >1000 per second, making it very difficult to jam. This is also one of the reasons why it works well for LPI too.

[g3143]

I forgot where i read this was but was not the f-35 tested to be able to detect and jam the f-22 radar? Does any have any info on this?

[southernphantom]

I forgot where i read this was but was not the f-35 tested to be able to detect and jam the f-22 radar? Does any have any info on this?

I have never heard of this claim; the F-35's avionics are very much a work in progress. Maybe it can, but the software to do so has probably yet to be loaded onto an airframe.

Also, the F-35 hasn't actually had any mock-combat evaluations, and won't for a while.

[g3143]

I forgot where i read this was but was not the f-35 tested to be able to detect and jam the f-22 radar? Does any have any info on this?

I have never heard of this claim; the F-35's avionics are very much a work in progress. Maybe it can, but the software to do so has probably yet to be loaded onto an airframe.

Also, the F-35 hasn't actually had any mock-combat evaluations, and won't for a while.

Found the article:
http://www.aviationweek.com/aw/generic/ ... 281824.xml

[southernphantom]

Fair enough. I was technically correct, but I forgot about the CATBird. That is one sweet aircraft, my dad's former employer was actually doing some MX work on her less than a year ago.

[sprstdlyscottsmn]

Yes CATBird. A Boeing 737 that can track satellite rocket launches from 800 miles and can jam raptors... How many AMRAAMS can it hold? Just kidding.