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Re: Quetzalcoatlus could not jump into the air



So this is like the famous Sikorsky quote about bumblebees?

³According to the laws of aerodynamics, the bumblebee can¹t fly, but the
bumblebee doesn¹t know anything about the laws of aerodynamics, so it goes
ahead and flies anyway.²


On 11/8/12 10:53 AM, "Ben Creisler" <bcreisler@gmail.com> wrote:

> From: Ben Creisler
> bcreisler@gmail.com
> 
> 
> A talk at the GSA meeting and a new story:
> 
> 
> https://gsa.confex.com/gsa/2012AM/finalprogram/abstract_205827.htm
> 
> FLIGHT-INITIATING QUADRUPEDAL JUMPS IN THE GIANT PTERODACTYLOID
> QUETZALCOATLUS: FACT OR FANTASY?
> CHATTERJEE, Sankar, Geosciences, Texas Tech University, 3301 4th
> Street, Lubbock, TX 79409-3191, ALEXANDER, David E., Ecology &
> Evolutionary Biology, University of Kansas, 2041 Haworth Hall, 1200
> Sunnyside Avenue, Lawrence, KS 66045, and TEMPLIN, R. Jack, 2212 Aster
> Street, Ottawa, ON K1H 6R6, Canada, jtemplin@rogers.ca
> Large pterosaurs could takeoff from an elevated perch by diving into
> the air to initiate flight, but to take off from level ground was
> arduous. Our estimated mass of the giant Quetzalcoatlas from the Late
> Cretaceous Big Bend National Park of Texas is about 70 kg, which is
> close to the theoretical upper mass limit for a flying animal.
> Quetzalcoatlus could run bipedally downhill to pick up flying speed, a
> technique used by albatrosses and hang glider pilots. It has been
> proposed recently that Quetzalcoatlus with a new calibrated mass of
> 250 kg was capable of initiating flight directly from the ground using
> forelimbs as a catapult similar to the style of common vampire bat (~
> 25 g). One issue is scaling. What is possible for a lightweight bat
> appears impossible for a 10,000 times heavier pterodactyloid, which,
> due to surface-to-volume ratios, will have approximately 0.01 times
> the muscle force per unit mass of the bat. Another is the height
> achieved by such a ³pole-vault:² the maximum ballistic jump height of
> 2 to 3 meters would not be high enough to allow a significant
> downstroke, where most lift and thrust is produced. With a wingspan of
> 10.4 m, Quetzalcoatlus would not have been able to flap vigorously for
> lift generation from such a jump without smashing its delicate wings
> on the ground. Moreover, the animal would need about 2440 watts to fly
> level after jumping; the estimated maximum mechanical power available,
> however, even with a few seconds of maximal anaerobic muscle
> contraction, was approximately 1600 W, far below the flying speed that
> would result in crash landing. Indeed, the body mass of 250 kg itself
> appears to be largely overestimated, as powered flight and ground
> takeoff seem unlikely for an animal that heavy.
> 
> 2012 GSA Annual Meeting in Charlotte
> 
> ====
> 
> news story:
> 
> http://news.discovery.com/animals/flying-dinosaur-pterodactyl-121108.html