Re: [FRIAM] frigatebirds - short video
http://ibc.hbw.com/ibc/phtml/votacio.phtml?idVideo=3621tipus=1 Here is a link to a short video which provides a small inkling of the drafting behaviour or frigatebirds. It isn't a long enough video to know if the alignment there was more than accidental, nor does it show more than two in alignment, but it's a start. Thanks for the suggestion about contacting bird-watchers in frigatebird territory for a work-around, I'll look into it. Hugh - Original Message - From: Phil Henshaw [EMAIL PROTECTED] To: 'The Friday Morning Applied Complexity Coffee Group' friam@redfish.com Sent: Saturday, January 06, 2007 9:28 PM Subject: Re: [FRIAM] observations of complex phenomena while in Mexico I'll be glad to see what further patterns you find. Just to clarify, my suggestion was not just that the two colonies were different, but that the variation in local colony behavior might be as great as the variation in local environments where colonies are found. If you were to make observations randomly across the range of the species you'd get a better sense of what behaviors are universal and what are local. What you'd want is a work-around, of course, that would be a little less work. Perhaps you could try getting a list of bird watchers in the frigatebird range and randomly calling them to see what they have to say. As to the generality of a drafting principle, there is at least one major example of it I've given a good bit of study, the formation and evolution of air currents. If you want an example of the vast creativity of local physical processes you might do well to give them a little look. Do all the modeling you like and none of it will produce the degree of intricate and inventive complexity you find in the pathway negotiations taking place around any even mildly warm body like, for example, the one sitting in front of your computer screen right now! Phil Henshaw .·´ ¯ `·. ~~~ 680 Ft. Washington Ave NY NY 10040 tel: 212-795-4844 e-mail: [EMAIL PROTECTED] explorations: www.synapse9.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Hugh Trenchard Sent: Saturday, January 06, 2007 7:16 PM To: The Friday Morning Applied Complexity Coffee Group Subject: Re: [FRIAM] observations of complex phenomena while in Mexico Thanks for all your comments. Next time I'm in Mexico, I will definitely do my best to get some video footage. My recollection of what I saw in October 2005 in Mazatlan is that the various yaws and compensations were easy to see, as you say. I can't remember how long the formations were stable - perhaps generally less than a minute, before the formation would break down (but I'm really just guessing) - but they were long enough to see the dynamics involved. And after the formations broke down, they would often reform again fairly soon. Regarding Phil's comment that the Mazatlan colonies were possibly just different from the Cancun colonies I will need to investigate that. (Frank - I was in Cancun over Christmas, by the way and the migration habits might be a factor involved in when and why they engage in vee formation - something else to investigate). It seems, though, it is unlikely that a single colony in Mazatlan would have developed the vee formation capacity completely independently of a colony in Cancun, especially when the distance between them is not really that great when we think in terms of bird migratory habits. So far, I still think the wind conditions are more likely what prevented vee formation in Cancun, but of course I will need a bit more evidence to support that. Also, Phil, I would argue that strong leadership is not a factor in vee formations. As we all know, self-organized phenomena arise without leaders to guide the emergent patterns - I can't think of why it would be any different for frigatebirds. The formations must self-organize from some principle of interaction - in the case of organisms that save energy by drafting, it is the coupling between them that occurs because there is a physiological or energetic advantage to their coupling (ie. to their drafting). It could be that frigatebird vee formations are simply derived from their inherent natural behaviours and have no basis in any underlying physical principles, but given the advantages conferred upon other types of organisms that engage in drafting dynamics and formations, it seems reasonable to ask if there is there is a physical principle underlying the formations. Nonetheless, what this all suggests to me that it is an area ripe for further study, and that very little work has been done to establish the universality of the drafting principle as I am calling it. I actually think it applies in a lot of other situations as well, from trail formation to aspects of economics, but that's
[FRIAM] Poetry in motion
The procedure is correct But a heluva mess, The Birdies Just Do it, And They could care less Adapted from Lissaman, 2007. By the way, I struggled for many minutes with Interestingly, for a linear Vee, the wing at the apex of the Vee has the maximum saving. In 1971 I was in communication with ornithologists in Florida, who noted that their observations validated our Vee estimates and indicated that the apex position was usually taken by the older and more powerful birds. I assume that the wing at the apex of the the V refers to the lead bird. Absent forward causality, this bird is the one that is flying in virgin air, no So this passage would imply that everybody else is flying with more or less of a disability. In which case, would it be better to fly alone? somebody straighten me out,here. nick [Original Message] From: [EMAIL PROTECTED] To: friam@redfish.com Date: 1/7/2007 12:00:16 PM Subject: Friam Digest, Vol 43, Issue 9 Send Friam mailing list submissions to friam@redfish.com To subscribe or unsubscribe via the World Wide Web, visit http://redfish.com/mailman/listinfo/friam_redfish.com or, via email, send a message with subject or body 'help' to [EMAIL PROTECTED] You can reach the person managing the list at [EMAIL PROTECTED] When replying, please edit your Subject line so it is more specific than Re: Contents of Friam digest... Today's Topics: 1. Re: observations of complex phenomena while in Mexico (Phil Henshaw) 2. Re: Friam Digest, Vol 43, Issue 6 Formation Flight (Peter Lissaman) 3. Re: Friam Digest, Vol 43, Issue 6 Formation Flight (Hugh Trenchard) -- Message: 1 Date: Sun, 07 Jan 2007 00:28:25 -0500 From: Phil Henshaw [EMAIL PROTECTED] Subject: Re: [FRIAM] observations of complex phenomena while in Mexico To: 'The Friday Morning Applied Complexity Coffee Group' friam@redfish.com Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=iso-8859-1 I'll be glad to see what further patterns you find. Just to clarify, my suggestion was not just that the two colonies were different, but that the variation in local colony behavior might be as great as the variation in local environments where colonies are found. If you were to make observations randomly across the range of the species you'd get a better sense of what behaviors are universal and what are local. What you'd want is a work-around, of course, that would be a little less work. Perhaps you could try getting a list of bird watchers in the frigatebird range and randomly calling them to see what they have to say. As to the generality of a drafting principle, there is at least one major example of it I've given a good bit of study, the formation and evolution of air currents. If you want an example of the vast creativity of local physical processes you might do well to give them a little look. Do all the modeling you like and none of it will produce the degree of intricate and inventive complexity you find in the pathway negotiations taking place around any even mildly warm body like, for example, the one sitting in front of your computer screen right now! Phil Henshaw .?? ? `?. ~~~ 680 Ft. Washington Ave NY NY 10040 tel: 212-795-4844 e-mail: [EMAIL PROTECTED] explorations: www.synapse9.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Hugh Trenchard Sent: Saturday, January 06, 2007 7:16 PM To: The Friday Morning Applied Complexity Coffee Group Subject: Re: [FRIAM] observations of complex phenomena while in Mexico Thanks for all your comments. Next time I'm in Mexico, I will definitely do my best to get some video footage. My recollection of what I saw in October 2005 in Mazatlan is that the various yaws and compensations were easy to see, as you say. I can't remember how long the formations were stable - perhaps generally less than a minute, before the formation would break down (but I'm really just guessing) - but they were long enough to see the dynamics involved. And after the formations broke down, they would often reform again fairly soon. Regarding Phil's comment that the Mazatlan colonies were possibly just different from the Cancun colonies I will need to investigate that. (Frank - I was in Cancun over Christmas, by the way and the migration habits might be a factor involved in when and why they engage in vee formation - something else to investigate). It seems, though, it is unlikely that a single colony in Mazatlan would have developed the vee formation capacity completely independently of a colony in
[FRIAM] [OT] Snow Thrower
At the last FRIAM, several folks mentioned wanting to know which snow thrower we bought. Here's the critter: http://www.amazon.com/gp/product/B5OQMG/102-9266426-1206509 .. and yes, the 1 day delivery worked fine (we have Amazon Prime but I think you can always pay for the 1 day delivery and its worth it if you're covered with snow!) We've cleared two very large/long gravel driveways with success, and even though they say it shouldn't be used on gravel, it worked fine. It is very basic: not self propelled or 2-stage design. But we really wanted to avoid the alternative: a heavy, touchy gas system. This is quite light (easily picked up by its handle just beside the chute) which is very nice when getting into tight spaces. It threw the snow far enough in every case we encountered. We were surprised it could handle the large (2 feet) snow fall, even though its designed for much lighter use. Its the little engine that could sort of thing. Not perfect, but small, light and doesn't have all the drawbacks of gas. Epinions has several reviews as well. -- Owen Owen Densmore http://backspaces.net 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] TEDTalks (audio, video)
A friend passed this on: http://www.ted.com/tedtalks/ looks pretty broad and interesting. -- Owen Owen Densmore http://backspaces.net 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] Mechanics of Formation Flight
MECHANICS OF FORMATION FLIGHT -- PETER LISSAMAN Here are some actual facts, which folks may wish to use for discussion on tother hand maybe they just prefer their own opinions! Doesn't matter to anyone who just wants to ramble on a fascinating subject. I am designing flight systems to use turbulent energy, in test flight right now, so, unfortunately, gotta stick to Newtons Laws!. 1. A lifting wing develops one half its induced wash AHEAD of it. Yeah, folks, before the air has even met the wing. Its a continuous fluid, remember! The balance of the induced wash due to the trailing system develops downstream of the wing and is reaches its asymptotic value about 3 spans downstream. Within the span of the wing this induced flow is downwash, more or less spanwise uniform; outboard it is upwards, very intense just beyond the tip and attenuating rapidly as one moves away from the wing. 2. If another wing system is positioned outboard of the wing, it experiences a strong upwash, that will greatly reduce its power requirements. This effect is mutual, and its integrated intensity depends only on the tip separation as a fraction of span. 3. Consider three identical wings, line abreast, call them Left (L) Center (C) and Right (R). In this configuration the wing R experience a favorable upwash due to C and L, but the L contribution is fairly small. So it has a certain saving in its induced drag. But the wing C experiences the full upwash effect from both L, R and consequentially C has approximately double the saving. Good news for C! 4. If the wings L, R get pissed off at all that hard work, and drift downstream, they will experience stronger upwash due to the trailing system of C, but their influence on C will be attenuated, so they will experience larger savings at the expense of C. If they drift very far downstream, then they will have no influence on C, but L, R will still experience the induced flows of C so that ALL the saving will now be transferred to R , L. In the vernacular, C doesn't even know the wingmen are there, far astern, but they can see Cs fully developed wake lying right between them! There is a configuration providing equipartition which defines the Vee angle of this little Vic. 4. This mechanism continues for flights with larger numbers of wings. The calculations indicate, as so often in aerodynamics, that infinity is not far away, and reached very soon, so that large flights are advantageous but with diminishing returns. 5. The stability mechanism (we have the math, but its too much for here) is that if a formation were in echelon (a single skewed line) then the front bird would have a hard time, and he'd drift downstream. His wingman would then be leading and think, Jesus, I'm in front now! No way. And he'd drift downstream. This would proceed until you had about three or four birds in one file of the Vee. By that time the current lead bird would be experiencing maximum favorable induction from both sides, and would be quite comfortable and equipartition would have been achieved. 6. Steady winds have no effect on formation flight, of course. Chap called Galileo Galilei (1564-1642) had some wise words on that topic, almost a century after Leonardo had made some nearly right hypotheses re flight. But wind variation due to shear layers or turbulence due to these shear layers can always be exploited. Albatrosses use the marine shear layers to fly thousands of Km across the southern oceans with flapping a wing. This dynamic soaring has recently been validated in manned flight with a two place L-23 Super Blanik in a recent (May, 2006) USAF project out of Dryden. Energy extraction from random turbulence is also attractive, but requires wings with rapid sensing and response systems. The Santa Fe ravens are pretty good at riding the gusts of the Sangres, but its hard for machines to operate at this time scale. A Ph.D. student of mine is investigating this with a 2 m R/C IMU instrumented computer controlled flight model at Stanford. He and I are giving a paper on this at the Annual AIAA meeting in Reno this week. Its my idea of reality -- not talking, and not (God forbid!) computer simulation its a real airplane flying in a real atmosphere. 7. Flight speeds, size and other physical aspects of the wing system have no effect on the benefits of formation flight, but the savings are reflected only in the induced drag term. 8. There is no favorable drafting effect in any flight system. Drafting is always bad news for the draftee and has no effect on the lead vehicle. Anyone who has flown under tow, or seen movies of glider towing, will know that you have to stay high above your tow plane to get away from that bloody wake. Brown Pelicans are often observed flying line astern on fishing forays, but one sees each bird stays well above the preceding one. 9. All the above mechanisms apply to
Re: [FRIAM] Mechanics of Formation Flight
My thanks as well for the clear and educational presentation. If I understand correctly (which I very well may not be), then essentially all the birds, including the one at the front reach an equipartition of power output, although it sounds like possibly there is maximal drag reductions in the front three positions at the apex (depending how closely abreast the two following the leader are), and the least for the birds at the back of the vee. Getting to one of the front three positions would require a short term high power output burst by a trailing bird, which might explain why the weakest ones end up in the worst positions, since the strongest ones are able to make the short term bursts required to get into the best positions. In any event, your notes certainly require me to rethink some things, but I should clarify that my own discussions have been about the underlying principle of energy savings among coupled agents which allows for the emergence of complex dynamics among the system as a whole. Being a forest for the trees exercise, the details of the aerodynamics affect my analysis only to a small extent, although it certainly helps that I understand them. I also realize now I need to be careful about using the term drafting when types of energy savings dynamics other than drafting may be happening. Perhaps it is more accurate to refer to the principle as energy savings by coupling. Regardless, there are still universal complex dynamics that occur - for example, if there is a rotation dynamic within a vee formation, then that is a dynamic shared among rotating penguin huddles and rotating bicycle pelotons. In any event, thanks again for the very useful and helpful outline. Hugh Trenchard - Original Message - From: Peter Lissaman To: friam@redfish.com Sent: Sunday, January 07, 2007 4:59 PM Subject: [FRIAM] Mechanics of Formation Flight MECHANICS OF FORMATION FLIGHT -- PETER LISSAMAN Here are some actual facts, which folks may wish to use for discussion - on t'other hand maybe they just prefer their own opinions! Doesn't matter to anyone who just wants to ramble on a fascinating subject. I am designing flight systems to use turbulent energy, in test flight right now, so, unfortunately, gotta stick to Newton's Laws!. 1. A lifting wing develops one half its induced wash AHEAD of it. Yeah, folks, before the air has even met the wing. It's a continuous fluid, remember! The balance of the induced wash due to the trailing system develops downstream of the wing and is reaches its asymptotic value about 3 spans downstream. Within the span of the wing this induced flow is downwash, more or less spanwise uniform; outboard it is upwards, very intense just beyond the tip and attenuating rapidly as one moves away from the wing. 2. If another wing system is positioned outboard of the wing, it experiences a strong upwash, that will greatly reduce its power requirements. This effect is mutual, and its integrated intensity depends only on the tip separation as a fraction of span. 3. Consider three identical wings, line abreast, call them Left (L) Center (C) and Right (R). In this configuration the wing R experience a favorable upwash due to C and L, but the L contribution is fairly small. So it has a certain saving in its induced drag. But the wing C experiences the full upwash effect from both L, R and consequentially C has approximately double the saving. Good news for C! 4. If the wings L, R get pissed off at all that hard work, and drift downstream, they will experience stronger upwash due to the trailing system of C, but their influence on C will be attenuated, so they will experience larger savings at the expense of C. If they drift very far downstream, then they will have no influence on C, but L, R will still experience the induced flows of C so that ALL the saving will now be transferred to R , L. In the vernacular, C doesn't even know the wingmen are there, far astern, but they can see C's fully developed wake lying right between them! There is a configuration providing equipartition which defines the Vee angle of this little Vic. 4. This mechanism continues for flights with larger numbers of wings. The calculations indicate, as so often in aerodynamics, that infinity is not far away, and reached very soon, so that large flights are advantageous but with diminishing returns. 5. The stability mechanism (we have the math, but it's too much for here) is that if a formation were in echelon (a single skewed line) then the front bird would have a hard time, and he'd drift downstream. His wingman would then be leading and think, Jesus, I'm in front now! No way. And he'd drift downstream. This would proceed until you had about three or four birds in one file of the Vee. By that time the current lead bird would be experiencing maximum favorable induction from both
