[FRIAM] The Mysterious Triangular Truss!
Wot be Cognitive Vertigo But a discussion by people don't know the topic? ANY triangle consisting of three joined members (wood or gold, and not necessarily straight, or pinned) if supported on a base will resist any load through any vertex. It is not particularly good at this and much less rigid than a single member of the truss in direct load . Leonardo used these a lot. Even made stylish cartoons of same. Called a simple triangular truss. The basis of all space frames. 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] The Mysterious Triangular Truss!
Wot be Cognitive Vertigo But a discussion by people don't know the topic? ANY triangle consisting of three joined members (wood or gold, and not necessarily straight, or pinned) if supported on a base will resist any load through any vertex. It is not particularly good at this and much less rigid than a single member of the truss in direct load . Leonardo used these a lot. Even made stylish cartoons of same. Called a simple triangular truss. The basis of all space frames. 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] A leetle thermodynamics!
Solar cookers can break your heart, but not the laws of thermodynamics. Consider this elementary fact, my dear Dr. Watson. The insolation on earth near the equator is about 800 W/m2, it is less at the end of the day, and much less after sunset. For an aperture of 0.1 m2, you getting about 80 W black body, ignoring losses. Concentrators have nuttin to do with it! This amounts to about 270 BTU/hr from which you could boil a bit less than 2 pints of water in an hour, assuming no losses. BTW, you can, with care and ceremony, make ice in the Egyptian deserts every cloudless night, by exploiting radiation to the stars from shallow water trays, and careful control of nucleation, convection and vaporization. In fact, the temple priests used to do it on the flat roofs of the temples to impress the unwashed on the bounty of whatever God they were scamming that week. Much hoopla, involving sanctified water brought up from the basement (where it had got pretty cool, mixed with yesterday's ice), throwing holy dust on the surface (to provide nucleation particles) and wafting the surface at just the right time and rate with magic ostrich featherwands to actually control heat transfer due to convection and vapors. It's just thermodynamics, Nefertiti! And if sometimes the ice didn't form, it was because someone's mother-in-law was a witch! It's amazing what them religious guys know!! I usedta teach elementary courses in thermo in CA and the conversion constants are from memory and only roughly correct. 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] A leetle thermodynamics!
Solar cookers can break your heart, but not the laws of thermodynamics. Consider this elementary fact, my dear Dr. Watson. The insolation on earth near the equator is about 800 W/m2, it is less at the end of the day, and much less after sunset. For an aperture of 0.1 m2, you getting about 80 W black body, ignoring losses. Concentrators have nuttin to do with it! This amounts to about 270 BTU/hr from which you could boil a bit less than 2 pints of water in an hour, assuming no losses. BTW, you can, with care and ceremony, make ice in the Egyptian deserts every cloudless night, by exploiting radiation to the stars from shallow water trays, and careful control of nucleation, convection and vaporization. In fact, the temple priests used to do it on the flat roofs of the temples to impress the unwashed on the bounty of whatever God they were scamming that week. Much hoopla, involving sanctified water brought up from the basement (where it had got pretty cool, mixed with yesterday's ice), throwing holy dust on the surface (to provide nucleation particles) and wafting the surface at just the right time and rate with magic ostrich featherwands to actually control heat transfer due to convection and vapors. It's just thermodynamics, Nefertiti! And if sometimes the ice didn't form, it was because someone's mother-in-law was a witch! It's amazing what them religious guys know!! I usedta teach elementary courses in thermo in CA and the conversion constants are from memory and only roughly correct. 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] Accountability: a rare courage!
The idea is that a published paper should be preceded by the names of the reviewers for and agin said work. That terrifies the profs! Still throws no light on the naysayers if a paper is rejected! 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Homeostasis by Peer Review
Peer Review is indeed an excellent preserver of status quo. For the AIAA (the main aerospace institution) the standard procedure is that the signed draft paper is submitted by editors to reviewers, who then send anonymous comments to the author. Twenty years ago, as a Fellow of said august Institution, I proposed simply reversing the process: sending the paper anonymously to reviewers and then listing favorable reviewers on the published paper. It was received with deafening silence. Actually, the Royal Society does do something akin to this. 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Art, Science Vice-versa
I reckon a rather convincing demonstration that, happily, Art is NOT like Science is that artists don't write the sort of stuff appears in Friam on the subject. 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] A Modest Query
Does anyone know why Excel SOLVER gives unrepeatable (unspeakable) results for a simple variation problem? A high order wave equation. I'll give details if you e-mail me. 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Good, Evil and the Persistence and Treatment of Fools
It is certainly unreasonable to expect people to behave rationally, especially when most of them claim to believe in a God who somehow judges and punishes! Well, one must admit that in the END there is retribution for most BAD acts - the clever thing is that it is usually the innocent who are punished. Indeed, He doth move in mysterious ways!!!But, but, but, all is not hopeless, it is for inspired leaders to fool the fools into doing good things; as exemplified by Augustus, Churchill, Roosevelt (III) and Kennedy. 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 TEL: (505) 983-7728 FAX: (505) 983-1694 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] CALCULUS, POINTS AND OTHER MYSTERIES (TO SOME)
Why can't a point have a position, speed, acceleration and any other derivative? Can't one judge calculus by results? Or by its fruits as the Good Book hath it! In the 50' and 60's I and others got folks to the moon and back using these abstract calculus concepts of old Isaac. At least they went to the moon according to the press, our earthbased Newtonian commo systems, and to two astronaut students of mine who called me afterwards and SAID they'd been there. Mebbe they weren't thinking it through carefully enough! 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 TEL: (505) 983-7728FAX: (505) 983-1694 [Original Message] From: [EMAIL PROTECTED] To: friam@redfish.com Date: 7/9/2008 10:00:32 AM Subject: Friam Digest, Vol 61, Issue 7 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. Fwd: [OS X TeX] gmane archives out of date. (Owen Densmore) 2. Re: Fwd: [OS X TeX] gmane archives out of date. (Marcus G. Daniels) 3. Sun's MPK20 (Mikhail Gorelkin) 4. Announcing the Complexity Noodlers Corner (Nicholas Thompson) 5. Mentalism and Calculus (Nicholas Thompson) 6. Re: Announcing the Complexity Noodlers Corner (Steve Smith) 7. Re: Mentalism and Calculus (Marcus G. Daniels) 8. Re: Mentalism and Calculus (Robert Holmes) -- Message: 1 Date: Tue, 8 Jul 2008 11:20:40 -0600 From: Owen Densmore [EMAIL PROTECTED] Subject: [FRIAM] Fwd: [OS X TeX] gmane archives out of date. To: The Friday Morning Applied Complexity Coffee Group friam@redfish.com Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=ISO-8859-1; format=flowed; delsp=yes Well, one can always learn! And Nick, note that I too can screw up a mail list! Here's the story: I joined the OS X TeX list. My first email to them was simply that their gmane archive was broken. But the way I did this was to view the first email I received on the list (on an entirely different topic), hit Reply, deleted the body of the email and changed to a new Subject. Basically a way to get a fresh email with the correct To: address. In other words, I used an existing email for a template for a new email to the list. Turns out this is a no-no. It confuses modern email clients into thinking this is the same thread even though the subject has changed. It certainly occurs all the time in my client (Mail.app), but I just presumed Mail.app was struggling to identify same thread-ness via context and failing. Nope. The headers keep a In-reply-to field to help in threading. So when I cloned a new email, deleting all but the to: field, I inadvertently kept the In-reply-to header field, thus screwing up everyone's email threading. (BTW: This never happens with Nabble and Forum software due to the explicit new-post/reply buttons, thus completely isolating a thread. There the etiquette is simply search before a new post to see if there is already a similar thread underway.) Sigh! But Nick, I now know what you mean by that calm, stern, reply- to-an-idiot tone of voice. -- Owen Begin forwarded message: From: Bruno Voisin [EMAIL PROTECTED] Date: July 8, 2008 12:28:21 AM MDT To: TeX on Mac OS X Mailing List [EMAIL PROTECTED] Subject: Re: [OS X TeX] gmane archives out of date. Reply-To: TeX on Mac OS X Mailing List [EMAIL PROTECTED] Le 8 juil. 08 ? 01:49, Owen Densmore a ?crit : On Jul 7, 2008, at 5:27 PM, Gary L. Gray wrote: Please don't hijack existing threads -- see the List Reminders and Etiquette link in the footer of this message. Yikes! Not sure how I hijacked an existing thread. Is there a os x tex gmane thread? Anyway, sorry! You hijack an existing thread by replying to a message from this thread to create a new message with different subject. Symptom: in emailers which support threading (such as Apple's Mail, Mozilla's Thunderbird), your new message and the various answers it will get will be classified within the same thread as the original message you replied to. Cause: by replying to an existing message, whatever new subject you enter manually for the reply, this reply will keep in its hidden headers an In-reply-to header such as (in your case) In-reply-to: [EMAIL PROTECTED] Cure: always use Address Book to create a new message
[FRIAM] It aint all Elitist BS!
The remarks about the Apex of the Vee as religious cant supporting the Old Guard are all well made. But, but, but we must remember that in the geese migration case the older birds have better navigational and weather prediction skills, so are indeed useful leaders. In the case of HMS Bounty, only Bligh and Christian had the essential skill of celestial navigation so were functional leaders by superior knowledge, and in this case, clearly not character!! 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 TEL: (505) 983-7728 FAX: (505) 983-1694 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] The Apex of the Vee
The interesting discussions relating to bussing, pelotons and human/animal behavior call to mind some papers I published at Caltech in 1969 relating to the advantages of Vee formation flight for migrating birds. Because the saving is in induced drag the least energy position is, counter intuitively, the apex (point) of the Vee. I was immediately assailed by ornithologists and bird watchers, who knew much more about the subject than I, and rather than checking the equations, challenged my results on their ideas of behavioral grounds. It turns out that the apex position is indeed taken by the oldest and strongest bird. Would he, they asked, take the easiest job? My answer was:yes.! 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 TEL: (505) 983-7728 FAX: (505) 983-1694 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] DIFFERENTIABILITY, CONTINUITY AND COMMON SENSE
I am bewildered at the plethora of verbiage poured out on the first two topics. I studied math as a grad student scholar at Cambridge and CIT, but don't understand most of the big words your correspondents use. I know, its my ignorance! But, to be constructive, I put forward a modest proposal: that correspondents holding forth on scientific/mathematical issues provide examples and algebra (or, even better, numbers) supporting their polysyllabic pronunciamentos. My advisors always gave examples of concepts I challenged. Except once, where one said, This theorem is so GENERAL that its impossible to find a good example! I did not have the temerity to respond in the immortal words of Richard Feynman, Surely you jest, Dr XXX! Your correspondent noted that F was poor mathematician. We were both on the faculty of CIT. I knew Dick and his family socially for 30 years, but perhaps it was not long enough to see that side of his Promethean personality.He was an inveterate joker, always claiming that he knew no math and mocking those who used pomposity instead of science to make a case. I am not qualified to judge his math ability, but folks who were, physicist friends from Los Alamos (in the competent Manhattan days) and CIT, marveled at Feynmans math ingenuity. So, I dunno. I'm suppose your correspondent knew him and his works better. I'm sure a FRIAM member would never make an unsupported statement. 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Diff Contin. to Nick!
2. DIFFERENTIABILITY AND CONTINUITY (Nicholas Thompson) Nick: Let me be your math consultant! Taught that stuff at Caltech many years!! The mathematicians are horn swogglin' you with mis-understood function theory! A'course the f'n roof is continuous. If it weren't the rain would come through! It is trivial to write a continuous function, f(x) defined for 0x =c and g(x) defined for cx1 with f(c) = g(c), with the peak at x=c and a different slope for x=c, than for xc. But the function is continuous. Just like a roof ridge. A geometric function has, at each point, some degree of continuity, denoted by C N, where N is the order of the first discontinuous derivative. The triangular roof frame rafter is C1, meaning continuous in ordinate, discontinuous in slope. Smoother shapes have continuity of higher derivatives. Analytic functions have infinite continuity (thanks to M. Cauchy!). Airfoils have to be very smooth, but they can't be infinity smooth, since we need to tailor the pressure distribution to control separation, and the trailing edge must usually be sharp. Some of my airfoils of the olden days, when we did this by hand, were C16 -- that is continuous only up to the 16th derivative. The airfoil I designed for the Victor B Mk II(1956) is that rough, 'cause we did things on Friden calculators in them days. But, as the RAF nuclear delivery system in the hottest days of the Cold War, it scared the daylights out of the Ruzski. The airfoil on the Gossamer Condor (Lissaman 7769) is much smoother than that, although that too was pretty primitive. I did it personally using the old (1971) TRS with punched tape inputs. I used the Radio Shack computer eksactly as Picasso recommended: as an automated calculator to make the tiring number crunches needed to provide answers to my questions. Incidentally, with a trained geometric eye, which I think I have since I've been laying out airfoils and streamline shapes since the 50's, you can see about 4 derivative continuity. But the bloody air is unforgiving and wants higher smoothness than that. It responds to curvature of curvature of curvature that you didn't even know was there. But the computer does. Artists talk only up to C3, meaning continuity of curvature. Art Deco derives a lot of its arresting visual tension by deliberately exploiting discontinuities in curvature - for example a scroll of fixed radius terminating a straight banister (C3). Art Nouveau designers would rather die than do such thing -- for them it's all swooning smoothity!! I'm sure this is more than you wanted to know, but I love digressing on this, and for 20 years gave a course at Art Center on Leonardo and his art and technology. He was not a mathematician, even by the fairly unsophisticated standards of the High Renaissance, but how he longed to express things mathematically!! 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 TEL: (505) 983-7728 FAX: (505) 983-1694 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] It's the Spies, Stupid!
Thanks to all who responded in much more courteous terms than my present title! A'course, it reminded me and well should I have remembered! But old men forget as da Bard had it (Lear). My old tutor (thesis advisor in these parts, (one S.W., for those in the know )) was one of the Bletchley Boys who cracked Enigma in WW II. And, as a math grad student, I well remember more than 1/2 century ago hearing his tales as we looked out over the rainy rooftops of Cambridge! A'course, the Enigma Machine was entirely deterministic, mechanical, but verrray complicated. Wheels within wheels!! New setting each morning! I can imagine some totally bored Wehrmacht Feldwebel cranking away at this horizontal axis coffee grinder while he slurped his ersatz Kaffee and wished he had some sugar!The Brits said, languidly and typically Englishly, we usually managed to 'sort out' the day's code by tea time. Also, being an honorable Englishman, (there were still a few left then), my tutor said very little of substance because the Official Secrets Act ran for 50 years. My remarks are really meant entertain, so thanks to all for putting up with this BS!!! 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 TEL: (505) 983-7728FAX: (505) 983-1694 [Original Message] From: [EMAIL PROTECTED] To: friam@redfish.com Date: 7/22/2007 10:02:51 AM Subject: Friam Digest, Vol 49, Issue 20 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. Why true random? (Peter Lissaman) 2. Re: Why true random? (Robert Holmes) 3. Re: Why true random? (Russell Standish) 4. Re: Why true random? (Prof David West) 5. Re: Why true random? (Phil Henshaw) 6. Re: Why true random? (Douglas Roberts) 7. Re: Why true random? (Phil Henshaw) 8. Re: Why true random? (Roger Frye) -- Message: 1 Date: Sat, 21 Jul 2007 10:24:42 -0600 From: Peter Lissaman [EMAIL PROTECTED] Subject: [FRIAM] Why true random? To: friam@redfish.com Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=us-ascii Why is it important (except intellectually) to have true randomness??? I very well remember the early, good old, bad old, days of Aerospace, in the 50's, when we were really doing practical earthshattering things -- like going to the moon -- sans computers!! The RAND corporation, for whom I consulted, published a typed book (size of a Manhattan telephone directory) of random numbers for engineering application. Much entertainment was occasioned when, about three months later, they distributed a list of typos to their original list of random numbers. Today I use homemade random numbers alla time for real problems, specifically the actual response of real flight vehicles in real atmospheric turbulence. Flight tests support analysis, in the sense that what we predict is not obviously incorrect. We have never found it necessary to utilize any more perfectly random random sequences! 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 TEL: (505) 983-7728 FAX: (505) 983-1694 -- next part -- An HTML attachment was scrubbed... URL: http://redfish.com/pipermail/friam_redfish.com/attachments/20070721/e01d235d /attachment-0001.html -- Message: 2 Date: Sat, 21 Jul 2007 13:34:44 -0600 From: Robert Holmes [EMAIL PROTECTED] Subject: Re: [FRIAM] Why true random? To: [EMAIL PROTECTED],The Friday Morning Applied Complexity Coffee Group friam@redfish.com Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=iso-8859-1 Cryptography. The required robustness of a random generator is highly sensitive to the intended application; - Generating a thought for the day for your blog? Required randomness = low. - Response testing a missile system? Required randomness = medium - Stealing above test results, encrypting them and transmitting them to Al Quaeda in a form that you hope the NSA won't understand? Required randomness = high Robert On 7/21/07, Peter Lissaman [EMAIL PROTECTED] wrote: Why is it important (except intellectually) to have true randomness??? I very well remember the early, good old, bad old, days of Aerospace, in the 50's, when we were really doing practical
[FRIAM] YELP, HELP!
Does anyone know a computer wizard who will come (for $) to my home in Santa Fe, and fix a recalcitrant laptop which seems to be surfing in molasses! I know it defies laws a' probability but the last four I paid knew less than I! 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Will Rogers and Animal Behavior
When he was given a brief description of the learned theories of Dr. Freud, and told that they accounted for all human behavior, Will Rogers stated that: he found it real interesting, but reckoned that in Oklahoma, folks mainly did things jes' acause they felt like it. I gave a paper at AIAA annual meeting in Reno earlier this week on birds extracting energy from turbulence. There's a lot in it for the birdies, with their low flight speeds, superb sensing and rapid response. Ravens in Santa Fe are marvellous aerobats in the turbulence rolling off the Sangres. But why? When you see them rolling off perfect chandelles, as with dolphins surfing and gamboling in the bow wave, you have to admit that they're jes' havin' fun, contrary to these gloomy animal behavioristos who claim animals do everything for a reason. 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Anecdote vs Observation
Yogi Berra said, You can observe a lot by just looking around. I am not an ornithologist, so really have only anecdotal knowledge of bird formations, derived from my own un instrumented and un scientifically recorded sightings, so I dunno much here. They're not observations in the scientific sense. And I've been looking hard at birds only since 1969. The only birds I have ever seen in Vee formations are brown and white pelicans and various large migratory geese and swans. I have watched many times the big Vulture (Aasvogel) of East Africa, where I was born. They do not formate and HATE company. Doan wanna share their supper! Ravens do not formate but they sure fool around. Now folks who know what they're talking about (unlike me) say that the rough and tumble play of cubs and puppies is a training for fighting and killing in the adult state. Maybe, and maybe ravens whooping it up in the turb is a training for evading redtail hawks and other predators that bag them. Yeah, yeah! I do know fighter and test pilots though, professionally, and they certainly fly aerobatics to improve their emergency, evasive and killing skills, but they still LOVE doin' it! This really exhausts my professional knowledge, indeed goes a little beyond it, so I reckon I'll sign off and leave the subject to the innocent and the eager. 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 TEL: (505) 983-7728FAX: (505) 983-1694 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] Research in Formation Flight
The video of frigate birds is charming but says nothing. Anyone who can read anything from that must be an astrologer. (I'm an Aquarian and Aquarians don't believe in astrology!). Mebbe two lions ambling side by side across the bushveldt are practicing drafting! You can bet they're sniffing the breeze for a few foolish upwind hunters! But, but, but, the wings of frigate birds are indeed interesting, because the highly tapered tip planform is contrary to established aerodynamic theory. We dunno why! I have a Ph. D. student at USC working on this. It seems wise not to use the word draft incorrectly, it has a well-defined meaning among professionals. There is no issue of whether there is a physical principle underlying formation flight - this has been established since Wieselsberger (1914). I'm told that Doktor W. went on to help the design of the Albatros D.III, a favorite gun platform of Von Richthofen! Benefits of formation flight are supported by a large body of research. In fact, the field is overripe in research to the level of decay. There is a huge amount of professional stuff in the aerodynamic and ornithological literature. There's a nice recent Ph. D. thesis by Rachel King that I had something to do with (On the Use of Wing Adaptation Formation Flight for Improved Aerodynamic Efficiency, NCSU, 2005). It contains a 69 entry bibliography, all legit., I think!Her supervisor, Ashok Gopalakrishnan, knows a lot more than I about this topic - I've only published six papers on it and given one grad course on this at UCLA. Also one can find stuff in Google that provides a start, if slightly dangerous! Google has an extract from a bit I wrote on formation flight for Tony Filippone's book, Flight Performance of Fixed and Rotary Winged Aircraft (Elsevier, 2006). The extract is slightly wrong, but OK in many respects. Be careful of web material - lotsa stuff I've found in Wikki on advanced mathematics is incorrect.Trubble is -- how the hell do you know it's BS -- if you don't know already!! 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 TEL: (505) 983-7728FAX: (505) 983-1694 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
Re: [FRIAM] Friam Digest, Vol 43, Issue 6 Formation Flight
In connections with the comments about FORMATION FLIGHT FORMATION FLIGHT by PETER LISSAMAN The formation flight of birds has long been of interest to natural scientists. Leonardo da Vinci discussed this in 1504, as did Lord Rayleigh in 1889. The Vee formation produces significant energy saving. There is no debate about this. It has been established unequivocally theoretically, measured in flight tests with aircraft, and also, indirectly, in the remotely monitored pulse rate of formations of our feathered friends, actually Brown Pelicans. The mathematics is complicated. It relates to the flows induced by the vortex wake behind a lifting wing. Outboard of the wing a large upwash is induced, proportional to the circulation on the wing, and the wing man (bird?), if he tucks up tight on the tip, is flying in a strong upwash, with big drag savings. Thats all there is to it! But, Ah, the Details! As Leonardo said God is in the Details! It would be boring to go into those mathematics, except to say that the procedure is considered well-understood and correct, but a helluva mess! The birdies jus' do it, and could care less! The first paper I know of that treated the topic mathematically (and brilliantly) was Wieselsberger in ZFM, 1914; and there has been a fairly lively activity since then, as computers have removed the formidable and intelligent math required, and made it possible for anyone to get results without understanding them. In 1969 Carl Shollenberger, my valued friend and colleague, and I worked on this, and published the results in Science. The paper (Lissaman Shollenberger, Formation Flight of Birds, Science, Vol. 168, 1970) shows the very large size of these savings. We used the impressive new IBM 360 computer at Caltech. It occupied a three storey building about the size of a four unit apartment block, and had mens and womens toilets inside, as well as 12 real people who punched cards, fed data and generally dealt with the I/O. One picked up outputs at about 3:00 am each night. My wife never really believed that was what kept me up, although I did my thesis on mathematics of wing theory some years before using that old 360! And used the same story! Computation is clumsy, but more than Doktor Wieselsberger ever had! Carl was killed a few years later, flying in night mountain turbulence over the Sierra Madres. It was a great loss to aviation he was a fine pilot and aerodynamicist. I acknowledge his contribution fondly. He would be glad that his work was still used. Recently I revisited this subject in a paper Simplified Analytical methods for Formation Flight (Lissaman, AIAA. Jan. 2005) and next week will give a paper Neutral Energy Cycles for a Vehicle in Sinusoidal and Turbulent Vertical Gusts (Lissaman Patel, AIAA. Jan 2007) The Science paper shows that in theVee, for tight formations, one can almost double the range for a given energy input. Also that there is a stability mechanism, by which a member finds that moving ahead of the line of the Vee requires power increases. So theres a comfortable groove to fall into, which animals love! One should always be skeptical of attributing effects derived from theoretical calculations to animal behavior, but the general consensus of ornithologists and aerodynamicists is that this Vee formation saving is so significant, and its application so ubiquitous, that migrating birds DO use it to extend their range. The paper addressed the savings for different positions in the Vee. In line abreast, the center birds experience twice the saving of the tip members, but if the tip members find this hard work and fall back to take advantage of the increased favorable downstream upwash of the vortex wakes of the inner members, then a balancing of savings occurs. We calculated the angle of the Vee for equipartition. It is about the same as is observed with migrating birds. We also showed that it was not necessary have equal legs of the Vee. Provided there are at least about 6 birds on one side of the Vee, the other leg can be almost as long as the birds choose to make it. 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. They wondered why the more powerful members of the flight should take the easiest jobs! My answer was that most intelligent species are pretty anthropomorphic! It may be noted that the savings are not related to drafting, that is following behind a draggy object to take advantage of its lower dynamic pressure wake. I am very familiar with this, and, as an automobile aerodynamicist, have utilized this theory in race car design, and as is obvious, the slingshot maneuver is very significant. But not in flight! It is, in fact, horrible to fly
