Re: [wingstroke]

["Tim Williams" <twilliams_alpha@hotmail.com>]

David Marjanovic wrote:

> > They need thrust to stop them from descending.  A glider can generate an
> > airfoil to give it lift, but it can't stay in the air forever.  For that 
> you need the flight stroke.
>
> Same as above -- why do none do it today?

Birds and bats do it.  The airfoil provided by the wing gives them lift. The 
flight stroke imparts a force to a fluid medium (air in this case), 
generating thrust which is what keeps birds and bats in the air.


> Some modern gliders can glide over 100 m. This is close enough >to "staying 
> in the air forever" for all practical purposes, I'd say.

I wouldn't say that at all.  I hope the next time I catch a flight from Los 
Angeles to Sydney the plane doesn't return to the runway after travelling 
only 100m.  I will be very skeptical when the Captain assures me, "Sir, it's 
close enough to staying in the air for 14 hours, for all practical 
purposes."


Tim

------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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