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  • Hey it's me Destin.

  • So to fly slow is one of the more difficult things to do because you don't have as much airflow over

  • your control surfaces. To fly at zero air velocity is the hardest thing to do of all.

  • Over the past weekend I've been making observations of hummingbird flight

  • in my back yard. So let's look at my observations and then we'll come back, and we'll look

  • at the science of how hummingbirds fly. You're getting Smarter Every Day.

  • [music]

  • So what does olive oil and lasers have in

  • common. Hummingbirds obviously. Dr Doug Warrick

  • at Oregon State University and Dr Brett Tobalske at University of Montana have been

  • studying hummingbirds by using a nozzle to spray olive oil

  • in the air around a hummingbird. And then they'll take a laser and then they'll

  • slice sections of the air where the olive oil is, to measure

  • the flow field. Basically it's called digital particle image

  • velocimetry. What you do is you get a picture of an oil droplet, you wait

  • some finite amount of time later and then you get another picture of an oil droplet. That gives you

  • a two dimensional visualisation of the flow field around a hummingbird, which is awesome.

  • So what you can do is you can use this information to calculate exactly

  • what the hummingbird is doing to stay aloft. In these pictures you can see here,

  • you can see vortices underneath the wing. Using this technique they

  • discovered that about 70% of the hummingbird's lift comes from the fore stroke,

  • and 30% comes from the back stroke. It's not 50-50 like I used to think it was.

  • Another thing I observed is when a hummingbird would come into the feeder, right before he'd get there

  • he would make this tail flick. I didn't know what that was so I called Dr Warrick and asked him.

  • Right now Dr Warrick and his team of biomechanists don't really know what this tail flick means.

  • They're not sure if he's changing the airflow around his body

  • or if he's changing his centre of gravity under his wings so that the can make a maneuver that way.

  • What they are doing however is making a six degree of freedom model so that they can

  • study this further. If you want to learn more about it check out the links in the video

  • description. So a lot of you have been asking about what kind of camera I've been using. It's a Phantom made by

  • Vision Research. If you want more info on it go to the description, I'll put a link there for you

  • so you can go to the website. Other than that click the bird feeder here, and uh..

  • You can subscribe.

  • Oh.. Just subscribe by clicking

  • the link below, and I hope you're getting Smarter Every Day.

  • [cough] That is...

  • That's some good stuff.

  • [music]

  • [ Captions by Andrew Jackson ]

  • Captioning in different languages welcome. Please contact Destin if you can help.

Hey it's me Destin.

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