Re: One Number Describes Animal Flight...

["James R. Cunningham" <jrccea@bellsouth.net>]

I think pretty well all engineers who work much with fluid mechanics
have been aware of the significance of the Strouhal number (and what it
signifies) for some decades now. :-)

Note that among many other things, the Strouhal number doesn't describe
the specific kinematics of the  wingbeat as it varies spanwise.  It's
only a piece of the issue.  Sort of like saying that the sound of all
symphonies is described by the rotation speed of the LP record on which
they were recorded  -- so that by listening to one symphony on one
recording, one has heard them all....  One can design a wingbeat having
a Strouhal number in the range of 0.2 to 0.4 that won't work at all. 
But it is true that most effective wingbeats will be within that range. 
No new news in the announcement (I look forward to reading the paper
though; the fun is in the details).
JimC

Richard W Travsky wrote:
> 
> One number explains animal flight
> Engineers and evolutionists take note: wings and tails beat to the same
> drum.

> A quantity called the Strouhal number measures how efficiently an animal 
> cruises.