Smarter Every Day/YouTube

WATCH: Guy straps himself into a falling helicopter to prove they don't drop like bricks

All to prove Neil deGrasse Tyson wrong.

FIONA MACDONALD
27 APR 2016
 

There aren't many people who'd strap themselves into a plummeting helicopter voluntarily, but apparently when you really, really love science, you've got to do whatever it takes to demonstrate the laws of physics.

Or, at least, that's Destin's excuse over at YouTube channel Smarter Every Day, as he puts his life on the line all to prove Neil deGrasse Tyson wrong.

 

The whole experiment was inspired by a tweet from deGrasse Tyson about how helicopters fall:

For those of you who aren't familiar with Smarter Every Day, Destin just happens to be something of an expert on helicopters, and he was pretty sure this wasn't true - helicopters don't just drop like bricks.

In fact, he was so confident about it that he was willing to get into a helicopter and cut the engine mid-air, just to prove that it would glide, thanks to a technique known as autorotation.

We don't want to give away the ending here, but as you might have guessed by the fact that Destin lived to upload this video, he was right.

The whole experiment is a seriously beautiful demonstration of science, and while the scenery over Widgeon Lake in British Columbia is stunning, the physics is the real show-stopper.

So how exactly does a helicopter - which isn't the most aerodynamic-looking thing - glide once the engine's cut? To be fair, if the blades did just stop turning, as they do when the engine fails, the helicopter would drop like a brick, so deGrasse Tyson kind of has a point.

But helicopter pilots use physics to stop that from happening, which is where autorotation comes in. When the engine is running and the blades are turning as they should be, they work like a big fan, blowing down air and keeping the helicopter hovering, Destin explains.

If the engine stops, the helicopter starts to fall, and this changes the direction the air blows through the rotors. But just like a powered fan can create air movement, air movement can also create fan movement, like it does with a spinning pin wheel - those fun colourful things you blow into at carnivals to make them spin around.

Screen Shot 2016-04-27 at 5.31.02 pmSmarter Every Day/YouTube

So what pilots need to do is change the pitch of their blades, using a control known as the collective, to angle them in just the right way so that they keep spinning as the helicopter gradually falls. This brings the craft slowly and gently in to land, effectively changing the blades from a fan to a pinwheel.

It's not quite as easy as it sounds, because if you change the pitch too fast, you can overspeed the rotors and break stuff (hello, falling brick), but with some subtle easing on and off of the collective, pilots can have a surprising amount of control over their falling aircraft, as Destin proves by literally strapping himself into a powered-down 'copter.

You need to see the drop in action in the episode above to understand just how cool this is, and to appreciate the physics at play - and you also really don't want to miss out on deGrasse Tyson's video response when he gets debunked.

All's fair in love and science.

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