Forget not the Physics, Friam Friends!

[plissaman]

 

It is fun to read Friamers’ hypotheses on formation flight in birds.  They are entirely unprejudiced by any knowledge of the topic. Although knowledge of a subject is counter-friamistic and takes hard work, I modestly suggest that it is helpful to understand some of the aerodynamic principles behind formation flight before hyperventilating too much.    The fact is that the Biot-Savart Law teaches that the asymptotic state is really quite close, as characteristic of a semi-infinite dipole field.  Consequently, aerodynamics shows that for favorable interaction flyers can utilize uneven Vees, branched Vees, small Vees, big Vees, broken Vees – and migrating birds use them all. Or look as though they do!  The tip station is theoretically the most unfavorable, but better than being solo.  I have published seven papers on avian flight, and read and reviewed a good few more, so don’t know very much, but I would not presume any hypothesis on really why they do it, and who does what to whom. That’s for the birds!

Peter Lissaman, Da Vinci Ventures

Expertise is not knowing everything, but knowing what to look for.

1454 Miracerros Loop South, Santa Fe, New Mexico 87505,USA
tel:[phone]

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[Hugh Trenchard]



Thank you for your illuminating observations of Friam discussions, as well as illuminations of your own depth of knowledge.  Of course this is why people engage in such informal discussions as these: to learn and share ideas. Insults and denigrations do not come unexpectedly, as I am frankly unsure if there is any other way to interpret some of your comments (but please correct me I'm wrong!), and it certainly takes a certain magnitude of courage to expose one's ignorance in the face of these expectations. 

 

Now, we've all seen the various Vee formations.  I had queried about in-flight rotational dynamics -- do your papers discuss these dynamics, or do you think I am mistaken that these rotational dynamics actually occur?  Assuming they occur, it seems to me they have not been much studied, though I would love to be pointed to references.  I have seen the Andersson and Wallander paper "Kin selection and reciprocity in flight formation?" 2004 Behavioral Ecology, Vol. 15 No. 1 (which cites one of your 1970 papers),  which proposes a kin selection model for certain dynamics, which I hypothesize (yes "hypothesize") are better explained by an energy dissipation model. 

 

Certainly understanding the aerodynamic principles are important as the basis for these dynamics. But these underlying principles do not change the fact that birds and living organisms fatigue at different rates and have finite energy supplies, and if one is looking at a model for in-flight rotational dynamics, I boldy suggest that once we have a general understanding of the aerodynamical principles, the technical aerodynamics are secondary to bird fatigue rates in the various positions within the flight formation. 

 

Why would you simply dismiss the possibility of developing a model which describes certain observable collective behaviours - particularly when it is an energy dissipation model, as I like to explore, which is highly amenable to classical physics?   

 

Hugh

 

"Modesty is not presuming others know nothing."

 

----- Original Message -----

From: [hidden email]

To: [hidden email]

Sent: Tuesday, March 08, 2011 12:20 PM

Subject: [FRIAM] Forget not the Physics, Friam Friends!

 

It is fun to read Friamers’ hypotheses on formation flight in birds.  They are entirely unprejudiced by any knowledge of the topic. Although knowledge of a subject is counter-friamistic and takes hard work, I modestly suggest that it is helpful to understand some of the aerodynamic principles behind formation flight before hyperventilating too much.    The fact is that the Biot-Savart Law teaches that the asymptotic state is really quite close, as characteristic of a semi-infinite dipole field.  Consequently, aerodynamics shows that for favorable interaction flyers can utilize uneven Vees, branched Vees, small Vees, big Vees, broken Vees – and migrating birds use them all. Or look as though they do!  The tip station is theoretically the most unfavorable, but better than being solo.  I have published seven papers on avian flight, and read and reviewed a good few more, so don’t know very much, but I would not presume any hypothesis on really why they do it, and who does what to whom. That’s for the birds!

Peter Lissaman, Da Vinci Ventures

Expertise is not knowing everything, but knowing what to look for.

1454 Miracerros Loop South, Santa Fe, New Mexico 87505,USA
tel:[phone]

---

============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org

============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org