Friday, January 16, 2009

Blame Canada/Pimpin' Ain't Easy

I didn't hear about the Airbus A320 emergency landing until I got home after work yesterday afternoon (about 6:00ish); as an aside, it wasn't a crash, it wasn't a crash landing - the word "crash" is constantly being used to sensationalize what actually happened. I'm not an aeronautical engineer, I'm a mechanical engineer, but I did study flight mechanics and aerodynamics with some enthusiasm and I can attest the quality of the pilot - he's a pimp.

I don't know how to fly a plane, but I know how planes fly. The wings generate lift via a pressure differential that occurs when air flows over the wing at a specific speed. Speed must be kept above a certain number, called the stall speed, or you drop in an ungraceful manner. The stall speed is an equation:

The velocity you have to be traveling above in order to fly depends on (a) the weight of the plane, (b) the density of the air (changes with altitude), (c) the area of the wing(s), and the shape of the wing. The pilot can add thrust by throttling the engines and change the shape of the wing (thereby changing CL (coefficient of lift) to keep the plane above this speed. Remember, planes don’t stall – wings stall.

Now here’s why the pilot is a pimp. He had no way to add thrust, because terrorist Canadian geese attacked the plane’s engines. In order to land (on water or land) the nose of the plane has to be kept up and the only way to do that is generate lift, and the only way to generate lift is to keep the plane above the stall speed of the wings. And this dude had no engines. How did he do it? He controlled the speed at which the plane dropped out of the sky by changing the shape of the wings (while minimizing the drag on the wings, because the more lift the wing generates, the more drag you induce and the faster you have to go). The wings shape can be changed by moving the flaps up and down; if a goose happened to damage the hydraulics that control the flaps, everybody would just be tits up today and the pilot would be blamed for 150 deaths because he couldn’t avoid a goddamned flock of geese. But the hydraulics held and this guy’s pimptasticness is now well established. Him having a mustache could have only helped the situation.

Oh, yeah… He also had to keep the speed high enough to generate lift, yet low enough not to rip the plane apart on landing. That part was mostly skill with a little luck mixed in.