Aerodynamics of Birds

AdamZ

AdamZ

Touchdown! Greaser!
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Display name:
Adam Zucker
I was just watching the Aeronaut posted by tristan. As I watched the animation I noticed the guy was gliding on wings but had no vertical stablizer. Then I thought Hey Birds don't have one either their wings are like wings on a plane and the tail I assume acts like a horizontal stablizer but what do the use for a vertical stablizer or to replace a veritcal stablizer?
 
Bird's kind of looks like Bonanza's Ruddervator. I think that's what it is.
 
its probably a cross between a ruddervator and the most advanced flight control system (aka a brain). The B2 can do it, so can birds. If you watch closely you'll notice that they are always making minute adjustments to individual feathers.
 
It is like a V-tail. They twist the tail feathers on the axis of their "fuselage" to coordinate turns.

Just watch birds fly for a while and you'll see it.

That's probably why the Wright brothers thought you needed wing warping vs. ailerons.

BTW, I thought the same thing when I watched the short. There's no way he could fly like that without some more control surfaces. Hey, it was a student production. He had enough work rendering the guy's face.
 
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Also, my theory is this: A bird does not have an engine out front that is creating P factor, spiraling slipstream, torque, and all that other stuff that has to be compensated for.
 
from my observations, and others, im pretty sure that birds do skid their turns. but they also have a pretty good way to prevent stalls, like they can actually FEEL the airflow, not just feedback through the airframe. no stall no spin. when watching birds thermal it seems that they turn extremely flat, likely to keep the maximum wing area exposed to rising air.
 
Wingtip feathers play a big part in maintaining stability. That is what the Wright's observed and tried to mimic when they came up with their wing warping system.
 
http://www.pbs.org/wnet/nature/raptorforce/video.html

I think this has been posted before. But these videos are really good. It should play the Peregrine Stoop one as you open the page, but check out the "Nature's Top Gun" video at the bottom as well. I wouldnt call it a spin but the Peregrine Falcons tuck in a wing and do a rolling manuever called a "stoop" in their attack sequence. Pretty incredible manueverability there, I think the video says up to 25 G's. The camera mounted on the bird in the Natures Top Gun video is just phenomenal.
 
Birds can also adjust angle, spread, and twist on EACH primary flight feather on the wings as well as the tail.

I've seen birds in a spin--but...uh, they were gun-assisted.

Also, my own birds have stalled and crashed (fortunately not getting hurt) trying to fly while wet!!
 
I've been fascinated by this question.

I think that the bird can sense the air along their bodies much better, and I believe that they ruffle their feathers on the wing that is leading when they fly uncoordinated, so that they have some type of active yaw dampening. I guess that the ruffled feathers have more drag than the downwind wing, so that they quickly realign with the airflow. From the birds I see in Manhattan, none of them seems to fly uncoordinated in their turns, even when they glide.

I'm going to ask a friend that studies bird and insect flight, stay tuned.
 
Greg Bockelman said:
Also, my theory is this: A bird does not have an engine out front that is creating P factor, spiraling slipstream, torque, and all that other stuff that has to be compensated for.
Click to expand...

But they do have adverse yaw.
 
tonycondon said:
from my observations, and others, im pretty sure that birds do skid their turns. but they also have a pretty good way to prevent stalls, like they can actually FEEL the airflow, not just feedback through the airframe. no stall no spin. when watching birds thermal it seems that they turn extremely flat, likely to keep the maximum wing area exposed to rising air.
Click to expand...

I suspect that at least some birds are able to avoid slipping inadvertently simply because coordinated flight is more efficient and efficiency of flight would be a good survival characteristic. A related question is do any birds deliberately slip when the increased drag would be an advantage to them?
 
I've seen ducks do a half roll to loose altitude. It's a little weird to watch- they roll left (for example), then roll right- I never see them finish the roll.

Other birds I see just "back pedal" with their wings if they are a little fast on landing.
 
Could I learn from ducks rather than spending $150/hr in a Super D? :confused:


:goofy:
 
This logo was on every Cessna ad in 1961 (except, for some unknown reason, ads for the Models 310 and 320 ... ;)):

ask_any_bird.jpg


-- Pilawt
 
i like that. and yes Kenny, you can learn a lot from watching the birds and not just about aerobatics. doesnt cost a thing and thats how the pioneers learned.
 
I often thought about setting up a bird feeder in my back yard and just watch the birds come in and eat off of the feeder and just study them.
 
Birds of prey and water fowl will often perform skids, slips, or high AoA maneuvers. I suspect if birds were not such masterful flyers they too would purposely enter into spins. I've watched for hours while Pelicans enter into steep spirals and often at the last second will change their surface target. I've seen Peregrines roll inverted while they track their airborne target.
 
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Tarheel Pilot said:
I often thought about setting up a bird feeder in my back yard and just watch the birds come in and eat off of the feeder and just study them.
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just make sure you don't end up following the example of the finches that my parents enjoy watching .... my grandmother called them "assup finches" from the way they feed from the feeder ... :D
 
gkainz said:
just make sure you don't end up following the example of the finches that my parents enjoy watching .... my grandmother called them "assup finches" from the way they feed from the feeder ... :D
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Floating ducks do that when they flip over to dive for food. I thought of the 1950's hairstyle called the DA.
 
Also remember that a bird can "bank" its tail too. I'm sure that makes a difference. Also, what about hanggliders, they dont have a vertical stablizer (most dont). And also like they said, birds just "know" how to fly which is one thing that frustrates every pilot. As much as we wish to think, we weren't born "knowing" how to fly. A lot of it does have to deal with just knowing every feather on a bird and how each one interacts with the wind in different ways.
 
tonycondon said:
i like that. and yes Kenny, you can learn a lot from watching the birds and not just about aerobatics. doesnt cost a thing and thats how the pioneers learned.
Click to expand...

Tarheel Pilot said:
I often thought about setting up a bird feeder in my back yard and just watch the birds come in and eat off of the feeder and just study them.
Click to expand...

Don't emulate everything they do:no:

I once saw a seagull steal a steak off a boat's stern bar-b-que out at Block Island. The bird was so over gross weight that it flew in ground effect (water effect?) making little circles in the water with each wing beat. The bird couldn't climb so it had to fly around the boats in the anchorage. I never could figure how it managed the weight & balance- I'd guess it would be way nose-heavy! It was amusing to see the guy come out of the cabin to flip his steak and wonder where it went.:)
 
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