1. #1
    Bewolf's Avatar Senior Member
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    Just curious. here and then I read about IIFF systems in ww2 aircraft. Always wondered about it a bit and I've never been successful in finding more about it on the net.

    So my question is, is anybody here a bit more knowledgeable in this regard? How did IFF work in WW2, what nations used it in what way and aircraft and so on.

    Ansswers are much appreciated.
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  2. #2
    They used a proven system called Mk.I Eyeball.

    Sorry, couldn't resist. I think there was some kind of radiosystem, but I'll have to dig deep.
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  3. #3
    I may be wrong, but I believe that the first to use an IFF system was the German night fighter force.
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  4. #4
    hop2002's Avatar Senior Member
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    The RAF went live with their first IFF system (codenamed "parrot") on 1st Jan 1940.
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  5. #5
    Bewolf's Avatar Senior Member
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    Originally posted by hop2002:
    The RAF went live with their first IFF system (codenamed "parrot") on 1st Jan 1940.
    How did it work, and what aircraft used it for what roles?
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  6. #6
    hop2002's Avatar Senior Member
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    The IFF set picked up the radar transmission (only on one particular frequency, to begin with) and rebroadcast it, with (I believe) rising modulation.

    They started with Mark I, which only worked with the Chain Home radar system, then switched to Mark II, which also worked with Chain Home Low and the army and navy search sets. Mark II was expanded to cover the various airborne radars as well, but there was a limit to the number of different frequencies it could operate on, so they switched to Mark III.

    The Mark III worked on a single band, rather than responding to each different radar, so it worked with any compatible allied radar.

    The IFF response could also be adjusted with a dial, to give different return signals, but normally only the standard signal was used, although the longest possible signal was used to identify an aircraft in distress.

    IFF was fitted to all RAF combat aircraft, and probably large numbers of transports etc as well. Basically any aircraft that might have a need of it.
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  7. #7
    All sides had an IFF system. We have an original code book, cipher cards, and metal cipher key for our FW190 in the Museum.

    All the best,

    Crumpp
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  8. #8
    UK,USA,Germany,Japan all fielded IFF systems during the war. In typical Japanese efficiency the Navy equipment did not work with the Army system. (hands up all who just KNEW that this would be the case even if you did not already know the fact of the matter!)

    UK (and indeed western allied policy) was to not rely on it exclusively. But instead to demand that visual confirmation be conducted, as the IFF systems of the day could be -

    1. Not turned on by the suspect plane.

    or

    2. Broken (an all to common occurence given the vacuum tube technology).

    The only exception to this rule was if you came upon an unidentified airplane when flying over the continent that was in a landing pattern. In this situation it was safely assumed to be an enemy plane. So even if IFF were in widespread use, by everyone, everywhere - it was largely valueless given the unreliability of the equipment.

    In addition to the liability of the eauipment carrying the equipment introduced yet another potential liability. There is a German axiom that all transmissions are treason. (I think I worded that right - but all this is OTOH). And this axiom was never more true that after the UK developed a piece of equipment called PERFECTOS. The intention behind perfectos was to trip the German IFF (ESTLING - iirc IFF system). So that when PERFECTOS was installed is a Mosquito - you could push a button and then be guided in the general direction of a Luftwaffe night fighter. Again IIRC PERFECTOS gave a direction only, and had a range of ten miles when the Luftwaffe fighter was pointing away, and 50 miles when pointing toward the so equipped Mosquito. Because of this Luftwaffe crew became even more wary of using it for their own purposes.

    Knowing the possibility of it being spoofed, some UK crews would also (for justified and paranoid reasons of self preservation, also switch their sets off.)
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  9. #9
    MB_Avro_UK's Avatar Senior Member
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    Interesting post Bewolf

    We need to know more.

    Best Regards,
    MB_Avro.
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  10. #10
    I believe the British system worked like this.
    The Radar would send a ping. Striking the target aircraft. The target would transmit a ping back to the Radar. The ping was encoded which gave the aircrafts identity. The system was introduced after the infamous Battle of Barking Creek. When a Squadron of Spitfires was scrambled to intercept a friendly returning bomber force. Files relating to the battle have been marked `Never to be released to the Public`. The Squawk code used on todays civil aircaft are very similar.

    Towards the end of the war. Some Lancasters had Automatic Gun Laying Turrets installed at the rear. A radar would scan the back of the aircraft and shoot at any aircraft that was picked up. The system could not tell friend from foe. So all Lancasters had Z aerials (the two aerials on top of the flat glass at the front of the aircraft) fitted to tell the aircraft ahead that it was a friend.
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