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Airplanes are one of the quickest ways to get anywhere, but commercial jets haven't gotten much fast since the 1950's. Why is that?

Hosted by: Hank Green

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Hank Green: Commerical jets are amazingly convenient and super fast, but if you look at their history, you will notice something a little bit weird. The first passenger jet, called the de Havilland Comet, entered commercial service in 1952 and flew at about 740 kilometers per hour. Next came the Soviet Union's Tupolev Tu-104, which maxed out at about 950 kilometers per hour. And then there was the Boeing 707 in 1958, which had a top speed of 965 kilometers per hour. Which, for the record, is about the same speed as commercial jets flying today. So what gives? Why have passenger jets been stuck at this speed for more than 60 years? I want to go places faster!

Well, if you're looking for somebody to blame, and I am, don't point your fingers at the engineers. You can instead blame air molecules. To understand this speed limit, you have to know a little bit about airplane wings. If you were to slice off the end of a wing and look at the cross-section, you would see a shape like a squished teardrop. That's called the airfoil, and it's a major part of what gives planes lift. As the plane moves forward, air travels under and over the wing, and the teardrop shape creates two distinct regions: an area of high pressure air below the wing, and one of low pressure air above it. Ultimately, the high pressure air ends up pushing upward, which pushes on the wing and keeps you chilling in the sky eating that free bag of slightly stale pretzels.

But lift isn't the most important thing in this conversation. After all, while this is happening, the plane also is hurtling forward at hundreds of kilometers per hour. That means air isn't just sitting around in these high and low pressure bubbles, it's flowing over the wings at an incredibly high speed.