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Re: Everyone's discussing bird origins...



At 02:35 PM 9/27/96 -0500, Mickey opened a can of... well... on my last post:

>I'd actually argue that *most* animals are dynamically unstable.

        TOUCHE'!  You are quite right, IMH(and getting "H"er)O.  If birds
were actually unstable in flight, that would clinch it, but we're only
arguing ground animals, and, having done some wacky things in a run myself,
I can see it wouldn't be that hard. 

>e.g. falling) are probably pretty rare in animals.  Soaring birds and
>cruising fish are about the only examples I can think of.

        Birds in a dive (short lived example...).
        Have you ever sailed?  Sailing, which sounds analogous enough to
gliding, requires *constant* feedback to keep the boat properly oriented to
get the maximum force of the wind.  it is a *very* unstable condition.
First time I went sailing, I was really afraid to hold the boat in that
position, because it _was_ so unstable (and at a 30 degree angle to the
horizontal.  It always looks to me like birds seem to be constatly tweaking
their aerodynamic surfaces to keep efficieny high while soaring.
        How do fish "cruise"?

>1) chase a bird (especially a bird that lives among humans --
>like a rock dove (i.e. "pigeon")) by walking towards it slowly and

        I can see the analogy well enough without scaring more of the locals
around here...  :)

> 2) Find yourself a big preying mantis, get it to fly, and
[snip]
>successful maneuvers under this circumstance is to flare out its wing
>covers and curl up its abdomen in order to reduce lift and increase
>drag at the same time.[snip]

        Mother of...  Wow!

>Fighter pilots have been impressed by these sorts of maneuvers since they do
>similar things in a knife fight.

        Well, they do now...  I recall that recovery from such manuevers is
a major goal of current aerodynamic research, qv X-31.

        Wagner
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