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Science of lightening

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  • 20-09-2006 8:39pm
    #1
    TenLeftFingers
    Registered Users Posts: 683 ✭✭✭


    Myself and my housemates are watching a documentary on BBC1. A police helicopter had to land because there was a forecast of lightening. Some one made the point that since the helicopter isn't grounded, the lightening should be a threat.

    I do know that the blades of a helicopter can have lightening protection so it obviously is an issue, but can anyone enlighten us as to how or why lightening is a threat?

    Cheers!
    merlin


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    #2
    sirpsycho
    Registered Users Posts: 876 ✭✭✭sirpsycho


    Lightning can damage the blades which in turn can cause imbalances which would lead to vibrations in the rotors and eventually lead to a failure in a rotor.


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    #3
    TenLeftFingers
    Registered Users Posts: 683 ✭✭✭TenLeftFingers


    But the argument that my friend here is making is that the helicopter isn't earthed, so the current shouldn't be able to travel - making the helicopter immune?

    Obviously we're incorrect, but I don't understand why :)


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    #4
    Snowbie
    Registered Users Posts: 5,033 ✭✭✭Snowbie


    When a plane was coming into land in the US it was hit by lightning,the lightning travelled around the exterior and to the ground.Like a lightning rod.
    The same could be said about a helo as it is made of an alloy too.
    But havin said that the rotors are metal and could easily conduct it into the engine knocking or frying it out or instrument failure resulting in loss of control.


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    #5
    sirpsycho
    Registered Users Posts: 876 ✭✭✭sirpsycho


    I think it may only happen in the air if the plane happened to be travelling through the air where the lightning occured. Also, with the plane being metal on the exterior then it would facilitate a better path for lightning to pass through than air.


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    #6
    Snowbie
    Registered Users Posts: 5,033 ✭✭✭Snowbie


    Nope,a programme about lightning and conductor rods.Plane was landing (not landed),CG(Fork) lightning hit the aircraft,in turn left the plane unscathe and found its way towards ground.
    Sure planes get hit by lightning when travelling through storms which they cant avoid and causes no harm,its the turbulance which is the problem.

    It was this plane i suppose was the highest point when it was hit by the fork lightning and was documented.


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    #7
    jd
    Registered Users Posts: 5,701 ✭✭✭jd


    As snowbie said, it wouldn't be the lightning so much as the turbulence that is the problem...
    jd


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