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The Joys of Groupies

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plissaman

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

Steve Smith

Re: The Joys of Groupies

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