From: David Wilkinson
Newsgroups: sci.math,sci.physics.computational.fluid-dynamics,sci.mech.fluids
Subject: Re: Bumblebees flying (Was: Uncertainty Invalidates Modus Ponens)
Date: Fri, 1 May 1998 09:17:15 +0100
In article <893995974.930525@bats.mcs.vuw.ac.nz>, John Harper
writes
>In article <35482C6C.7C80@stanford.edu>,
>Brooks Moses wrote:
>>
>>But, then, as I said, I come from a world where the equations used to
>>describe flight are perfectly good math, and yet they claim that the
>>bumblebee can't fly.
>
>I have been doing fluid mechanics for a long time and I have often heard
>this, but have never seen the alleged proof that bumblebees can't fly.
>Can someone please give this proof or say where it can be found?
>
>John Harper, School of Mathematical and Computing Sciences,
>Victoria University, Wellington, New Zealand
>e-mail john.harper@vuw.ac.nz phone (+64)(4)471 5341 fax (+64)(4)495 5045
>
I have never seen this mythical proof either. Someone must have produced
some sort of story many years ago, long before anyone could understand
insect flight, based on aircraft wing theory. The aerodynamics of 4
flapping wings is very complex. Lighthill did some work on insect
aerodynamics 30 or 40 years ago that showed it was quite different to
conventional aircraft aerodynamics. He showed that, by bringing two
wings flat against each other and then moving them apart, very strong
vortices were produced which could generate unexpectedly large lift. I
think this was enough to explain Bumblebee flight. I expect others have
added to this since then but I am not up with the field.
The earlier "disproof" was based on an inadequate model but the story
has an instant and lasting attraction to the non-technical mind.
--
David Wilkinson
==============================================================================
From: "John"
Newsgroups: sci.math,sci.physics.computational.fluid-dynamics,sci.mech.fluids
Subject: Re: Bumblebees flying (Was: Uncertainty Invalidates Modus Ponens)
Date: Fri, 1 May 1998 20:58:00 +0100
There are only rumours of how the story came about. I quote the following
from an article by Ken Zetie published in the IOP's Physics World magazine
(Oct 1996 vol9 (10)) entitled 'The strange case of the bumble-bee that
flew.'
'J McMasters states that the story was prevalent in the German technical
universities in the 1930's, starting with students of the aerodynamicist,
Ludwig Prandtl at Gottingen. The story goes that a noted Swiss
aerodynamicist, whom McMasters does not name, was talking to a biologist at
dinner. The biologist asked about the flight of bumble bees and the Swiss
gentleman did a "back-of-the-napkin" calculation of the kind I described
earlier, assuming a rigid smooth wing an so on. Of course he found that
there was insufficient lift and went off to find out the correct answer.
In the meantime, the biologist put the work around that bees could not
fly, presumably to show that nature was greater than engineering, and the
media picked up the story. The truth, then as now, wasn't newsworthy, so a
correction was never publicized'
John.
==============================================================================
From: Steven Vogel
Newsgroups: sci.math,sci.physics.computational.fluid-dynamics,sci.mech.fluids
Subject: Re: Bumblebees flying (Was: Uncertainty Invalidates Modus Ponens)
Date: Tue, 05 May 1998 09:03:54 -0600
The story somehow refuses to die. John H. McMasters (Boeing) gave an
account of the back-of-the-envelope calculation in an article in
American Scientist a few years ago. Having done a decent survey of
the literature on insect flight, I find the account entirely credible.
But insect flight aerodynamics are fraught with complexities -
continuously changing angles of attack, interactions of opposite wings
at the top of the stroke, issues of how many chord lengths of travel
are needed for full lift to be developed, vortex shedding and
reformation (with opposite sign) at the bottom of the stroke, spanwise
flow, etc., etc. All of which makes back-of-envelope calculations
next to hopeless.
A little over a year ago, Charles Ellington (Cambridge, UK) pretty
well tidied up the bumblebee issue, in my opinion. Tricky business,
getting sufficiently high lift coefficient, in fact. See paper in
Nature, December ?, 1996. Also see two longer papers on bumblebee
flight in J. Experimental Biology (1990) by Robert Dudley & Ellington.
Dudley (U. Texas, Austin) is now writing a very extensive review of
the entire business of insect flight. But the book is probably almost
a year away from publication. So you'll have to make do with my "Life
in Moving Fluids."
Steven Vogel
==============================================================================
From: "McMasters, John H"
To: "'rusin@math.niu.edu'"
Subject: FW: Bumblebee Flight
Date: Wed, 13 Oct 1999 12:47:46 -0700
It's your web site so you get a helping of the below as well.
[message below is a cc: of email to several people mentioned above -- djr]
> From: McMasters, John H
> Sent: Wednesday, October 13, 1999 12:28 PM
> Subject: Bumblebee Flight
I was stumbling around on the web a couple of days ago and came
across a site http://www.math.niu.edu/-rusin/known-math/98/bees that
has a string of exchanges from the addressee of this note. Well this
is kind of old by now, but I was surprised to find my name mentioned
by one of the correspondents, and since there was no clear resolution
of the issue, i thought I'd "finish the job" in case anyone still
cares.
A long time ago [1989] I wrote an article for the journal American
Scientist entitled: "The Flight of the Bumblebee and Related Myths of
Entomological Engineering" (Am. Sci., Vol. 77, pp. 164-8). In this I
gave what still appears to be a correct account of the "Didn't the
aerodynamicist prove that the bumblebee can't fly ? [sarcastic ha ha]"
story. I too had tried to find the name of "The aerodynamicist" who
did this to us. After a long search I was told by a very reputable
source that he thought that individual (who was badly misrepresented
subsequently by the "press") was the Swiss gas dynamicist Jacob
Ackeret - a famous name in supersonic aerodynamics. It was about the
right vintage, so I wrote that in my article without naming Ackeret
explicitly. Follwoing publication, however, I got mail. Boy did I
get mail - including half a dozen xerox copies of portions of the text
of the book Le Vol Des Insects (Hermann and Cle, Paris, 1934) by the
famous entomologist August Magnan. On page 8 of the introduction, one
finds:
"Tout d'abord pouss'e par ce qui fait en aviation, j'ai applique' aux
insectes les lois de la resistance del'air, et je suis arrive' avec
M. SAINTE-LAGUE a cette conclusion que leur vol es impossible."
Thus the culprit is finally named: Sainte-Lague, Magnan's lab
assistant who was apparently some sort of engineer. Steve Vogel has
correctly added some of the rest of the story and there is more to
come thanks to the miracles of high-speed photography and advances in
computational physics. As an aside, anyone who hasn't read Steve's
wonderful books should. They are classics - all of them.
Share and enjoy.
John McMasters
Technical fellow
The Boeing company
Seattle, Washington