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Re: Pterorhynchus dewlap



I would only add that speed is something of a relative term when it comes to fliers.

Parasite drag (comprised of form drag and skin friction drag) -- parasite drag is what Ken and David seem to be referring to -- increases with the square of the speed, so is indeed relatively unimportant at very low speeds.

However, induced drag (which is a function of aspect ratio and lift coefficient) DEcreases with the square of the speed, so is not too significant at high speeds, but is by far the most significant factor at low speeds.

For non-flapping flight,
Minimum required power will occur when the parasite drag is 1/3 the induced drag.
Maximum range will occur when parasite and induced drag are equal.
The latter means that for maximum range, speed will need to be adjusted over time, as weight is burned off.


And for an animal whose flight is powered by flapping, the streamlining of the wings is more important than that of the torso, neck, and head because the wings are moving faster on average than the rest of the animal.

I wouldn't want anyone to think a low speed flying animal isn't draggy.

All the best,
Jim


----- Original Message ----- From: "david peters" <davidrpeters@earthlink.net>
To: <Ken.Carpenter@dmns.org>; <dinosaur@usc.edu>
Sent: Thursday, February 02, 2006 9:18 AM
Subject: RE: Pterorhynchus dewlap



Agree completely.
David Peters
St. Louis

-----Original Message-----
From: Ken.Carpenter@dmns.org
Sent: Feb 1, 2006 9:32 AM
To: davidrpeters@earthlink.net, dinosaur@usc.edu
Subject: RE: Pterorhynchus dewlap

Streamlining to reduce drag only becomes important at high speed when
drag increases. It is not as important in a low speed swimmer or flier.
Compare the body of a high speed swimmer like a tuna versus the slow
speed, high drag eel. Or falcon in a dive vs prairie chicken.