Benedict, Tom wrote:
>
> An acquaintance asked me this question today. Can anyone give me a detailed
> explanation of the aerodynamics of birds?

> Tom Benedict
> tbenz at halcyon.com

I design, build, and fly radio control gliders (no motor). I know very
little about aerodynamics. I learned most of what I know from watching
the gulls, Eagles, Ravens and Turkey Vultures. I have flown my gliders
with the gulls in slope lift and thermals (a hot bubble of air that
breaks loose from the ground and rises). Some thermals are so strong
that they can take a glider up and out of sight--never to be seen again.

Rob Conway and Christopher Hill summed it up very nicely. I would only
add that the angle of attack of the airfoil (wing) in relation to the
air moving toward it determines the direction of flight. (up, down,
sideways) When the wing is tipped up too far it will stall, (no more
lift). When it is tipped down to far it will make what ever is attached
to it lose altitude real FAST!
Oh yes, that reminds me of one day this last summer before we started
birding. I was flying my glider (60" wing span) and a young? gull came
along and started to imitate the planes every move. I would turn left
and it would turn left. etc. So I said to myself--self--lets see what
this guy is made of. I put the plane into a slight dive then pulled up
and did a loop. The gull went into a slight dive, then pulled up, and at
the top of the loop started to flip flop and tumble. It guickly
recovered, gave a squak and flew away. I have wondered if the squak was
gull language for "show off".

Today we watched a Raven do a 1/2 snap roll (flying upside down)and then
back to normal flight by reversing the process. I think the Raven does
this by pulling in one wing a split second before the other one. The
wing that is still extended would start the roll, becuase it would be
the only one that was creating lift. Meanwhile the tail feathers are
doing 93,762 different things at the same time to maintain straight and
level flight. WOW!!

Jerry Converse
Grand Coulee, WA