1. #1
    SkyChimp's Avatar Senior Member
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    Regards,
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  2. #2
    SkyChimp's Avatar Senior Member
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    Regards,
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  3. #3
    Where did you find it? I've seen this before, but can't remember the source. It's hard to believe it was done with standard exposures on black-and-white film, reworked in the darkroom...not 'photoshopped.' These guys were good.

    I'm lucky enough to have received from an uncle all of the National Geographic magazines from 1940 to 1945. The war photos are hard to believe, they're so sharp.


    There is no 'way' of winning;
    There is only Winning!
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  4. #4
    What happens if we won't rise up to meet it?

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  5. #5
    necrobaron's Avatar Senior Member
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    Can someone explain to me exactly what I'm looking at? I've never seen this "spiral" effect.

    "Not all who wander are lost."
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  6. #6
    It is just contrails from the propellor blade.

    Same phenomena as trails from wingtips. Common with helicopters too, mostly seen in a naval setting (humidity).

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  7. #7
    necrobaron's Avatar Senior Member
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    Ah,I see.

    Is this a common occurence? What causes it?

    "Not all who wander are lost."
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  8. #8
    The low pressure air coming from the blade tip can hold less water than surrounding high pressure air, so the water in that air condenses into a visible vapor.

    Same with aircraft wing, which has lower pressure on top that on bottom. At high AOA, the pressure on top decreases, and water in that air condenses.

    The higher the humidity, the longer it takes for this water vapor to be re-absorbed in the surrounding air. Since the air over the sea is almost always at saturation, the trails will stay longer.

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  9. #9
    LEXX_Luthor's Avatar Senior Member
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    Somebody posted a P~38 pilot memoir and there was told of P~40s used in training. The accepted correct turn to final was judged by wingtip contrails and the dude on the ground would tell P~40 pilots that were not pulling hard enough to make contrails that they have to turn harder. On dry days this resulted in P~40s stalling into the ground. They had to change that method of judgement.
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  10. #10
    heywooood's Avatar Senior Member
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    Thats a great effect - I've only seen it one other time, quite recently in fact.

    Opening night in Dodger stadium.. caused by Phil Nevins bat when he hit that Grand Salami !! Padres win! Padres Win!!!
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