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> fat reserves to increas
Quoting David & Alison Webster <dwebster@glinx.com>:
> Haldane was just putting the gullible reader on because angels,
> being spirits, would be weightless (or massless if you wish) so the
> wings would be used variously for ornament, supporting harps,
> modesty or maneuvering but not for lift.
* angels being visual hallucinations, the wings (and halo) are a
rationalization of their surrounding aura - http://www.julianjaynes.org/
fred.
=============================================================
> Philosophers gravely expound
> Metaphysical concepts profound.
> While they argue all night
> On the meaning of "Flight,"
> The Wrights get a plane off the ground.
>
> I leave it to evolution to iterate a useful balance between wing
> dimensions and body weight and approached the question of flight
> duration by calculating rate of fuel consumption (g tallow to keep
> one gram airborne for one second = k) and assumed no additional
> energy for forward motion; i.e. fighting gravity with a suitable
> angle of attack would provide both at little additional cost. Then
> used differential equations to allow for decrease in weight kept
> aloft as a function of time and integration to calculate the time
> required to burn a specified amount of tallow. I used 3 g initial
> and 1 g final (2 g tallow used) but any initial and final weights
> could be substituted by replacing 3 and 1 (2 equations up) with the
> other numbers.
>
> The full text, with the two typos corrected as noted and with
> spurious carriage returns thrown in is as follows--
> START OF PASTE\\\\\\\\\\\\\\\\\\\\\\\\\
> Hi Chris & All, Jan 7, 2002
> Your post about 70 hours of non-stop flight got me wondering about energy
> equivalents of fat reserves so I cobbled together an estimate of the
> upper limit.
> This is unfamiliar territory so don't bet your life savings that
> this upper imit
> is correct. Assumptions are 100% efficiency and zero energy consumed by life
> processes; obviously both wrong but I don't know probable values of
> efficiency
> and metabolic consumption. No energy is reserved for air resistance
> or forward
> motion, the idea being that forward motion is a practical way to
> climb against
> gravity and maintain height.
> GIVEN, ASSUMED:
> Acceleration due to gravity (a); a = 980.665 cm/sec^2,
> One gram.cm = 2.3427 x 10^-8 kg.cal,
> Tallow heat of combustion = 9.5 kg.cal/g
> Model bird weighs 3 grams, 2 grams being tallow.
> GRAMS TALLOW TO KEEP ONE GRAM WEIGHT AIRBORNE FOR ONE SECOND:
> A body at uniform acceleration a, will move in time t, a
> distance equal to s,
> i.e.
> s = 1/2 at^2
> So instantaneous ds/dt, to overcome gravity, is
> ds/dt= at cm/sec = 980.665 cm/sec
> So the work (energy) required to keep one gram weight airborne for
> one second is
> 980.665 gram.cm which is equal to
> 980.665 x 2.3427 x 10^-8 kg.cal = 2.297 x 10^-5 kg.cal .
> And the grams tallow required to keep one gram weight airborne for one
> second,
> call this k, is
> 2.297 x 10^-5 kg.cal/ 9.5 kg.cal/gram= 2.4183 x 10^-6 grams tallow/grams
> weight.seconds
> TIME THAT MODEL BIRD CAN REMAIN AIRBORNE; 3 GRAMS WEIGHT INITIAL, 1
> GRAM WEIGHT FINAL, 2 GRAMS TALLOW USED:
> So if w is instantaneous bird weight, the loss in weight per second will be
> dw/dt= kw and conversely
> dt/dw= 1/kw and dt= 1/k x dw/w
> and T, the seconds to burn 2 g tallow, is the integral (int) of 1/k
> x dw/w, i.e.
> T= 1/k x int(dw/w)
> = 1/k x (ln w + c) and for initial and final values of 3 and 1 grams is
> =1/k x [(ln 3 + c) - (ln 1 + c)] COMMENT =>+
> = 1.0986/k
> = 4.5428 X 10^5 seconds
> = ~126 hours
> Note that (ln 30 - ln 10) is also equal to 1.0986, so as long as
> proportions of
> initial and final weight remain the same, the same upper limit for airborne
> time will apply. COMMENT ln 20 THREE LINES UP CHANGED TO ln 10
> This also explains why it is so difficult to work off that extra serving
> of rich gravy.
>
> Yours truly, Dave Webster, Kentville
> END OF PASTE\\\\\\\\\\\\\\\
>
> ----- Original Message -----
> From: Stephen Shaw
> To: naturens@chebucto.ns.ca
> Sent: Saturday, January 24, 2015 6:46 PM
> Subject: Re: [NatureNS] Semipalmated Sandpiper migratory route
>
>
> Hi Dave et al,
> This is perhaps splitting hairs because the Sandpiper (28g) and
> Blackpoll Warbler (European, probably ~10-11g) are both quite small
> birds and therefore may be nearly equivalent, but any calculation
> needs to be framed in terms of what mass has to be kept aloft. It
> would take far more fuel consumption per hour to keep a heavy crow
> (450g) in the air compared to that for a small light warbler, if
> they have similarly efficient lift-generating wings (doubtful). It
> is usually framed in terms of body mass being proportional to the
> cube of the average linear dimension (LD^3), while lift generation
> is proportional to the square of the LD (LD^2) -- so you need
> proportionally more wing lift area as the body mass increases until
> it finally becomes infeasible to fly at all -- from memory the Great
> Bustard was reckoned to be the most massive bird that could still
> manage to fly.
> I may have used this example before: biologist J.B.S. Haldane (an
> atheist) once penned a mischievous essay on the impossibility of the
> existence of angels, at least in their depiction in medieval
> manuscripts, because to power wings that size (a big LD^2) would
> require a breastbone extending down to the ground to carry the
> enormous muscles required to flap them (humungous LD^3), not so
> illustrated in the manuscripts.
> Albatrosses don't count much in this because an engineer C.
> Pennycuick (sp?) in the 1960s calculated that one species he looked
> at mostly used the updraft from wave crests to glide along on a
> sinuous path using lift energy derived from that, somewhat analogous
> to the larger scale thermals used by some migrating raptors and
> storks.
> Understanding flight is complicated.
> Steve (Hfx)
>
>
> On Jan 24, 2015, at 3:33 PM, David & Alison Webster
> <dwebster@glinx.com> wrote:
>
>
> Hi Angus & All, Jan 24, 2015
> In an e-mail of Jan 7, 2002 I estimated maximum flight
> duration based on energy content of tallow and with initial
> conditions of 3 g total weight of which 2 g is tallow to be 126
> hours (what I call weight would usually now be called mass). In
> scanning this quickly I noticed two typos but whether these
> introduced error I don't know.
> At that time Richard dug out an example which showed this
> simple model to considerably underestimate actual endurance--
> START OF PASTE\\\\\\\\\\\\\\\
> Hi Richard, Elizabeth & All, Jan 9, 2002
> <SNIP>
> > -- "A typical Blackpoll Warbler at the end of its
> > breeding season weighs about 11 grams, equivalent to the weight of 4
> > pennies. In preparing for its transatlantic trek, it may
> accumulate enough
> > fat reserves to increase its body weight to 21 grams. Given an
> in-flight fat
> > consumption rate of 0.6% of its body weight per hour, the bird then has
> > enough added fuel for approximately 90 hours of flight for a
> journey which,
> > under fair conditions, requires about 80 to 90 hours.
>
> This Warbler beats my upper limit, perhaps by being a good weather
> forecaster and using rising air currents.
> My k equates to a loss of 0.87% of body weight per hour
> compared to 0.6%
> loss in the Warbler. And when I plug 21 and 11 grams into my
> model, I get 74
> hours of flight compared to 90 hours for the Warbler.
>
> Yours truly, Dave Webster, Kentville
> END OT PASTE\\\\\\\\\\\\\\\
>
> And the link below, for the Semipalmated Warbler, has 6 days
> of non-stop flight over water (~144 hours).
>
> The Albatross beats all of the above of course by staying
> aloft for years without beating a wing. Holding wings out and
> tilting them and tail as required takes energy but still it manages
> amazingly efficient flight.
>
> Yt, Dave Webster, Kentville
>
>
>
>
> ----- Original Message -----
> From: Angus MacLean
> To: naturens
> Sent: Saturday, January 24, 2015 9:34 AM
> Subject: RE: [NatureNS] Semipalmated Sandpiper migratory route
>
>
> Can't imagine how thin that little guy was when it arrived at
> the Orinoco Delta!!
> Thanks, Eric.
> Angus
>
>
>
> --------------------------------------------------------------------------
> From: E.Mills@Dal.Ca
> To: naturens@chebucto.ns.ca
> CC: davidmary3@eastlink.ca
> Subject: [NatureNS] Semipalmated Sandpiper migratory route
> Date: Sat, 24 Jan 2015 01:31:03 +0000
>
>
> Courtesy of BCVIBirds, here is a fascinating link about the
> migratory paths of Semipalmated Sandpipers that stage in James Bay:
> http://goo.gl/at0GMZ
>
>
> I suspect that geolocators have been used with east coast
> migrants as well, but I don't have that information.
>
>
> Eric
>
>
> Eric L. Mills
> Lower Rose Bay
> Lunenburg Co., NS
>
>
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Frederick W. Schueler & Aleta Karstad
Mudpuppy Night - http://pinicola.ca/mudpup1.htm
Vulnerable Watersheds - http://vulnerablewaters.blogspot.ca/
study our books - http://pinicola.ca/books/index.htm
RR#2 Bishops Mills, Ontario, Canada K0G 1T0
on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
(613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/
"[The] two fundamental steps of scientific thought - the conjecture
and refutation of Popper - have little place in the usual conception
of intelligence. If something is to be dismissed as inadequate, it is
surely not Darwin [, whose] works manifest the activity of a mind
seeking for wisdom, a value which conventional philosophy has largely
abandoned." Ghiselen, 1969. Triumph of the Darwinian Method, p 237.
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