[R] OT Sorta: Strouhal Numbers, Unladen Swallows and Monthy Python....

Marc Schwartz MSchwartz at medanalytics.com
Wed Nov 19 20:01:09 CET 2003

Greetings all,

Every now and then, as we engage in serious discourse, it seems
appropriate to throw something into the mix that might digress and
brighten the day.

So, what is a Strouhal Number?

"For an animal or insect in flight, the Strouhal number is determined by
the frequency (f) of wing strokes, multiplied by the amplitude (A) of
the wing, divided by the animal’s forward speed (U) through the air.

The Strouhal number is equal to f A/U"

Jonathan Corum (a graphic designer), has put forth an article on the
graphic representation of birds in flight using Strouhal numbers
(http://www.style.org/strouhalflight/). This is based upon some recently
published research in Nature:

Graham K. Taylor, Robert L. Nudds, Adrian L. R. Thomas
Flying and swimming animals cruise at a Strouhal number tuned for high
power efficiency
Nature 425, 707–711 (October 16, 2003)

Perhaps more importantly, Corum has attempted to address an "age old"
question raised in the famously funny film "Monty Python and the Holy
Grail". The question:

"What is the airspeed velocity of an unladen swallow?"

Hence, the article:

Estimating the Airspeed Velocity of an Unladen Swallow

For those who are Monty Python fans, enjoy...  :-)

Best regards,

Marc Schwartz

Sir Bedevere: How do know so much about swallows? 
King Arthur: Well, you have to know these things when you're a king, you

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