Airspeed Velocity Of An Unladen Swallow

An anonymous reader writes "Finally, the question is answered: What is the airspeed velocity of an unladen swallow? A designer with too much time on his hands uses his new method for graphically representing Strouhal numbers to clarify a truly pressing question for all armchair zoologists (and a few Monty Python fans)."

Comments

Ignobel awards

[Space cowboy]

... looks like someone's pushing for recognition :-)

Simon

Capital of Assyria

[Phroggy]

Might as well go completely off-topic on a story like this.

The bonus question was, what's the capital of Assyria? One of the answers was Nineveh, which in the Bible is where God sent Jonah to warn the city's inhabitants of their impending destruction unless they repented of their evil ways. Jonah, who hated the Assyrians and didn't want Nineveh to have a chance to escape destruction, fled to Spain instead (about as far away as he could get), hoping God wouldn't be able to find him there. That obviously didn't work; Jonah was swallowed by a giant fish in the middle of the Mediterranean, then spit out whole; after sulking for awhile he did make the trip to Nineveh, told the people they were being wicked in the eyes of God, and to his dismay, they repented and changed their ways.

So my question to any Slashdotters who happen to be history geeks: is there a non-Biblical historical record of any such change in the attitude or behavior of the people of Nineveh ( or the Assyrian Empire in general) that would coincide with the story about a warning of doom from an Israeli prophet? Biblical stories are always so much more interesting in proper historical context, and I know nothing about the subject, and this isn't an appropriate place to ask, but what the hell, I've got more karma than I know what to do with anyway. :-)

Air-speed velocity?

[technomom]

The thing that always bugged me about this scene in the movie is the term, "air-speed velocity". Isn't that kind of redundant?

Then again, I'm the kind who yells at the Scarecrow in the Wizard of Oz whenever he tells us
"The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side."

JoAnn

Re:Air-speed velocity?

[richmaine]

The "airspeed velocity" also struck me, but no it isn't redundant. It is contradictory. Speed and velocity are different things. (Speed is a scalar,
velocity a vector).

But can we explain the variations?

[G4from128k]

The parent post does a great job of explaining why the Strouhal Number is the same across a range of organisms that use flapping for propulsion. Yet a glance at the graph shows considerable variation among creatures -- a 3:1 range between leaf-nosed bats and gulls. Most of the soaring air-based animals have Strouhal's of around 0.2, whereas the water-based animals have Strouhal's of around 0.3.

It would be interesting to understand not why Strouhal Numbers are constant, but why they vary. I would assume that wing (or fin) shape would affect the optimal Strouhal Number because the Number is calculated on the wing tip, whereas the optimal flap is based on integrating over the wing surface. Wings of different designs, articulations, and flap movement trajectories would have different ratios between the tip-amplitude and the average area-weighted amplitude across the wing surface. I would expect that area-weighted Strouhals to have even less variation across animals that the tip-based number.

Other factors might explain remaining variation. For example, sinusoidal wing beats would have a different Strouhals than square-wave wing beats. Perhaps the Reynolds number might affect Strouhals - explaining the difference between "flight " in air vs. water. Finally, some animals that only fly short distances may have sub-optimal Strouhals because the wings are optimized for other purposes such as courtship.