IRR, testing & proofing

Discussion in 'Weapons, Equipment & Rations' started by Gook, Dec 9, 2005.

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  1. Alright, theres a lot of talk of which brand of kit is IRR, and which might not be, and what might end up getting you slotted in exchange for a 50-beertokens-cheaper price tag at Soldier of Fortune. So how does the enterprising young infanteer actually find out if he's been had or not?

    How can you test something for IRR-ness? Its not as simple as just looking through a CWS at it, is it? Because I've used one of those around guys with some considerable nonissue kit and the image of woolly hats, softie jackets and webtex vests isnt yet burnt into my retinas... Do you need an IR illuminator, whatever that is?

    Älso, say I've got a piece of nonissue kit I dearly love, ie. dont want to ditch in exchange for the shittier issue version, however don't fancy being as obvious as a man smoking endless cigarettes through a luminous balaclava to any en with NVGs. How the hell can you make it IRR?

    Is there a treatment maybe you can wash it in, like fireproofing something, as I seem to remember hearing that veh cam nets were treated with some chlorophyll chem to make them appear more like foliage through II or IR night vision. Or is it simply IRR or not from when it is made in the factory, and beyond hope?

  2. 307

    307 War Hero

    The way I always thought it was is that IRR stuff is meant to suppress the release of infra red light from your body to make you less visible to night vis that pics up IR light. BUt I always thought, say you're wearing 95s and then a webtex vest, the 95s should suppress your IR signature, so surely the vest not beign IRR doesnt make all that much of a difference?
  3. IR is still light; we just can't see it unless we get a little help from some equipment. We do radiate IR radiation as heat, but it can also be reflected, from our clothes gear etc...

    So if there is any source of light present, say the moon, then your non-IRR kit will reflect the IR as well.

    Hope this makes sense... I didn't want to get into the scientific nitty-gritty bits about how different materials reflect different wavelengths of light etc etc but if u want to pm me I can go into a bit more detail.

    AS for treating kit, I have no clue.

    T C
  4. I may be wrong here, I often am. I was led to believe that IRR kit was designed to be effective against the old active IR systems so doesn't work too well against later passive systems.
    As for TI then IRR is a non starter..
  5. If something is anti-active, surely it'd be anti-passive too? I may be talking utter rubbish, but doesn't passive mean it just watches/listens, while active, like sonar, needs a light source or a 'ping' to work?
  6. There are 2 forms of IR energy - near IR (what we see through NVGs) and far IR (commonly known as 'Thermal Imaging'). Perhaps overly simplistic - but essentially true.

    The vast majority of heat energy lost by the human body is in the form of radiation. This is where traditional, mass insulations fail; they only address two of the three mechanisms of heat transport, which are conduction and convection.

    Traditional, mass insulation does little to stop heat loss by radiation. As the human body emits heat, traditional bulky insulation can only absorb so much heat and then it is re-radiated to the cold outside.

    Adding more insulation isn’t the answer to staying warm. In some cases, adding more insulating layers can make the wearer even more uncomfortable, not to mention, more expense. By adding more insulation, wearers will store more heat, only to be re-radiated to the outside and away from the body, where it’s needed.

    There are three modes of heat transfer: conduction, convection, and radiation (infrared range). Of the three, radiation is the primary mode; conduction and convection are secondary and come into play only as matter interrupts or interferes with radiant heat transfer.

    All substances, including air spaces and materials, such as fabric and insulation, obey the same laws of nature and transfer heat. Solid materials differ only in the rate of heat transfer, which is mainly affected by differences in density, weight, shape, permeability and molecular structure. Materials which transfer heat slowly can be said to resist heat flow.

    Direction of heat transfer is an important consideration. Heat is radiated and conducted in all directions, but convected primarily upward.

    Therefore, CS95 is not designed to prevent the radiation of thermal energy, as it would prove to be too bulky or too warm at appropriate levels of protection. That said, the new sniper suit does afford thermal protection.

    Looking at the near IR - or the way people look 'green' at night. CS95 is given a proofing of agent that reduces its ability to reflect light in the near IR (1 -3 microns). We perceive the scene as 'green' because the photocathode tube is lined with phosphorus - hence the colour.

    It is always a balancing act when trying to reduce IR signatures. If we go too far, we create 'black bodies' - look at a window through a TI for an example of this - helicopters are particularly susceptible - as the relative coldness of the sky is reflected in the glass. This is called 'cold sky reflection'.

    In summary:

    1. CS95 is designed to reduce the reflectivity of the material in the near IR band.
    2. To reduce the thermal signature would result in clothing that was too bulky and warm.
    3. It is theoretically possible to proof your own clothing, but at disproportionate cost.
    4. Wearing non-issue kit in the face of a technologically advanced enemy is silly - 'bright' targets attract bullets.

    Hope this helps someone.
  7. Firstly I am a PET OP so if Im that close to the enemy then its all gone Pete Tong
    Secondly Due tohealth and safety we have to use lights to work at night so the enemy can see me anyway, so wearing issue or non issue kit doesnt change anything for us.
  8. Thats me, wrong again.... :lol:
  9. Well said DD...
    Was what I was trynig to say, but you put it much better.

    T C
  10. Okay then so basically non IRR stuff will not make you stand out to Image intensifiers (passive right?) which is what most people use...

    It only makes you vulnerable if someone shines an active IR source, but in that case they are easily spotted and dealt with...

    Plus if they have active IR illumination, they'd likely have Thermal imaging so you're fcuked anyhoo...

    Or am I misunderstanding?
    Gook out
  11. Gook - 'non IRR stuff' will make you shine with reflected ambient light like a Christmas tree when viewed through a near IR imager. This is the case regardless of whether you are illuminated with an active source (a la IR torch) or moonlight (or other ambient light source).

    Clothing impregnated to reduce the IR reflectivity will 'damp down' your image on the screen and make you look 'darker'.

    Summary: non issued kit purchased from the High Street will make you a better target at night to an appropriately equipped enemy than a soldier wearing issue kit.
  12. So the DPM thong the wife got me from M&S is a non starter then..
  13. 307

    307 War Hero

    Anyone know if theirs truth in the fact that regular washing and ironing of kit reduces the IRR level of it?
  14. well if they fade, the IRR qualities of the material must change