Peter -
Another great anecdote from the annals of aeronautics...
I am wondering at your reference to
/Whether the birds also know this is another question, although the
advantages are so great (a theoretical 45% reduction in induced
power) that one assumes they must have noticed./
While I share your apparent doubt that the birds know this to be a
"globally optimal" formation, it seems they would easily notice that
their position relative to the one ahead of them en-echelon, based on
the local aerodynamics they are experiencing, is "locally optimal"?
- Steve
The Joys of Groupies
I have read the interesting comments on the advantages of fish
schooling.It all sounds reasonable, and is well worth hypothesizing.I
like dealing with prosaic facts and observations, and quote a few
established examples of avian and aviator group behavior that readers
may enjoy.
We know that formation flight, both the Vee and Echelon (one-sided
Vee), confer significant aerodynamic benefits in reducing induced
drag.I have fooled with this for some time now, from a 1971 paper in
Science to a 2007 publication in AIAA.
Whether the birds also know this is another question, although the
advantages are so great (a theoretical 45% reduction in induced power)
that one assumes they must have noticed.But there are other missions,
and rationales for other formations.A particular hunting formation of
the Brown Pelican (thriving again on the Pacific Coast since the
abolition of DDT) is to fly a few meters above sea surface in roughly
line-astern formation (actually with just enough echelon to avoid the
wake of the flyer ahead).Lead bird will spot a surface prey, fold
wings, dive almost vertically and snap up the imprudent fish.The
standard operating procedure is to snag the prey with the front of the
beak, that has a small hook, then to open beak, and smartly toss the
fishie into the back of the gullet whence it can be swallowed.Doesn’t
always work – there’s many a blip twixt beak and belly!
If No. 1 misses fishie is left flopping around on the surface. Perhaps
cursing his folly, but thinking he got away with it!Then No. 2 in the
flight rolls over and takes a crack.It’s an easier target.Usually if
all ahead have failed No. 6 will administer the coup-de-grace.I have
observed this pattern for 40 years, and last week on a visit to the
Coast, was delighted to see they still know how to do it.
Bio-mimetics is a buzzword today.It is interesting to recognize that
this pelican attack formation was copied by dive-bombers to great
effect.In the Battle of Midway, and many others, USN squadrons flying
the grand old Douglas Dauntless - the SBD (pilots claimed it meant
“Slow, but Deadly”) - would attack target from astern (or out of the
sun) in line astern, but from both port and starboard (to split the AA
fire), often with the flight commander last in the line. It worked
very well for us, due to courage and skill more than luck.
The birds won’t say why they do things. One can’t talk to the animals,
but can to people.In my youth, I was privileged to talk to the
designer of the SBD, Ed Heinemann, and to work with many USN aviators
who had been part of the Pacific War.Damned lucky we were to have
then.We shall not look upon their like again!
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:(505)983-7728
============================================================
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
