Hey it's me Destin.
嗨!這是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.
慢速飛行是一項較為艱鉅的任務，因為沒有多少氣流通過操縱翼。
To fly at zero air velocity is the hardest thing to do of all.
在空氣流速為零之下飛行最為困難。
Over the past weekend I've been making observations of hummingbird in my back yard.
上個週末我觀察後院的蜂鳥。
So let's look at my observations, and then we'll come back, and we'll look at the science of how hummingbirds fly.
所以來看一下我的觀察記錄，之後回來，再來了解蜂鳥如何飛行的科學常識。
You're getting Smarter Every Day.
你現在正在收看Smarter Every Day。
So what does olive oil and lasers have in common? Hummingbirds, obviously!
橄欖油與雷射的共通點是什麼？很明顯，蜂鳥!
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.
奧瑞岡州立大學的Doug Warrick博士與蒙大拿大學的Brett Tobalske博士利用噴嘴噴灑橄欖油於蜂鳥四周的空氣，進行蜂鳥相關研究。
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.
然後他們使用雷射將充滿橄欖油滴的空氣切顆割成一區一區，去測量這些區塊的流場。
Basically it's called digital particle image velocimetry.
基本上，這方法稱為數位質點影像測速儀。
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.
你要做得是取得一張油滴照片，等過了一段時間之後，你會得到另一張油滴照片。
That gives you a two dimensional visualization of the flow field around a hummingbird, which is awesome.
這兩張照片提供你蜂鳥四周流場的二度空間顯影，真是太棒了。
So what you can do is you can use this information to calculate exactly what the hummingbird is doing to stay aloft.
因此，你能做的就是利用這些資訊來計算蜂鳥到底做了什麼能夠滯留在空中。
In these pictures you can see here, you can see vortices underneath the wing.
照片中你可以看到翅膀下的漩渦。
Using this technique they discovered that about seventy percent of the hummingbird's lift comes from the forestroke, and thirty comes from the backstroke. It's not fifty-fifty like I used to think it was.
藉由這個技術，他們發現蜂鳥上升的動力百分之七十來自翅膀前拍動，百分之三十來自翅膀向後拍動，這跟我之前想的一半一半不一樣。
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.
另外我觀察到：當蜂鳥進入餵食器，就在那之前，牠會輕輕揮動尾巴。
I didn't know what that was so I called Dr. Warrick and asked him.
我不知道那是什麼，所以打電話請教Warrick博士。
Right now Dr. Warrick and his team of biomechanists don't really know what this tail flick means.
現在Warrick博士與他的生物力學家團隊並不太明白拍動尾巴的意義。
They're not sure if he's changing the airflow around his body or if he's changing his center of gravity under his wings so that the can make a maneuver that way.
他們不確定牠是在改變身體周遭氣流，或是改變翅膀下的重心所在，讓牠可以像那樣子移動。
What they are doing however is making a six degree of freedom model so that they can study this further.
然而他們在進行的是設計六個自由度的模型來更深入地研究。
If you want to learn more about it check out the links in the video description.
若你還想多瞭解一點，請點選影片介紹的連結。
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.
你們很多人問我究竟是使用哪種攝影機？這是Vision Research公司推出的《魅影》
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.
如果你想知道更多訊息，到影片介紹區，我會為你將連結放上，讓你到網站上去。
Other than that click the bird feeder here, and uh...you can subscribe.
除此之外，你可以點選 這裡的「餵食器」 ，還有啊...你可以訂閱。
Oh... Just subscribe by clicking the link below, and I hope you're getting Smarter Every Day.
噢...點選下列連結即可訂閱，希望你喜歡Smarter Every Day。
That is... That's some good stuff.
那是...那真是好東西。
