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- Survival - Learn How To Hide From Airborne Infared Detection Devices, Snipers Guide
- In Hot Tips & Cold Shots.Fieldcraft.Thermal Detection, there are some
- pretty gloomy postings about IR detection. As an
- electrical utility thermographer, I might shed some light (pun intended) on
- the subject. To qualify this, I am using the latest (I
- think) commercially available FLIR product, and am a level II thermographer,
- (total formal IR training: 2 weeks-experience
- using IR equipment: about 5 years.) I believe I am at least familiar with
- IR. Granted, my life is not depending on avoiding IR
- detection, so I guess I can have my opinions pretty safely. These are my
- observations about IR imagers using civilian
- equipment and are.. "just my opinion". It's up to you and yours to check
- them out in your world.
- This is WAY brief, believe it or not. Anyone interested can email for
- more. This is about THERMAL detection, not IR
- illuminating sources for "starlight" scopes.
- IR is not Xray, Hollywood bedamned-it cannot detect a differential heat
- image through common solid materials, plastic
- film (black or otherwise) being an exception. However, a good imager system
- can see through holes in a masking material
- ("IR masking" camo net). And if you are inside a dumpster, bodyheating the
- bad guy's side, he can "see" the hot spot on the
- dumpster's outside. But if you are not leaning (heating) against that side,
- he can't "see you". Your body heat will not be
- detected behind most readily available unholed blinding materials if you are
- not differentially warming/cooling those
- materials or allowing your own IR to reflect off of something behind/over
- you. BUT, if the shielding materials are alien to the
- surroundings, the material itself will probably stand out. See below.
- Glass will not allow your THERMAL image to transmit (pass) through; same
- as the dumpster scenario. The lenses of IR
- imagers are made of exotic nonglass materials because of this.
- Every piece (cluster) of matter, including gasses, emits IR if it is
- above Absolute Zero (minus 459.69 degrees F). The
- warmer a body gets, the more IR it will emit. Eventually it will enter the
- visible spectrum as it gets "red hot".
- The surface of a piece of matter is where IR is emitted. Altering an
- object's surface will alter the rate at which IR is
- emitted. Stoveblack is a classic example.
- Materials physically different from each other will likely emit IR at
- different rates. BUT the differences may be very slight.
- IR imaging (read DETECTION) depends upon two objects having one or more
- differences in Temperature,
- Emissivity/Reflectivity, and Absorption of the compared objects. For this
- application, we can forget about Absorption, and
- you should all understand Temperature. Now, E + R = 100%, thus the more
- emissive a surface is, the less reflective. If two
- dissimilar objects are at the same temperature, a high E will "look" hotter
- to an IR imager than a low E, thus forming an
- image. Objects with different Temperatures and the right E's could "look"
- the same, thus forming NO image. Two objects
- with similar temperatures and similar emissivities will present an unclear,
- poorly defined image. Herein lies your IR strength.
- Here are some Emissivity values for a few materials, all in percents,
- all plus/minus a point or two. These are for short
- wavelength commercial imagers and may vary slightly for long wavelength/long
- range military/LE equipment. Military techies
- should have similar emissivity tables for your equipment.
- Human skin
- : 97
- Black vinyl electrical tape
- : 97
- Surface sprayed with Dr. Scholl's aerosol foot powder
- : 96
- Water
- : 95
- Rubber, black, hard
- : 94
- Glass, smooth
- : 94
- Plywood, raw lumber
- : 90-95
- Most painted surfaces (NON aluminum paint)
- : 90-95
- Aluminum based paints, depending on formula
- : 30-50
- Oxidized (blued, parkerized) steel
- : around 90
- Snow
- : 82-85
- "Most" organics (vegetation)
- : around 80
- Cloth, untreated
- : around 80 (Cotton
- was a plant too)
- BDU fabric, treated
- : ????????? I
- would like to know.
- Sand
- : 76
- Clay
- : 40
- Gravel
- : 38
- Aluminum, bare and "shiny" (read "spaceblanket")
- : under 10
- Note the materials that cluster around 95, 80, 40, and 10
- Now, to apply IR-101: In all of the scenarios below, remember that your
- body (or ANYTHING above absolute zero) emits IR
- in ALL directions. If there is a reflective object behind or beside you, it
- will pick up your IR and reflect it like you were a light
- bulb. Whichever situation and methods you use, if you have the opportunity,
- have an ally check you out from a flank with
- your best IR detection equipment. Or get the flyboys to check you out with
- FLIR's namesake. Do this by day AND night, as
- the sun will do weird (but predictable) things to the differential temps.
- The BEST way to protect yourself from IR detection is get behind/under
- what is already there, and DON'T change the
- temperature of it. Since you obviously have to see and perhaps reach out,
- do so through the smallest portal(s) you can
- handle. Those "man-sized" targets detectable at 1100 yards are just that -
- man-sized - not the size of your nose and right
- eye. Remember that glass reflects some IR (100 - 94 = 6%), and the sky
- (space) is cold (approaching Absolute Zero), so if
- your scope is reflecting not sun, but sky, it will look COLD. If you have
- on a scope sunshade that is hot, the internal IR of the
- sunshade will reflect out as HOT.
- I believe the GI Woodland BDU's are treated with an IR emittance
- reducer. If so, the "cloth" E figure in the table will
- change and you have to adjust for the following discussion. Or obtain
- untreated camo fabric or defeat that treatment (starch,
- I believe). The IR reducing treatment makes sense for a situation where the
- woods is cooler than 98.6 F. I hope the Desert
- Daylight BDU's are NOT treated, but the nighttime anti-starlight smocks
- probably should be. If your BDU's image "cold"
- against hot sand, you are just as "seen". I trust the techies were aware of
- this, and have specified correctly. But you need to
- confirm by looking through your equipment at your buddy against some typical
- backgrounds.
- It has been reported that "fresh" BDU's do indeed have an IR treatment
- that fatigues (pun) with laundering in "brightener"
- detergents. As a hunter, I am aware of the UV problem with animals with
- good night vision (is it an overabundance of rods, or
- cones, in the eye?) and there are detergents available via sporting goods
- stores that do not contain brighteners. If you need
- to maintain that BDU treatment, you might try that. But again, look at your
- buddies with your equipment.
- Now, in sand or vegetation (E = 76-80): If you HAVE to have artificial
- cover for situations where your clothing will
- approximate the temperature of the surroundings, you want to expose matching
- temperature "stuff" with a similar E (around
- 80). Cover as much of your skin (97) as possible with cloth (80) (remember
- that I don't know the E for treated BDU's). But
- also remember that sweaty cloth in a hot, dry background might look cold due
- to evaporative cooling. If you are in a hot dry
- situation, a tented, solid (not net), dry camo fabric applied as a screen
- might do the trick for IR. (Remember, same T, similar
- E). Visual is another problem. Keep the outlines irregular for both IR and
- visual. Square stuff in a curvy world stands out, no
- matter the technology. Fresh local vegetation in front of the screen will
- help both.
- Camo face paint is PROBABLY a high emitter, similar to regular paints
- (90-95), and sweat (water-95) is for sure. You really
- have to keep that face behind something. I don't know what a synthetic ski
- mask would have for an E, but I bet it is below
- 97. A plain old cotton tee shirt mask would work, but remember the
- wet/dry/cooling problem.
- Black ANYTHING is a good emitter. Blackened steel barrels, synthetic
- stocks, and painted surfaces (all E's in the 90's)
- should be cloth wrapped for IR and visual both. Black SWAT uniforms
- probably have a higher E than camo. You need to test.
- Dry rubber boot soles (94) are nearly as hot as your face - sock 'em (80).
- Old cut local vegetation will be drier, thus HOTTER due to lack of
- evaporation.
- The name of this game is to keep both the Emissivity and the Temperature
- of the screen and clothing the same as that of
- the surroundings and keep those portals small.
- If you are on bare clay or gravel (38-40) and are worried about aerial
- observation, dig in. Cover yourself with almost
- anything sufficiently rigid and then cover it with at least a thin but full
- layer of the local "dirt". This will match the E's. Once
- the moisture of the new cover layer equals the moisture of the surface
- around you (evaporative cooling), you will be in decent
- shape IR wise. Remember that these low E materials have a high
- Reflectivity, so block your own IR from getting out from
- under the cover. If there is a chance your body heat will affect the top
- surface of the dirt cover, use insulating material
- between you and the bottom of the "roof" to keep it the same temp as the
- ground around you. Foam board or sleeping bags
- will do that. The most critical times of day for this hide would be as the
- sun changes, because rapid heating/cooling of a thin
- layer of dirt will show up compared to the slower heating/cooling of the
- intact soil masses. If you can set up in a shaded spot
- where this will not occur, you should be in decent shape. If there is no
- shade, make the cover layer thick to create a heat
- sink approaching that of the surroundings.
- If there is no threat of aerial observation, and it is only a frontal
- threat, a "wall" of local dirt with small portals would be the
- best bet.
- Any new foxhole will print either hot or cold depending on the season
- and surface temperature, even if the surrounding soil
- is bare. The deeper soil temp is probably closer to 55 F than the surface.
- On snow (82-85), build a snow fort or tunnel in and make small portals.
- Try to dust loose snow to duplicate surface
- texture. Pray for new snow. If you wore an aluminized face shield behind
- that snow fort, it would reflect the "cold" off of the
- fort, and cover your hot face. This might be a shiny side application of
- the space blanket, and could be worth testing. Water
- (95) is your breath when it condenses. And it is warmer than the snow.
- Only thing I can think of to do here is breath through
- a ski mask and let it condense before it fogs up over your screen.
- As to "space blanket" applications: there might be some, BUT. If you
- are using the shiny side toward you to keep your IR
- from getting out, remember that the backside of it is probably not a good E
- match to the surroundings and it will heat/cool a
- lot differently than most natural things around you. If you are trying to
- put the shiny side out angled down to reflect the IR of
- the terrain right in front of you, there would be a 10% reduction in the
- reflection, more if it casts a shadow. If the shiny side
- is out and up, it will reflect the cold of outer space (or the heat of the
- sun) - and it is going to look REALLY weird to visual and
- starlight in EITHER case! I cannot think of a space blanket application
- that I would stake MY life on.
- In an urban situation, you will have lots of "normal" IR blockers to get
- under/behind. Just remember that you are an IR
- light bulb on the cold surfaces behind you. You cannot casually set up back
- in the room shadows of a windowless building
- anymore. Remember, glass will NOT pass through (transmit) your IR image.
- BUT, glass (94) has a high emissivity and will
- show its surface temperature rather well. If you are near the window
- warming it with your breath, you will reveal yourself. If
- you had a small barrel portal through an otherwise intact glass window, you
- would be IR blocked, but visually seen. A loose
- pane of glass back in the room shadows might be a possibility, especially
- for a spotter. If the room is painted (90-95) and
- warm (approaching 98.6 F), you might blend in IR wise. But if there is one
- warm window/room in an "empty" building,
- something is amiss. The painted walls behind you might not reflect your IR
- really well, but a metallic light fixture might blink
- every time you turn your face toward it. The best I can imagine is forget
- about the "room" and get behind/under something
- that should be there - sofas, chairs, drapes, etc. and keep your portal
- small.
- None of the above CONCEALMENT strategies are easy; none are guaranteed
- to make you disappear to an imager. But they
- will all help make you a less vivid IR image, thus less detectable. IR
- imagers may or may not have an adjustment to key in
- the emissivity for scanning and reading temperatures. I doubt military/LE
- targeting devices would have that - you don't care
- what the actual temp is, you just want to see a picture. Military/LE
- devices probably have a temperature range adjustment to
- scale up/down according to environment. They probably have an adjustment to
- set the sensitivity - the difference in
- perceived T to go from black to white (dark green to light green; whatever).
- If this is finely tuned, it is like upping the
- contrast on your monitor.
- There is one comforting thing to consider: unless you are in the desert,
- there are a lot of different "things" around you,
- each of them with a slightly different Temperature and Emittance
- combination. If you can make yourself "nearly" match the
- most common IR surroundings and the sensitivity is set very high in order to
- pick up your small T/E difference, the other guy
- is seeing a lot more clutter around you, so your image will be just one spot
- on the Dalmatian.
- For the Ghillie fans: A man sized wad of only burlap and jute rope at
- 98.6 F plus or minus a few degrees will have the same
- E all over it. But if there was some leafage from an IR blocking camo net
- on one shoulder and a splotch of shredded BDU's at
- the waist and some foreign force camo material shredded in there somewhere
- in a cluster, all well supplemented with local
- veggies, from an IR standpoint it would look like a pile of dissimilar
- "stuff".
- If you have gotten this far, perhaps a little DECEPTION is in order to
- up your advantage.
- Remember that "Sarge WILL find something during an inspection, so ya
- might as well give him something so he will stop
- looking." If you want to determine if indeed IR detectors are out there,
- you might want to give them a cowboy hat to shoot
- at. I don't know what the E of a bare GI plastic canteen is, but if you
- either wrapped it with Scotch 33 electrical tape (97)
- from a demo/como kit or sprayed it with foot powder (96) from your ruck, and
- had 98 degree water (coffee? Body heat?) in it,
- it would make a darned good human face (97) to a distant IR imager. Topped
- with a BDU hat and moved about on a stick
- behind some intentionally inadequate screening after dark (by somebody else
- behind that cowboy's large rock), I suspect you
- would soon know the targeting capabilities of the opposition - and also
- acquire a muzzle flash. A piece of most anything
- warmer than the terrain drug remotely through the grass at night should get
- IR attention. Just don't pull it all the way to your
- position. But you get the idea.
- If you want to just give him/them something to worry about, scatter some
- old tire shreds (94) around at points distant from
- your position. They will look hotter than most surroundings when they are
- actually the same temperature. Plus, they will
- heat up more during sunlight, and hold their temperature for quite a while
- into dusk. If you can make them move a bit, so
- much the better. If they are behind intentionally poor screens, thus not
- visually or starlight identifiable, so much the better.
- This would be a great application for decoys specially made for the
- purpose - a visually camo'd, high E lollipop on a spindly,
- flexible stick.
- One of the new IR illumination chemlights would do something, but I have
- no experience with them. I suspect one of them
- tripped off in front of or to the side of your position, yourself in a
- shadow from it, would blind any thermal imagers looking at
- you - like a trip flare would blind a starlight. Obviously this would be a
- defensive action.
- There have been some pretty impressive demonstrations of the
- capabilities of IR equipment. And it is indeed impressive
- stuff, but it ain't magic. It can image warm footprints on a cold roof, or
- a "ghost" where you leaned against a cold wall and
- walked away. But those images fade pretty quickly - faster than the grass
- will spring back up on your trail to a nest.
- I believe that if one person takes the time to study and understand the
- theory of IR systems and applies it to likely
- circumstances in his world and does it better than the other guy does, the
- first guy has an EXCELLENT chance of being the
- winner. That is true for sniping or bidding on a roof inspection. Even an
- unfavorable tilt in sophistication of equipment may
- be overcome with intelligent application of ingenuity. And it won't take a
- lot of formal training. After that, it is experience
- behind an imager. In your case, looking at your buddies in drill hides, and
- correcting each other's errors. I grant you that my
- "thermacam" is not a military targeting device, but if your life is
- professionally depending on IR avoidance, I hope you have
- access to IR theory training and support along with the opportunity to drill
- with your own imagers.
- A rambling closure:
- Overheard among the French crossbowmen at Crecy, 1346AD: "If we go
- against the Smoking Demons, we will die."
- Letter from a Confederate camp, 1864: "The Yanks have put spectacles on
- rifles. There ain't no way to avoid a bullet from
- a mile away."
- NOT to be uttered by my youngest son, USMC Security, Kings Bay NB, 2000:
- "If they've got IR, we are &^%#(+'d!"
- If you may be exposed to a "new" technology, you just have to learn it
- and apply it. Like you did for visual and starlight. In
- fact, most of those old rules apply to IR: Irregular outlines.fresh
- vegetation.local materials.etc. The only real new rule is
- "Similar E - Similar T". Now, get with some equipment and TRAIN, DRILL,
- EXAMINE, Train, Drill, Examine, train, drill, examine.....
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