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Re: Fw: Campbell's even crazier than a MANIAC? (archeopteryx climbing)

Technically you can soar with only a gradient in the airmass velocity.
Albatross do not use "updrafts", they make use of the differential in wind 
velocity near the surface, vs say 20 feet high, and extract energy by 
traversing from between the altitudes.
Likewise,one can dive in strong sink, and when transitioning the barrier from 
extreme sink to weak sink, energy will be extracted from the gradient- when you 
enter the weak sink, your airspeed will jump way up.
Of course the faster the average rate the air is sinking, the larger that 
gradient must be to actually climb relative to the ground. It is quite possible 
to be climbing relative to the airmass, and still sinking.
Likewise in a large mass of lifting air - one can cross zero gradients, and 
still go up relative to the ground, but they are continuosly sinking relative 
to the airmass. Of course the aircraft/creature must be sufficiently efficient 
as well to make use of a gradient or lifting air.

--- On Tue, 9/30/08, jrc <jrccea@bellsouth.net> wrote:

> From: jrc <jrccea@bellsouth.net>
> Subject: Fw: Campbell's even crazier than a MANIAC? (archeopteryx climbing)
> To: dinosaur@usc.edu
> Date: Tuesday, September 30, 2008, 8:17 AM
> Soaring does not require an updraft.  In fact, it is
> possible to soar in
>  continuous sink, so long as that sink is variable and the
> soarer doesn't
>  mind pulling substantial and sudden negative g's from
> time to time. (that
>  said, I don't know of any vertebrates that soar in
> continuous sink).  It is
>  also possible to soar using horizontal shears, and that is
> done quite 
> often.
> JimC
> >
> > ----- Original Message ----- 
> > From: "Dann Pigdon"
> <dannj@alphalink.com.au>
> > To: <dinosaur@usc.edu>
> > Sent: Sunday, September 28, 2008 7:21 PM
> > Subject: Re: Campbell's even crazier than a
> MANIAC? (archeopteryx 
> > climbing)
> >
> >
> >> > Soaring requires an updraft,
> >