Name: Helicopter Physics Series - #5 Autorotation = NO PARACHUTE! - Smarter Every Day 50
Uploaded: 2020-03-26T02:45:33.000Z
Duration: 4 min 40 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Hey it's me Destin.Welcome back to Smarter Every Day.  We're right in the middle of a

series on helicopters and we're gonna talk to you about.. What is this called? (son) Parachute.

can have a parachute so if anything  goes south he can jump out

and he can parachute to safety. Do you want to test the parachute real quick?

(son) Yeah I'll do it. OK we're gonna use the parachute off the balcony here. Check this out.

We just gave the parachute man to our neighbours.

So think about this. Let's say we're in a helicopter

and we're up high and all of a sudden we run  into trouble when we run out of engine power

and we start to fall.  So we've got this weight and it's

suspended by this rotor system.  Now if we're smart about it we can

change the pitch on our blades to  spin up our rotors really really fast.

And then we have kind of like a  pinwheel or a windmill effect.

And if we're really smart, right at the last minute,  right before we hit the ground,

we can change the pitch on those  blades to provide lift. So we're

back driving our rotors and then right at the last  minute we're using them to

decelerate, right before we hit the ground.  This is a manouver called autorotation,

and this has kept helicopter pilots alive  for many many years.

In fact, they've even done autorotations from 40,000 feet.

So a helicopter basically has a built-in parachute. But with a helicopter you've got this

rotating disc right in front of you.  So my question is, what happens if you lose power

at altitude. So this battery he just put in, what if it dies. So what happens Carl?

(Carl) If you lose power in a helicopter you can autorotate. Alright.

So Carl's gonna demonstrate autorotation and  we'll get an idea for what happens.

Alright so what exactly are we about to do here?

(Carl) We're gonna demonstrate autorotations.  I'm gonna take you up a couple of hundred feet up in the air

shut the motor off, and fly it all the way  to the ground without power.

(Destin) Sounds like a genius idea to me. (Carl) [laughs] Let's do it.

(Destin) You know... This is expensive right? (Carl) Yeah

(Carl) Aah this is probably about 300 feet. Three and I'm gonna

turn the motor off right now, and we're coming in without

power. (Destin) On a very expensive helicopter. (Carl) Oh yeah. (Destin) So there's no power right now.

What did you just do? (Carl) We're turning the pitch of the blades down,

and as the helicopter is falling down, the air being forced through by gravity

spins the blades. (Destin) So it's like a windmill? (Carl) It's like a windmill. (Destin) So helicopters are

a whole lot safer than I thought. I'm gonna be honest with you I'm not very impressed though cause

it was right side up the whole time. [laughs]

(Carl) Let's do it upside down. (Destin) W..w..wait dude. I'm joking dude.

(Carl) Aah. Let's do it! (Destin) He can do it. (Carl) Let's do it!

I am not responsible for what's about to happen.

(Destin) Are you upside down already? (Carl) Oh yeah.

(Carl) Here we go. We're gonna flip upside down.

(Destin) So you have an unpowered.. (Carl) Power is off (Destin) helicoper upside down. (Carl) Correct.

(Destin) This makes perfect sense. Holy cow.

(Carl) There we go. (Destin) That is messed up man. Alright so helicopters are

a whole lot safer than I thought, and if you want to see more about how they work

look at this video series that we're making, how to control helicopters. This is Carl.

I put his info in the description. Please subscribe. Later. Where's my thinking hat?

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