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Re: avian flight




David Marjanovic wrote:

> >   I can't speak for Jim Cunningham, who's aeronautics and
> > mathematics specialty is well above mine.
>
> And mine, and maybe even above Ebel's...

Oh pleease -- I don't know diddly about this stuff.

> >   I strongly disagree. Lift is less than drag in a parachuter,
> > and there is no thrust, thus lift is directly opposed to drag.
> > The animal drops.

I lost track of who said the above, but parachuting is generally defined as a
descent with a glideslope less than 1:1.  Parachutes can and do generate
considerable thrust, and modern paragliders can actually glide with glideslopes
up to about 5 or 6 to 1, perhaps better (I don't keep up much with paragliding).

> Weight pulls the parachuter downwards, and drag pulls it upwards, so drag is
> "lift"... As there is no lift

How do you define the forces when the parachutist is adjusting the chute to
provide a horizontal component so that he's not descendiing straight down?

> OK. That's more or less what I've wanted to describe, only in much detail and
> very slowly... and I'm getting tired, my English is leaving me.

Shucks, you speak it better'n us southern american boys.  Our grammer ain't all
that good even when we'uns don't be tired.

> (We don't have _any_ gliding animals in Europe... :.-( )

Yes, you do.  They hang out at the glider ports.  I'm seen 'em.  Some of the
world's best sailplanes are designed, built, and flown in Europe by some of the
world's best pilots.