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Science

Wind Tunnel for Birds 126

Posted by Hemos from the flying-through-the-tunnel dept.
bgood writes "'What, a swallow, carrying a coconut? ...' The Department of Animal Ecology at the University of Lund in Sweden uses a modern low-speed wind tunnel specially crafted for bird experiments. The birds are trained to fly in the 'test-section' and the tunnel can be tilted up or down to simulate ascent and descent. This link contains plenty of detail, complete with bird pictures. For those of you who yearn to build your own (non-bird-compliant) wind tunnel, you can find instructions in this Scientific American article."
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Wind Tunnel for Birds More

Wind Tunnel for Birds

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  • I'd imagine that the birds would eventually figure out that they can just glide and not have to flap their wings? I mean isn't that what airplanes do?

    • Re:Smart Birds? (Score:2, Informative)

      by mutende ( 13564 )
      I'd imagine that the birds would eventually figure out that they can just glide and not have to flap their wings? I mean isn't that what airplanes do?

      Only if the bird flies ``downhill''. A quote from the page:

      The experimenter can control the wind speed and set it to a speed appropriate for the bird species in question. He can also tilt the whole tunnel, so that the wind is inclined upwards or downwards, relative to the horizontal (+8 to -6 degrees). If the wind is inclined upwards, the bird is effectively flying "downhill". If the angle is steep enough, the bird can glide without flapping its wings.
      • Ha! Airplanes have engines! If "that" (gliding) is what airplanes do, they'd be called "gliders" and they wouldn't have "engines" (nor would you take one coast-to-coast except on days with *exceptional* thermal activity - and you'd never take one across the Pacific).

        Hint - the engines are those big things hanging down from the wing, usually one or two to a side. Another hint - don't stand in front of them when they're revved up to take-off power!
  • When other guys are domesticated and get assigned to put the birdhouse in the backyard it's a 20-minute trip to Home Depot and 5 minutes hammering the thing to a tree.

  • 007 Bird Agent (Score:3, Informative)

    by TilRock ( 196653 ) on Sunday November 11, 2001 @03:06AM (#2550245) Homepage
    This could prove to be very useful in figuring out how to build a flying robot that mimics a real bird. You could fly one of these things behind enemy lines, undetected, and spy on damn near anything you want as close as you want. Pretty far off in the future yet but a definate possibility.
    • Well yes, but it couldn't transmit radio waves because that's damn easy to detect, so it'd have to be autonomous, or its controllers would have to be really good at controlling something that can't give any feedback. Plus it'd have to be about the same body temperature as a bird, because that's also damn easy to detect. Plus it'd be highly suspicious if it got inside anywhere and did anything except look like it was trying to get out. There are much easier ways to spy on people when they're wandering around outside, such as satellites.
      • Well yes, but it couldn't transmit radio waves because that's damn easy to detect,

        Actually, spread spectrum technology makes it quite hard to detect transmissions. (To the best of my knowledge).

        Michael
      • 1. It wouldn't be diffivult to make it body temp

        2. It wouldn't really matter if it weren't because your average army camp isn't pointing an IR canera at everything that moves to see whether it is hot or not.

        3. The most probably use of this kind of thing would be to set it off from a position fairly close to the target. ait for it to have a quick look around and feed video back etc. Then return to SAS type people who set it off. They then know what's going on and are better prepared to make their move.

    • Such a device would be terrible for living birds. Can you imagine an enemy camp shooting every flying bird that comes close with a bazooka for fear of one of these devices?

      If you can make a bird "spy" thingy, then you could make it into other animals too, and soon the baddies would literally be shooting anything that moves.
    • Or...

      You could build an army of nano robots that look like ants. Those little critters can get anywhere. You could hide a whole bunch of them in bin Laden's beard.

    • My only problem with this concept is that it doesn't take into account a bird raising or lowering it's mass. It takes energy to increase or decrease altitude, and that's not what's happening here.

      Same thing with treadmills. You can tilt it as high as you want, but you're not really climbing until your body actually increases altitude.
  • I can understand wanting different angles of flight, but why do you have to tilt the whole aparatus? It would seem that being able to tilt the whole wind tunnel would be a rather difficult (ie expensive) engineering constraint.

    Is there a good reason you couldn't work out some sort of flexible tubing or other solution so that part of the tunnel could be bent appropriately without moving the whole thing? Would the effect on the air flow be so disruptive that you couldn't correct for it?

    • Re:Why Tilt the Whole Thing? (Score:3, Informative)

      by Anonymous Coward
      The problem may be that you always want the wind to be travelling parallel to the sides of the tunnel. If it is not, then you will set up turbulene due to the wind bouncing off the sides.

      So, changing wind direction may actually make it a much more complicated environment w.r.t the bird.
    • Think about gravity. Flying uphill means that the gravity is not pulling at a 90 angle to the winds direction. This is true for the real world as well as for flying in a wind tunnel. Since you can't change the angle of attack of gravity (or not easily), you need to turn the tunnel.

      • Re:Why Tilt the Whole Thing? (Score:1, Informative)

        by Anonymous Coward
        Angle of attack w.r.t gravity doesn't really enter into it. The "angle between" gravity and the wind is independent of the mechanism by which the wind is generated.

        Consider the following:
        1) Tilting the tunnel at 45 degrees
        2) Generating wind at a 45 degree angle within the tunnel using a moveable source.

        There are 2 frames of reference - inside the tunnel and outside the tunnel.

        The angle that the wind is blowing is constant w.r.t the outside of the tunnel. Therefore in both cases the angle between gravity and the wind is the same. The angle between the wind and the tunnel, however, is different. I suspect that this may be the main rational between the approach to changing the angle of attack.

        (Or, I could be on crack. :-) )
  • ...this thing is for the birds!

  • Eagles (Score:2, Interesting)

    by Black Parrot ( 19622 )

    One of the most interesting things I ever saw in a nature flick was a clip of an eagle grabing a big fish out of a lake. The fish was so big that the eagle was only able to gain altitude very slowly.

    But the interesting thing was the way the eagle handled the fish. It came up from the water with the fish turned sideways in its two feet, but over a period of several seconds it shuffled its grip on the fish and turned it pointing forwards, the way a fish swims in the water -- presumably to reduce the aerodynamic drag on it.
    • Sometimes birds miscalculate; ospreys have been known to dive into the lake, grab a fish, then have it drag them under. Then fisherman catch the fish and wonder why there's remnants of a bird skeleton embedded in the fish...

  • Compliance (Score:3, Funny)

    by Engelbot ( 24601 ) <adam@tell u m o . n et> on Sunday November 11, 2001 @03:53AM (#2550313) Homepage
    Well, *my* wind tunnel is 100% OpenSwallow 2001 compliant, and supports remote control through /dev/windtunnel. :-)

    • Well, *my* wind tunnel is 100% OpenSwallow 2001 compliant, and supports remote control through /dev/windtunnel. :-)

      There was a Microsoft development that attempted to rival the OpenSwallow development. However, since Microsoft doesn't practice full disclosure of bugs, the insectivorous swallows couldn't catch them and starved. Quite tragic.

      Still, there is a moral to the story: Microsoft sucks; Open Source swallows.

  • MRI (Score:3, Interesting)

    by threaded ( 89367 ) on Sunday November 11, 2001 @03:58AM (#2550323) Homepage
    This method only displays the surface information.

    If they could fix up an MRI (Magnetic Resonance Imaging) machine they could also get information on muscle use and blood flow.

    Now that would be neat.
    • If they could fix up an MRI (Magnetic Resonance Imaging) machine they could also get information on muscle use and blood flow.


      No they couldn't. An MRI scan requires that the part to be scanned is in the exact centre of the magnet that surrounds the bore. It also requires that the sftware that combines all of the sectional images into a 2-D slice and then a 3-D image know exactly where each image was taken from. For a flying bird exact position is variable and unpredictable. In orther words you are talking rubbish.
      p>

      • I'm sorry to say that your comments are wrong.

        An MRI scan requires that the part to be scanned is in the exact centre of the magnet that surrounds the bore.

        If you read the article, the birds do stay in an essentially stationary location. Particularly for smaller birds, even the wingtips would stay inside the zone covered by a normal MRI done on a human torso.

        It also requires that the sftware that combines all of the sectional images into a 2-D slice and then a 3-D image know exactly where each image was taken from.

        Well, the article states they are already creating 3D images of the bird via high-speed cameras.

        Instead, I would focus on speed (Can the MRI slices be taken fast enough to image an entire bird multiple times a second? Seems unlikely with the current generation of equipment), accuracy (Can the imaging be matched up to a sufficent degree of accuracy to the MRI results), or costs versus benefits (MRIs are still rather expensive.) as reasons for not persuing the MRI concept.

        • Instead, I would focus on speed (Can the MRI slices be taken fast enough to image an entire bird multiple times a second? Seems unlikely with the current generation of equipment)


          I wasn't very clear. This was what I was assuming when I made the points above. The cell size of MRI is small (order of mm cubed) and in the time taken to make a measurement, the bird will move substantially. This is what I meant by "not being in the exact centre"

          Using high speed cameras you have three or more synchronised shots of the bird taken from known viewpoints. Hence manipulation is simple as the images can be "alligned" easily. An MRI is essentially a set of data about a series of points in space rather than a projection onto 2D (as is a camera shot). Alligning these with each other for a moving object would be very non-trivial as you would have no "reference".

  • What, no benchmarks? (Score:4, Funny)

    by Anonymous Coward on Sunday November 11, 2001 @04:23AM (#2550364)
    And all this time, I was hoping to see the effect it has on rfc1149 throughput.
  • Hurricane Force Wind And Its Affect On Bird Flight.

    Crank that sucker up to 150MPH or so and see how well the bird can fly. :)
  • I wonder if people racing pigeons will buy these for pigeon training.
  • The article discusses the design and history of the wind-tunnel at length. They seem pretty proud of it. Thats cool. They also talk about trying to learn about how much energy is used by migratory birds on long flights. Thats also cool. I guess (IANABiologist) that the distance that some species, like the albatross, fly without food is pretty amazing.

    Whats interesting for me tho, is what can be learned about wing design from these birds. I don't know if a wing that really "flaps" could ever be used, but surely there must be some good "science" in the flow patterns which can be observed from a large wing in a "glide" setting. Although I doubt the tunnel is big enough for an albatross...

    Anyways, interesting science from the Swedes.

    • We actually know more about albatrosses than birds which flap energetically - an albatross flies similarly to a fixed-wing aircraft when conditions are right. This is one reason they're able to fly such long distances with such little nourishment. Among other things the wings can more or less lock in place, meaning that most of the energy expended by the bird goes to controlling angle and pitch etc in order to steer (tail plays a role, too, of course).

      Flapping flight, though, that's whole 'nother thing and not analogous to either fixed-wing aircraft or helicopters.

    • Re:Improvements in man-made wings possible? (Score:5, Interesting)

      by dhogaza ( 64507 ) on Sunday November 11, 2001 @11:22AM (#2550863) Homepage
      An interesting finding made by these guys that I didn't see mentioned on the site is in regard to flight efficiency in migratory shorebirds.

      As someone mentioned above, shorebirds have an amazing ability to pig down and generate a lot of muscle and fat in a very short period of time (a large fraction of their body weight in 24-48 hours).

      So - are they more efficient when their tank's full or empty, i.e. heavy after "refueling" or light as after a long stint in the air (they're known to migrate hundreds of miles between stops).

      The reference I saw a few days ago says the answer, measured in this wind tunnel, is that they're more efficient when their tank's full (so to speak).

      The studying of the physiology of migratory shorebirds may be important for conservation, too. There are generally limited areas in which shorebirds concentrate to feed on migration. While some migrate inland, in many species virtually all individuals migrate along the coast. And, of course, in most parts of the world coastal areas are under heavy developmental pressure. People like the beach, too...

      Examples of such concentration areas include Delaware Bay in the eastern United States and Bowerman Basin in the western US.

      And human use of natural resources also has an impact (in particular the harvesting of horsehoe crabs on the east coast, they're the source of some important chemical but I forget what exactly - we don't eat them, obviously!)

      More knowledge about the physiology of these species might help us predict the impacts of certain types of development or resource consumption.

  • One experiment goes horribly wrong... (Score:3, Funny)

    by Crag ( 18776 ) on Sunday November 11, 2001 @06:28AM (#2550505)
    Scientist #1: OH MY GOD! The tunnel is coming apart!

    Scientist #2: DUCK!

  • I've seen worse (Score:2, Informative)

    by candyuk ( 535795 )
    Loughborough University Physics Department received a grant of £250K (about $400K) to investigate the aerodynamics of Toast, and to find out why toast lands butter side down no matter what height you drop it from. Hey investigating bird flight with a wind tunnel sounds quite good.
    • I don't believe you. Show me a link to a news page that backs this up.

      • Link to an article (Score:2, Informative)

        by CTho9305 ( 264265 )
        Here [smh.com.au] is one of many: Just search google for "toast butter down".
        • Detailed calculations of the dynamics of tumbling toast confirmed my suspicions, and revealed something else: that the presence of butter was more or less irrelevant. Neither its weight nor aerodynamic properties had much effect on how toast landed. The crucial factor is purely height - and toast sliding off a plate spins so slowly that only if it falls from heights above 8ft does it have much hope of regularly landing butter-up.

          Does that mean the Zooks [amazon.com] has it right after all? And to think we, the Yooks, almost bombed them into oblivion for eating their toast butter-side down.
        • I did that and have read all about this before in new scientist and others. What I was challenging was that Loughborough uni got lots of money for it. Nowhere in the articles I read does it mention them.

  • Given that this machine recycles its
    airflow, it provides a good training
    for these birds not to shit during flight.
  • A nice popular work on flight is Hank Teneke's The Simple Science of Flight [dannyreviews.com] . One thing I particularly liked about this is that it treats birds (and insects) alongside aircraft.

    Danny.

  • This is kind of cruel if you think about it, birds pretending to fly, this is kind of like putting a dog on a treadmill and making it walk itself. Maybe it's me but i think that maybe this experiment would work better in the birds natural habitat, because numerous studies have proven time and time again that animals act really funny when placed in captivity. So any data collected would be most likely completely useless.
    • Maybe it's me but i think that maybe this experiment would work better in the birds natural habitat, because numerous studies have proven time and time again that animals act really funny when placed in captivity.

      Good thoughts. That's why I'm building my wind tunnel in the willows.

      As to animals acting funny in captivity, is that why captive chimps are almost always cast in comedies rather than dramatic roles?

  • OH great! (Score:2, Funny)

    by G00F ( 241765 )
    Something else my bird will want for christmass! Everyear fancier toys, and new ways to advertise it. . . .
  • Don't be fooled! This is all weapon research to be used on the "War against Terrorism". The bird cannon will devastate millions!
  • Wind tunnels are really loud no matter the size or speed. Back in my fluid mechanics lab I hated the damn thing because it was nearly impossible to talk to each other, and we ended up wearining hearing protection thru most of the time we spent in there. Don't you think that noise would be dangerous to the animals?

    • Re:What about the noise? (Score:3, Informative)

      by Knobby ( 71829 )

      Uhm.. Not all tunnels are loud. I imagine this tunnel is only running at 10-20mph.. At those speeds the aeroaccoustic noise should be very minimal (Noise is proportional to Velocity^4).. Assuming the motor is sized correctly, well balanced, and turning an aerodynamically clean fan, the noise levels should be very small in the test section..

      I'm actually surprised they decided to use a closed loop facility for a study like this. The cost of a closed loop facility is roughly 2.5 times the cost of an open loop facility (all those turning vanes should be airfoils) and there are air exchange issues to deal with..

      interesting project though.

  • <Humor>

    Sir, I have a proposal here for some experiments in our bird wind tunnel. Experiments on top speed, stall speed, and acrobatics.

    Sounds interesting. Who's the request from?

    A Mr. Seagull. Jonathan Livingstone Seagull.
    </Humor>
  • I don't see how tilting the tunnel is valid for investigating ascending or descending flight. A little bit, maybe, but it takes more energy to increase your altitude and less to decrease your altitude and that's different than maintaining the same altitude in an air flow that happens to be pointed up or down. But I'm no researcher so maybe it's completely valid.

    I was surprised how well-behaved the birds seem to be. When I throw bread out my back door the locals won't even come close to it until I'm well inside with the door shut! I would expect birds to get completely freaked out by this contraption. Pretty cool, wish they had more pics.
    • Birds can be acclimated to the presence of people. In falconry, this is called "manning" a bird (nothing to do with spacecraft carrying people). I visited the World Bird Sanctuary here in St. Louis a few weeks ago (pictures are in here [buran.org]) and few of the birds I looked at were afraid of people. There are even a few photos on the net -- I went with friends -- of some of us standing next to some large raptors that I could almost say posed for the camera!

      It's similar to the way stray cats that are mistreated will often be afraid of the new owners who take them in but over time lose their fear (one of the cats we had when I was a child was named 'Fraidy Cat' for this reason, which later became 'Fred E. Cat') ...

  • Funny he should mention wind tunnels -- for those who are attending Comdex this week, note that there's a vertical wind tunnel only 1000 feet from the Las Vegas convention center.

    The wind tunnel is powered by a 1,000 HP electric motor attached to a DC-3 propeller.

    It's used to practice sky diving. If you're curious, you can see their website. [flyawayind...diving.com]

    I just went Saturday with 4 others. For $45, you get flight instruction, plus about 3 minutes of "air" time. It was a total blast! My sister pocketed wind and ended up shooting up about 15 feet!

  • Regarding an earlier post and replies back...

    Animal cruelty, by it's plain definition, is when an animal is used for experimentation where the animal is made to suffer some sort of test and physical experiments. I would like to call this experiment on those lines. While it is not traditional animal cruelty, and the birds probably can't tell the difference...that is where the problem really is. I hate the fact that we use animals for any sort of study. Yes the study of birds and other animals have given us such abilities as flight (yeah, humans were MEANT to fly). While that has made communication easier, it has bought on other problems. Let me get back to the main point. The use of animals for any matter of study is a cruel act. They are kept in captivity. After a while they are used to this captivity, and will not be able to return to normal freedom even if set free. Migrating birds, might migrate, but they will return to the lab during their return flight. A lab is no place for a bird or any animal to live. There is no kind moral issue in any type of animal study and experimentation. It is just plain cruel.

    These are my morals and opinions. If you have a problem with it...then speak so, oh, and do so in english, because I hate it when some sends flamebait to me that is completely incoherant.

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