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#1




FWD: Argentavis from the Miocene
Hi Gang
This is a tough and pretty rigorous article on the flying characteristics of todays' and yesterdays' large soaring birds with comparisons to modern gliders (ASW21). Worth a read. (Originally posted on the paraglider SFBAPA Group.) Dave http://www.pnas.org/cgi/reprint/104/30/12398 
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#2




FWD: Argentavis from the Miocene
On Feb 13, 9:18 am, "
wrote: Hi Gang This is a tough and pretty rigorous article on the flying characteristics of todays' and yesterdays' large soaring birds with comparisons to modern gliders (ASW21). Worth a read. (Originally posted on the paraglider SFBAPA Group.) Dave http://www.pnas.org/cgi/reprint/104/30/12398 Really interesting article. Thanks for pointing it out. I wonder how they got around in the winter. If the lift in the pampas is like it is here in California in the winter time, they must have done a lot of walking. Larry 
#3




Argentavis from the Miocene
This article claims that this very large extinct condor
(Argentavis magnificens) had a glide ratio of 3% at 67 kph, which is about 33:1. This is better than many older and some newer (e.g. PW5) gliders. So much for evolution! Del Copeland At 17:24 13 February 2008, wrote: Hi Gang This is a tough and pretty rigorous article on the flying characteristics of todays' and yesterdays' large soaring birds with comparisons to modern gliders (ASW21). Worth a read. (Originally posted on the paraglider SFBAPA Group.) Dave http://www.pnas.org/cgi/reprint/104/30/12398 
#4




Argentavis from the Miocene
Del C wrote:
This article claims that this very large extinct condor (Argentavis magnificens) had a glide ratio of 3% at 67 kph, which is about 33:1. This is better than many older and some newer (e.g. PW5) gliders. So much for evolution! A 3 degree glide angle is a slightly over 19:1 glide ratio. This is high school trigonometry  simply look up the cotangent of 3 (the value of y/x). Not quite as good as a 233 :). Tony V. 
#5




Argentavis from the Miocene
A 3 degree glide angle is a slightly over 19:1 glide ratio. This is high school trigonometry  simply look up the cotangent of 3 (the value of y/x). Not quite as good as a 233 :). Yeah, I know, cot = adjacent/opposite  x/y. I hate typos :). Tony 
#6




Argentavis from the Miocene
The article claimed a glide angle of 3 PERCENT, which
is 3 in 100 or approximately 33:1. 3 DEGREES is roughly 3 in 60 or about 20:1, as you say. I did rather wonder if the article got percent and degrees mixed up, as I understand that the best modern soaring birds do not have an L/D of much over 20:1. Del Copeland At 15:06 17 February 2008, Tony Verhulst wrote: Del C wrote: This article claims that this very large extinct condor (Argentavis magnificens) had a glide ratio of 3% at 67 kph, which is about 33:1. This is better than many older and some newer (e.g. PW5) gliders. So much for evolution! A 3 degree glide angle is a slightly over 19:1 glide ratio. This is high school trigonometry  simply look up the cotangent of 3 (the value of y/x). Not quite as good as a 233 :). Tony V. 
#7




Argentavis from the Miocene
Sorry, my mistake this time. I speed read and for some
reason took in the birds glide angle as being 3% rather than 3 degrees. Unfortunately this conclusion was compounded by a very mathematically gifted friend of mine, who is a professional physicist, writing to me on this subject when he had also made the same mistake! Del Copeland At 15:36 17 February 2008, Del C wrote: The article claimed a glide angle of 3 PERCENT, which is 3 in 100 or approximately 33:1. 3 DEGREES is roughly 3 in 60 or about 20:1, as you say. I did rather wonder if the article got percent and degrees mixed up, as I understand that the best modern soaring birds do not have an L/D of much over 20:1. Del Copeland At 15:06 17 February 2008, Tony Verhulst wrote: Del C wrote: This article claims that this very large extinct condor (Argentavis magnificens) had a glide ratio of 3% at 67 kph, which is about 33:1. This is better than many older and some newer (e.g. PW5) gliders. So much for evolution! A 3 degree glide angle is a slightly over 19:1 glide ratio. This is high school trigonometry  simply look up the cotangent of 3 (the value of y/x). Not quite as good as a 233 :). Tony V. 
#8




Argentavis from the Miocene
Del C wrote:
Sorry, my mistake this time. I speed read and for some reason took in the birds glide angle as being 3% rather than 3 degrees. Well then, we're all missreading:). I read the article several days ago and remember reading 3 degrees. So when I saw your 3, I never saw the percent symbol and just assumed degrees. Getting old, I guess. LOL Tony 
#9




Argentavis from the Miocene
Tony Verhulst wrote:
A 3 degree glide angle is a slightly over 19:1 glide ratio. This is high school trigonometry  simply look up the cotangent of 3 (the value of y/x). Not quite as good as a 233 :). Yeah, I know, cot = adjacent/opposite  x/y. I hate typos :). Not all calculators have cotan (my computer's desktop calculator doesn't, nor does my HP28S), but 1/tan(x) gives the same answer. If the angle is less than approximately 4.5 degrees it doesn't much matter whether you use tan or sin  for a 3 degree glide slope the difference is tiny: 1:19.081 vs. 1:19.107  an error of just over 0.1%.  [email protected]  Martin Gregorie gregorie.  Essex, UK org  
#10




Argentavis from the Miocene
Not all calculators have cotan (my computer's desktop calculator doesn't, nor does my HP28S), but 1/tan(x) gives the same answer. Ah, true, but there's this thing called the World Wide Web :) http://tinyurl.com/22r8kw Tony V. 

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