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Re: More on Argentavis



>>Guy, Interesting news. I'm curious as to how the
>>researchers determined that A. couldn't, or would have
>>had trouble flying-- perhaps I'm remembering this
>>incorrectly or incompletely, but wasn't there an
>>aeronautics engineer who stated many years ago that
>>according to the laws of flight dynamics, a bumblebee
>>should in theory be incapable of flight?

As has already been pointed out, this calculation used the incorrect
aeronautical model. Basically, as an organism becomes smaller, the
more 'viscous' the surrounding atmosphere is in relation to it, so
the dynamics of generating lift become different (it is not entirely
incorrect to say it becomes more like swimming than flying). This is
also why insects have flat wings rather than aerofoils. In
exceedingly small insects such as thrips and fairy wasps, even the
flat plane becomes inappropriate, and instead the wing is a number of
plumes coming from a solid base (see
http://www.ucmp.berkeley.edu/arthropoda/uniramia/thysanoptera.html
for an image). And bacteria can just float in the air without any
sort of lift-generating structures at all.

    Cheers,

        Christopher Taylor