FWD: 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

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.

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

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 |

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.

Tony Verhulst wrote:

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 :-)

I think I may have heard of that somewhere, but its nice to have these
things on the desktop.

I just checked the old standby command line calculators. No joy there
either. However, all is not lost - my spreadsheet has the lot. I'm using
Open Office, but Excel probably has them all too.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |