-Hello, everyone.

My name is Jonathan Millard and I'm a museum educator at the Intrepid Sea, Air & Space Museum.

Today, we're going to be learning all about propellers.

So, we're talking about propellers because, at the Intrepid Sea, Air & Space Museum, we have a lot of aircraft and we have a very large aircraft carrier and these things move using propellers.

A lot of people, when they think of propellers, think of something almost like this fan because propellers are a type of fan.

So, when I turn this fan on, we can have air move and that air I feel moving towards me right now.

So, we can use these fans to give ourselves a nice breeze, but we can actually use propellers to do something pretty interesting.

Because fans can move that air around towards something, but propellers, they use the air around them to actually move.

So, we already mentioned that fans can move air around, so, let's try moving air around ourselves.

So, if we take our hand and just move it around, you might feel a lot of wind around your hand.

So, let's imagine, if we want a little less air to move around, you can actually take one finger and try spinning that around... [ Laughs ] ...and you can try, now using your whole hand to move air around.

You might notice there's a lot more air being moved around.

So, if you have a very large propeller, you can make really, really large amounts of air or, in this case, water, move.

What we have right behind me is one of Intrepid's four propellers.

Each propeller weighs about 27,000 pounds and helps Intrepid move about 30 miles per hour, which doesn't sound too fast, but when you have a ship that is 42,000 tons and is three football fields long, that's pretty impressive.

So, we have this propeller here that's able to help move Intrepid forward.

You might be asking, "How is that possible?"

So, I want you to think, if you've ever gone swimming before or if you've seen someone swim before, they might do something a little bit like this.

This is how I swim.

I don't know if I'm the greatest swimmer, but this is what I do.

And when I swim, I'm pushing water behind me.

What direction do you think I'll go if I push that water behind me?

I'm going to go forwards.

That's how propellers work.

They're pushing something backwards, so they can move forwards.

So, what we see here is a propeller that's meant to push a lot of water backwards, to help a very large ship, like Intrepid, move forwards.

So, the way that propellers work is they're moving around a fluid and that can be water or that can be air.

So, air is also a fluid.

But the interesting thing about water, it's a lot more dense than air.

There's a lot more stuff.

If you try moving your hand in air, it's a little bit easier than moving your hand in water.

Because of that, propellers are shaped a little bit differently.

So, we just looked at a propeller that can move around in water.

Let's look at a propeller that can move around in air.

Because we want to be able to accelerate and move that aircraft forward, we're going to need those propellers to spin very, very fast.

So, that is why the shape of these propellers is a little bit different from those propellers meant to move around water.

So, these propellers are going to spin a lot faster than we're going to see the propellers spinning around in water.

And you might notice the amount of rotors, or different sections within this propeller, there's only three here, when there were four in that propeller we looked at moving around in the water.

So, depending on your propeller, depending on how large your aircraft or whatever vessel that you're moving around is, you're going to see different types of propellers and different shapes, too.

So, we learned a lot about propellers today.

We saw propellers of different sizes, propellers of different shapes, propellers that can move ships, and propellers that can even move airplanes.

I want you to look at propellers that you might find in your very own home.

Look at a fan.

Take a look and see how much air it can push around when you turn it on.

Look at the shape of the blades.

Think about what was designed to help it function and do its job of moving that air around.

So, thank you all for joining us today and I hope you enjoy exploring and learning more about the world around you.