A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

FWD: Argentavis from the Miocene



 
 
Thread Tools Display Modes
  #1  
Old February 13th 08, 06:18 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 29
Default 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
  #2  
Old February 16th 08, 04:53 AM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 11
Default 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  
Old February 17th 08, 09:46 AM posted to rec.aviation.soaring
Del C
external usenet poster
 
Posts: 35
Default 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  
Old February 17th 08, 04:05 PM posted to rec.aviation.soaring
Tony Verhulst
external usenet poster
 
Posts: 193
Default 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 2-33 :-).

Tony V.
  #5  
Old February 17th 08, 04:13 PM posted to rec.aviation.soaring
Tony Verhulst
external usenet poster
 
Posts: 193
Default 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 2-33 :-).



Yeah, I know, cot = adjacent/opposite - x/y. I hate typos :-).

Tony
  #6  
Old February 17th 08, 04:31 PM posted to rec.aviation.soaring
Del C
external usenet poster
 
Posts: 35
Default 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 2-33 :-).

Tony V.




  #7  
Old February 17th 08, 04:59 PM posted to rec.aviation.soaring
Del C
external usenet poster
 
Posts: 35
Default 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 2-33 :-).

Tony V.








  #8  
Old February 17th 08, 06:11 PM posted to rec.aviation.soaring
Tony Verhulst
external usenet poster
 
Posts: 193
Default 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 miss-reading:-). 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  
Old February 17th 08, 11:41 PM posted to rec.aviation.soaring
Martin Gregorie[_1_]
external usenet poster
 
Posts: 276
Default 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 2-33 :-).



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 HP-28S), 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%.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
  #10  
Old February 18th 08, 03:29 AM posted to rec.aviation.soaring
Tony Verhulst
external usenet poster
 
Posts: 193
Default Argentavis from the Miocene


Not all calculators have cotan (my computer's desktop calculator
doesn't, nor does my HP-28S), 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.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 02:27 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.