Birds Give a Lesson to Plane Designers

Roland Piquepaille points out a news release from the University of Michigan where researchers are looking to birds and bats for insights into aerospace engineering. Wei Shyy and his colleagues are learning from solutions developed by nature and applying them to the technology of flight. A presentation on this topic was also given at the 2005 TED conference. From the news release: "The roll rate of the aerobatic A-4 Skyhawk plane is about 720 degrees per second. The roll rate of a barn swallow exceeds 5,000 degrees per second. Select military aircraft can withstand gravitational forces of 8-10 G. Many birds routinely experience positive G-forces greater than 10 G and up to 14 G. Flapping flight is inherently unsteady, but that's why it works so well. Birds, bats and insects fly in a messy environment full of gusts traveling at speeds similar to their own. Yet they can react almost instantaneously and adapt with their flexible wings."

G-forces planes withstand are pilot-limited

[Anonymous Coward]

The fact that the current crop of planes is limited to about 8-10 Gs is because that's all the pilots can withstand.

Re:Missing tag.

[Anonymous Coward]

Its the scale effect. The scale at which the physical laws act is the same. Its not possible to make a human size water strider.

Re:Missing tag.

[calebt3]

***Warning: Hearsay below***

Apparently once upon a time all articles submitted by Roland linked to his blog which linked to the real article (as a way to generate ad revenue, I think). And he continues to take flak for it to this day.
Like I said, this is second-hand from earlier discussions. I was not here when it was happening.

Re:Missing tag.

[amorsen]

Considering that the laws of physics scale uniformly with size (as long as we're talking about objects bigger than a molecule and smaller than a planet) this shouldn't matter.

Where do you get this junk from? Mass increases cubically when wing area increases quadratically (and wing span increases linearly).

Were an enormous 11,000kg unladen swallow to exist, it should exhibit pretty much the same characteristics as the 10g swallow, with a slight penalty for increased air resistance.

With the slight difference that the 11,000kg swallow would not be able to stand up, much less fly.

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[account_deleted]

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Re:PILOTS are limited to 8-10 G's not the planes.

[icebrain]

Not really... most are set at about a 15 degree angle; the F-16 is reclined to 30 degrees. That was first done to be able to fit the seat in the aircraft, and the small G-load benefit was discovered later. I think the F-22 and F-35 may also be set like that, but I'm not sure.

Re:Missing tag.

[jc42]

All this had to work the very first time.

Again, no. The first flocks that set out at random either end up in the ocean, or find land. Those that find land will do this because they had enough food to do this. If each bird in the flock that found land had a random amount of fat, half of them would drop to the ocean, but half would arrive and breed. They would get kids that had genes that would make them eat a little bit more than the imaginary kids from the birds that died. Now repeat for millions of generations, and you'll end up with something quite optimized.

All very true, but you missed the fact that when they started out, Hawaii and Alaska were closer. Today's Hawaiian Islands are the end of a long chain of seamounts that stretch out nearly to the Aleutians, with the seamounts getting older as you go northwest. We don't know when those plovers started this migration, but it was some millions of years in the past, when the end of the Hawaiian chain was one of those older seamounts that was then an island. It could have even been back when the islands were barely offshore from the then supercontinent of Laurasia (though it should be mentioned that we don't know this).

So their ancestors that started this migration had an easier job of it. As the islands slowly drifted out to sea, each generation would be selected for the survivors that were able to make a slightly longer flight.

Environmental change, in this case the effect of a moving geological "hot spot", must be taken into account to fully explain a lot of evolutionary events. That's one way you can get results that seem impossible in today's world, especially things like the colonization of remote islands like Hawaii by species that can't cross the open ocean.

Re:PILOTS are limited to 8-10 G's not the planes.

[Anonymous Coward]

I wonder what forces the pilots could withstand if they piloted in a prone position, though I can't imagine that being very comfortable.

It had been tried out on an Yugoslav early experimental plane [airliners.net] (on display in Museum of Aviation in Belgrade [jat.com]) in 50's and it really gave significant advantage in endured G-force. However, visibility from cockpit was much impaired and idea was rejected as impractical for fighter planes (other aircraft types not needing such maneuverability anyway). It is an example of how out-of-the-box thinking is much praised, but only occasionally makes real breakthroughs. Perhaps this old idea combined with modern VR equipment and external cameras ... but wait, if you already have all that, you don't need to strap a human pilot into it, you can fly it over remote control radio link instead.

Re:Young Researcher Linked Owls to Airplanes

[Napoleon The Pig]

The idea of using wingtip devices to control vorticies has been around for over 100 years. Frederick Lanchester (a conteporary of Prandtl) secured a patent in 1897 for the use of "bent up wing tips" to control tip vorticies. He was working on those theories at the same time the Wright brothers were trying to learn how to fly. It took 20 years for aerodynamicists to prove his theories correct.

Re:Missing tag.

[sk8king]

As you get bigger, the cross sectional area of your muscles and bones increases at the rate of L^2 [where L is the length], but your mass increases at a rate of L^3.

As your size increases, your mass quickly outstrips the ability of your muscles and bones to sustain it.

Interestingly, as your size decreases, it works the other way. Mass decreases at a cubic rate and strength [muscles/bones] decreases at a square rate. You become relatively much stronger.

Gerbils can survive falls from any height, elephants break at 5-6 foot drops.

Re:Missing tag.

[nmg196]

This thread relates to Golden Plovers. http://pbc.codehog.co.uk/bhs/pics/200611/golden_plover_flock_19nov06_800l_20a.jpg [slashdot.org]">They do NOT fly in a V formation - they fly in a very random flock.. Very few small birds fly in a V formation. That tends to be larger birds like geese.