Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site psivax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!tektronix!hplabs!sdcrdcf!psivax!friesen From: friesen@psivax.UUCP (Stanley Friesen) Newsgroups: net.origins Subject: Re: astronomers, flesh and blood gliders, out-of-context quotes Message-ID: <739@psivax.UUCP> Date: Wed, 18-Sep-85 18:31:46 EDT Article-I.D.: psivax.739 Posted: Wed Sep 18 18:31:46 1985 Date-Received: Mon, 23-Sep-85 00:39:03 EDT References: <395@imsvax.UUCP> Reply-To: friesen@psivax.UUCP (Stanley Friesen) Organization: Pacesetter Systems Inc., Sylmar, CA Lines: 59 Summary: In article <395@imsvax.UUCP> ted@imsvax.UUCP (Ted Holden) writes: > > > There are several kinds of animals on our planet which can > glide, but are not generally capable of flying. These include > the flying squirrel, the flying fish, and one or two kinds of > lizards. In each of these, gliding is basically an escape > mechanism which they use occasionally to get out of harms way, > and which they use to cover small distances, typically 50 or 100 > feet. The flying fish and lizards must jump vigorously to > achieve their shorts glides, while the squirrel takes off from > trees. None of these creatures RELIES on gliding as its primary > mode of transportation and, in that sense, there are no true > gliders amongst the animals of our planet. There are none now, > there have never been any, and there never shall be any. > This is somewhat misleading, there may be no *pure* gliders which rely on gliding for transportation, bu there *are* a number of animals that are *predominantly* gliders. These include the Albatross and many(or even most) Vultures, especially the giant Vultures called Condors. These animals have sufficient musculature in thier wings to wupplement gliding with an occansional flap(to provide that small extra push needed to stay aloft). The wing structure of the larger pterosaurs(such as Quetzalcoatlus and Pteranodon) is very close indeed to that of an Albatross. In short the comparison of these organisms to Flying Squirrels and the like is an apples/oranges comparison. > >>Langston is not describing the same behemoth which flies by >>expending large amounts of power flapping its wings that Ted does. >>For a gliding animal such as Langston postulates, large amounts of >>wing power are not required, as the necessary lift comes from thermals. >>True, getting airborne is not easy, but Langston proposes a plausible >>mechanism, well known from living (though smaller) creatures. Once >>airborne there is no reason why *Quetzalcoatlus* could not have >>remained aloft all day, as unpowered sailplanes do today. > > > Now, we've all seen vultures take off from low ground by simply spreading >their wings and ascending into the rising heat waves coming off the ground, >haven't we? I mean, these guys seem to be describing the Texas pterosaur as a >prehistoric G. Gordon Liddy, with superman cape attached, only the real >G. Gordon Liddy at least had the sense (if you could call it that) to try his >stunt from the roof of his uncles barn. The technique didn't work for Liddy >(who spent several months in the hospital) any better than it would have for >Quetzalcoatlus Northropi, which outweighed Liddy by about 100 lbs. > But it *does* work for the larger Vultures(how many times have yoy even *seen* a Condor, let alone watched one take off?). Mr Liddy didn't have the advantage of fantastically light bones like birds and pterosaurs. Also, he probably was using the wrong wing proportions. This is where the thrice mentioned *low* stall speed calcualated for these animals becomes important, it is what allows this to work. -- Sarima (Stanley Friesen) UUCP: {ttidca|ihnp4|sdcrdcf|quad1|nrcvax|bellcore|logico}!psivax!friesen ARPA: ttidca!psivax!friesen@rand-unix.arpa