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Re: New bird /pterosaur flight paper in PLoS ONE



What on earth do wind conditions have to do with soaring? Some of the best soaring comes on days that are essentially windless. And some comes on days that are quite windy. What you need is atmospheric turbulence and/or thermal lift, and/or lift due to shears, and/or microlift, not wind per se.
Note that sailplanes with wingspans, wing areas, aspect ratios, and gross weights similar to those of the largest pterosaurs are repeatedly capable of soaring non-stop for hundreds of kilometers on an average day, and they don't have the ability to flap at all.
JimC


----- Original Message ----- From: "Andy Farke" <andyfarke@hotmail.com>
To: <dinosaur@usc.edu>
Sent: Wednesday, April 29, 2009 2:33 PM
Subject: New bird /pterosaur flight paper in PLoS ONE




Sato K, Sakamoto KQ, Watanuki Y, Takahashi A, Katsumata N, et al. (2009) Scaling of Soaring Seabirds and Implications for Flight Abilities of Giant Pterosaurs. PLoS ONE 4(4): e5400. doi:10.1371/journal.pone.0005400

Abstract:
The flight ability of animals is restricted by the scaling effects
imposed by physical and physiological factors. In comparisons of the
power available from muscle and the mechanical power required to fly,
it is predicted that the margin between the powers should decrease with
body size and that flying animals have a maximum body size........
These scaling relationships predicted that the maximum limits on the
body size of soaring animals are a body mass of 41 kg and a wingspan of
5.1 m. Albatross-like animals larger than the limit will not be able to
flap fast enough to stay aloft under unfavourable wind conditions. Our
result therefore casts doubt on the flying ability of large, extinct
pterosaurs. The largest extant soarer, the wandering albatross, weighs
about 12 kg, which might be a pragmatic limit to maintain a safety
margin for sustainable flight and to survive in a variable environment.

Available for free download at:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005400

Andy

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