ELI5: Explain Like I'm 5

Critical Mach number

Hey there kiddo! Do you know what airplanes are? They're big machines that can fly high up in the sky, just like birds! But do you know that they have a special number called a critical mach number that helps pilots fly safely?

You see, as an airplane flies faster, it goes through the air differently. The air moves around the wings and the body of the plane, and if the plane goes too fast, it can cause something called "buffeting". That means the plane starts to shake a lot, and that's not good for the plane or the people inside it!

So to avoid that, engineers created a special number called the critical mach number. This number is basically the maximum speed that an airplane can fly without experiencing dangerous buffeting. If a pilot goes faster than that, they might lose control of the plane!

But the critical mach number is not the same for every airplane. It depends on the shape and size of the plane, as well as the altitude and temperature of the air. That's why pilots and engineers need to calculate the critical mach number for each specific airplane and the conditions it will be flying in.

So, in summary, the critical mach number is a special number that tells pilots and engineers how fast an airplane can fly without shaking too much, and it helps keep everyone safe in the sky!