Flying Beer Cans

de Havilland Comet

Ever notice how solid feeling a 2 liter plastic soda bottle feels before it is opened? It is like rock hard. That is because of the internal air pressure. After it has been opened and the pressure has been released it is much more malleable.

Once upon a time I read that the aluminum skin of a jet airliner is proportionally thinner than that of an aluminum beer can, and you know how fragile an empty beer can is. Doesn't bode well for the airliner.

Yesterday I was reading about aircraft and I came across a bit about the ill-fated de Havilland Comet, the first jet airliner. Two of them crashed. Eventually they figured out it was because of metal fatigue around the square windows. The planes would be pressurized when flying, and then when they landed, the pressure would be equalized. This caused the metal to flex, and around the windows it flexed too much and it started cracking, and that's all it took. The cracking led to failure which led to the window being blown out which led to explosive decompression.

So I just realized that a jet airliner flying at 40,000 feet is going to be a lot like that brand-new, never before opened, two liter soda bottle. Rigid as a board.

But what about that Boeing plane that had the skin ripped off the top of the passenger compartment over Hawaii? They were not quite as high (24,000 feet), so the pressure differential wouldn't have as high. Or maybe it wasn't metal fatique at all that brought down the Comets. Maybe it was a terrorist plot...

I chose this picture because it clearly shows the intakes for the jet engines embedded in the leading edge of the wing. I don't think any jet aircraft, except for fighters, has done that since.

Update June 2015: Replaced the photo that Blogger lost.