Procedings of the National Academy of Science, U S A. 2007 July 24; Volume: 104(30), Pages: 12398-12403.
Published online 2007 July 3. doi: 10.1073/pnas.0702040104. PMCID: PMC1906724 - Copyright © 2007 by The National Academy of Sciences of the USA
The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina
Sankar Chatterjee, Department of Geosciences, Museum of Texas Tech University, Box 43191, Lubbock, TX 79409-3191; R. Jack Templin, retired aeronautical engineer, formerly with the Canadian National Research Council in Ottawa, 2212 Aster Street, Ottawa, ON, Canada K1H 6R6; and Kenneth E. Campbell, Jr., Department of Ornithology, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007
Edited by Steven Vogel, Duke University, Durham, NC, and accepted by the Editorial Board June 6, 2007
Author contributions: S.C. designed research; S.C. performed research; R.J.T. contributed new analytic tools; K.E.C. studied the fossil; S.C. and R.J.T. analyzed data; and S.C., R.J.T., and K.E.C. wrote the paper.
Received March 5, 2007.
ABSTRACT
We calculate the flight performance of the gigantic volant bird Argentavis magnificens from the upper Miocene (~6 million years ago) of Argentina using a computer simulation model. Argentavis was probably too large (mass ~70 kg) to be capable of continuous flapping flight or standing takeoff under its own muscle power. Like extant condors and vultures, Argentavis would have extracted energy from the atmosphere for flight, relying on thermals present on the Argentinean pampas to provide power for soaring, and it probably used slope soaring over the windward slopes of the Andes. It was an excellent glider, with a gliding angle close to 3º and a cruising speed of 67 kph. Argentavis could take off by running downhill, or by launching from a perch to pick up flight speed. Other means of takeoff remain problematic.
You can read the paper here:
The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina
One thing you might notice is that being able to glide (beyond very short distances) but not to fly is no way to live. The first time you ever got caught in any sort of a real wind you’d be carried far from home and you’d have to walk back and hope nothing ate you while you were doing it.