STRAPPED INTO A FALLING HELICOPTER - Smarter Every Day 154

Hey, it's me, Destin. Welcome back to Smarter Every Day. One of the reasons I absolutely love helicopters is that you can get places that you can't with any other device. So today, I'm with Bradley Friesen here in... where?

Bradley: We're, uh, right now in British Columbia, at Widgeon Lake in beautiful Pinecone Burke park.

Alright, so we're going to talk about helicopters in a way that you might not have thought of before. But first, let's do the safe landing.

Bradley: So we're coming into what we call mother nature's helipad here on Widgeon Lake.

Bradley: Right, here we go! I know, is that incredible or what?

Today on Smarter Every Day, I want to talk about a particular misconception when it comes to helicopters. A very famous, well-respected scientist recently tweeted, "That if an airplane loses an engine, it turns into a glider. But if a helicopter loses an engine, it turns into a brick." Today on Smarter Every Day, I want to question this by literally putting my life on the line. I'm going back into the helicopter, and we're gonna power down the engine and we're gonna see what happens. How do we get to earth safely?

But before we do that, let's just go and enjoy this in the helicopter, and let go meet an expert on auto rotation. Let's get Smarter Every Day.

Destin: A little birdie told me that you took interest in one of my tweets where I commented that an airplane whose engine dies lands like a glider. Whereas a helicopter whose engine dies lands like a brick. Assuming that the propeller blades aren't rotating. But now I hear that you know of a way to land a helicopter with a busted engine. Well, if so, I want to know about it. You know why? Because I want to get smarter every day. So I'll be watching.

Neil: What a super classy way of responding to somebody whining about one of your tweets on the internet. Thank you very much! And you're kind of right. If the rotor blade quits turning, you are gonna fall like a brick. But helicopter pilots have a physics trick to keep that from happening. When a helicopter engine is running, it acts like a big fan blowing down the air. If you try the fan off, it stops blowing and starts to fall, changing the direction that the air goes through the rotors. Just like a powered fan can create air movement, air movement can create fan movement, just like a pinwheel.

Helicopter pilots have the ability to precisely change the pitch of their blades by adjusting a control called Collective. By doing this, whenever the engine dies, they can quickly adjust from this powered fan mode to pinwheel mode, so that they can use that air that's now coming up to the bottom of the rotor system to keep the blades turning all the way down to the ground while they fall.

If you pinwheel this too fast, you're gonna overspeed them and break stuff, and you're gonna fall like that brick. So here's the trick: we know that the outside of the blades moves faster than the inside of the blade, right?! And we also know that drag is a function of velocity. Because of this, there's a magic point along the blade where it no longer acts like a pinwheel; it acts like a fan. The pilot can then adjust the collective and determine how much of the blade he wants to use as a pinwheel and how much he wants to use as a fan. He feathers it and rides it all the way down to the ground, keeping the rotor system at just the right speed—not too fast and not too slow. He keeps the blades running in pinwheel mode and bleeds off the extra rotational energy in the form of lift, which helps him slowly glide to the ground.

This whole maneuver is called an autorotation, and it's taught by helicopter training pilots everywhere. Now, I'd like to demonstrate an autorotation because you need to do some training, right?

Destin: Yeah, we're going to talk to who? What's the guy's name?

Neil: His name is Gerry Friesen. He actually trained me twenty-five years ago. He has around 16,000 flight hours.

Destin: Good dream!

Neil: And they say it takes 10,000 hours to become a master of something. So Gerry is a master...

Destin: And a half!

Neil: And a half! It's awesome. Alright! Let's go get Smarter Every Day with Gerry Friesen.

Destin: Are you Gerry?

Gerry: Yeah! I'm Destin. Nice to meet you. How you're doing?

Destin: If someone were to say helicopters fall like bricks, what would be your input to the common man? What would you want the normal person to know about helicopters?

Gerry: Well, I... I would like anyone to know that a helicopter glides nicely like an airplane. And the nice thing about the helicopter is that instead of an airplane where you’re forced to touchdown probably at a minimum of fifty to sixty knots, a helicopter can touchdown at... ten knots!

Destin: So even safer than an airplane?

Gerry: I would say you're safer. And the reason is...

Destin: Ok, that makes sense because in order to glide, you have to be moving through the air very fast or have a high rate of speed. But in a helicopter, you could do it almost at zero. You pick an open spot. An airplane going into that spot is gonna land at sixty and tumble.

Gerry: Right! And maybe hit a few trees. That helicopter going into that spot will descend vertically for the last few feet with no momentum whatsoever, and worst that'll happen maybe it'll just clip a tree.

Destin: That's amazing! Provided that the pilot manages the kinetic energy in its rotor system and balances it with its potential energy, in kind of balance that driving region versus the driven region of the rotor system.

Gerry: Exactly! That's amazing!

Destin: Okay, so here's what we're gonna do. We're up high and we're about to disconnect the engine from the rotor system. When we do that, we're gonna start trading our vertical potential energy for kinetic energy in the rotor system. So what Gerry's doing now is he's spinning up the rotor system, and as we go down we have a part of the rotor that's driving the rotor because wind's coming up to the bottom, and we have another part that's being driven. Now that part is providing drag.

What we're doing is, as Gerry is adjusting the collective, he is trading off the distance between the driving and the driven region of that rotor. So we're coming down, he's got it spotted up really fast, and right here at the bottom, he's gonna flare it. When it flares, it trades off that kinetic energy in the system into...

There we go! You hear that? So... we just made an autorotation. We skidded to a stop, but we are alive!

Destin: Thank you very much, really appreciated it! You're the man!

Gerry: You're welcome. How many hours do you have?

Gerry: A little over 16,000.

Destin: Is that all?

Gerry: That's all.

Destin: Maybe you'll figure out how to do this one day.

Gerry: Yeah... practice, practice!

Destin: You can know the theory behind it, but you don't really understand how you do it until you do it yourself, right?

Gerry: Yeah... exactly! It just becomes a feel thing.

I hope you enjoyed this episode of Smarter Every Day. I want to say thank you to Neil deGrasse Tyson for agreeing to be the 'foil' for this video. I also want to say thanks to Bradley Friesen for taking us up in his helicopter. He's got a really cool helicopter channel you should really check it out; his dog flies with him, it's really fun. Also, I want to say thanks to the sponsor, which is kiwicrate.com.

However, they're gonna support this video in direct response to how many people get Kiwi crates. Therefore, I'm not gonna tell you about it myself; I'm gonna let my kids do it because they're cuter and probably gonna believe them more.

Kids: You can open your crates, go for it!

Kid 1: If you support Smarter Every Day, go to kiwicrate.com/smarter, and you get this really cool crate sent to your house.

Kid 2: This is called the Thinker Crate. This has like an engineering project.

Kid 1: What is this one?

Kid 2: A biomechanical hand.

Kid 1: Over here we had this. What was this one called, buddy?

Kid 2: Koala Crate... A Koala Crate. This is for younger kids.

Kid 1: And this one is called a Doodle Crate, where you can do what?

Kid 2: Make crafts.

Kid 1: Make crafts. They're really fun. You guys enjoy them?

Kids: Yes!

Kid 1: So! Okay. So we do this at our house all the time, and we really enjoy it. So if you like to go support Smarter Every Day, go to kiwicrate.com/smarter. Get a free crate sent to your house. It's a subscription service! I think you're gonna keep it because they're awesome, and they help kids be thinkers and doers and learn a lot with their hands.

Kid 2: Do you think other kids would enjoy this?

Kid 1: Yes!

Kid 2: Really? Is daddy making you say this?

Kid 1: No!

Kids: kiwicrate.com/smarter! Every box you get goes directly to support Smarter Every Day.

Destin: Get to the chopper! Get into the chopper! There's no time! Echo!!

Kids: Echo!!

Destin: Why'd you have to say the word "Echo" to get an echo?

Kid 1: So it works! Woohoo! I'm going to explore somewhere that nobody else can get to. That's what helicopters do for ya... I drink glacier water.

Kid 2: [laugh] Did you make it?

Kid 1: I almost.

Kid 2: You were very close.

Kid 1: And I broke mine!

Kid 2: It'll be okay, give me five. Good job!