Thrust: Propellers


Learn how propellers generate thrust. 


Hi, my name is Jamila, I'm an Explainer at the National Air and Space Museum's "How Things Fly" gallery, and today I'm going to be talking to you about thrust.

I'm standing in front of the Hughes H-1 airplane. This airplane was designed by Howard Hughes and in 1935 it set a world record at the time for being the first plane to fly at speeds of up to 350 miles per hour.

[Jamila pulls out a small stick with two propeller blades attached perpendicularly to the tip, similar to a pin wheel]

Now, what I have here, is called a propeller. A propeller is a form of thrust. Let's see how it works.

[Jamila quickly rubs the stick between her hands, such that the two propeller blades at the top spin rapidly, causing the stick to take off, lifting out of her hands]

We made that propeller fly out of my hands and into the air. It's all based on how a propeller is shaped.

If we look again at the Hughes H-1 airplane, we see that a propeller is like a wing with the twist. Their blades can be twisted at different angles. So that when the propeller or the blades of a propeller begins to rotate there's going to be faster moving air in front of it and slow moving air behind it. 

According to Bernoulli's Principle, faster moving air is a lower air pressure while slower moving air is a higher air pressure. So again when they rotate that higher air pressure will give it a push from behind or thrust forward and that's how a propeller generates thrust.

Categories: Propulsion Propellers