Can aircraft evade infrared by hiding in contrails?

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armedupdate

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Unread post07 Sep 2017, 21:17

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Civilian and military traffic produce a lot of contrails. Instead of hiding in clouds which are often very low, is it better hide in contrail paths? Or can some spectrum of IR see right through them.
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white_lightning35

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Unread post08 Sep 2017, 00:15

Wouldn't that be a rather bad situation if the f-35 needs to hide in a time and place where civilian aircraft are flying?
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armedupdate

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Unread post08 Sep 2017, 00:40

Contrails last in the sky for hours
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white_lightning35

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Unread post08 Sep 2017, 01:34

I just thought it strange that civilian aircraft would be flying around in a warzone.
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hornetfinn

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Unread post13 Sep 2017, 09:21

I'd say contrails are too thin and far too narrow to really allow hiding behind them. IR can see through particulates like clouds and smoke better (often much better) than human eye can because of longer wavelength. Sure clouds, smoke and also contrails absorb and reflect IR light and make detection and tracking more difficult. But absorption and reflectivity depends on their width, density and particulate size and composition and I'd say contrails are rather thin and low density and/or thus IR systems can see through them pretty well. Another problem is that there is no way of knowing where IR systems are and being able to stay behind contrails is probably rather difficult to do in real life.

I'd say contrails are not very effective or reliable way of evading or even degrading IR systems. Clouds are much more effective because they are usually far bigger physically and have thus more effect on IR and also cover much larger area/volume.
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armedupdate

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Unread post14 Sep 2017, 00:50

hornetfinn wrote:I'd say contrails are too thin and far too narrow to really allow hiding behind them. IR can see through particulates like clouds and smoke better (often much better) than human eye can because of longer wavelength. Sure clouds, smoke and also contrails absorb and reflect IR light and make detection and tracking more difficult. But absorption and reflectivity depends on their width, density and particulate size and composition and I'd say contrails are rather thin and low density and/or thus IR systems can see through them pretty well. Another problem is that there is no way of knowing where IR systems are and being able to stay behind contrails is probably rather difficult to do in real life.

I'd say contrails are not very effective or reliable way of evading or even degrading IR systems. Clouds are much more effective because they are usually far bigger physically and have thus more effect on IR and also cover much larger area/volume.

But don't contrails get pretty thick up high?
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pmi

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Unread post14 Sep 2017, 01:22

Look at the end of the contrails on the far right, and at those of the Migs. Would you say those are persistent enough to serve as cover for practical purposes?
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hornetfinn

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Unread post14 Sep 2017, 06:59

armedupdate wrote:But don't contrails get pretty thick up high?


They seem thick to human eye, but in IR it's different. Look at this video:


or this:


You can see that even very thick smoke is not much of a problem for infrared systems, but water mist definitely is (latter video). This is because smoke particles are very small, but water mist particles are much larger. I think contrails are much closer to smoke (in particle size and density) than water mist and thus affects IR systems fairly little.

Another problem is that the contrails are not very wide and thus hiding behind them in a fast jet would be very difficult even if there was only one IR system and its position is known. Neither is likely in real life situation.
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armedupdate

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Unread post14 Sep 2017, 08:18

The problem is the sky is littered with contrails and can be see on IR sats from space.
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hornetfinn

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Unread post15 Sep 2017, 08:56

armedupdate wrote:The problem is the sky is littered with contrails and can be see on IR sats from space.


Problem for what? Sure those contrails can be seen on IR, but that doesn't mean they are very effective hiding aircraft.

That image is clearly SWIR which is very close to visible light because it works with light reflected or absorbed by the object (unless it's extremely hot). For long range detection (like IRST/FLIR systems) MWIR or LWIR (or both) are used. They are very different to SWIR in operation and what they see. MWIR and LWIR see through clouds, smoke and also contrails much better because they work using the infrared radiation coming from object itself. Those contrails would cool down very quickly and be fairly transparent in MWIR and LWIR region. A fighter aircraft behind contrail would be much warmer and have much higher thermal radiation intensity and would be seen easily behind the very cool contrail.

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