B1 Intermediate 1874 Folder Collection
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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]
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Hummingbird Aerodynamics- High Speed Video - Smarter Every Day 27

1874 Folder Collection
Furong Lai published on December 17, 2012
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