Every new technology has its quirks. Especially when that technology includes spinning pieces of metal at 1000 miles per hour, as jets do. Early jet engines were unreliable and would shut down unexpectedly. But that’s better than a “failure”. In airplane mechanic parlance, a jet engine failure is when the jet physically breaks apart. If the spinning pieces of metal are stopped by the engine’s body, the failure is contained. If the jagged-pieces-of-metal-that-were-recently-fan-blades rip through the engine’s collar and go flying-through-the-air-like-banshees, that is an “uncontained engine failure”. That phrase is printable, unlike the words I would exclaim were I ever in the vicinity of one.
So, good to know, but how does it change planes? Look at the wing of a B-29: http://www2s.biglobe.ne.jp/~hikouki/gallery/b29-wing.JPG [Ed. Note: I need to figure out how to embed images] The engines are physically in the wings. This is the easiest way to build wings, and why not? (Remember: these are giant car engines, and when you’re in a car you ride much closer to one.)
The engines on the B-47 are “podded”: http://en.wikipedia.org/wiki/File:B-36_engines,_Richie.jpg That is, they’re put in their own carries (called nacelles) and set down from the wing. Why? Two reasons, one of which drove the decision more than the other (which reason is which depends on who you ask).
First, it is easier to take an engine out of a pod than out of a wing. This makes it easier and cheaper to perform maintenance on podded engines.
Second, when uncontained engine failures happen, the shards fly through air, not through wing. Consider that the B-47’s customer was the Air Force, where uncontained engine failures are sometimes precipitated by surprising bullet interactions (is that suitably euphemistic), limiting failures was an engineering win.
Jet engines have gotten more reliable, requiring less maintenance and failures are extremely rare. But podded engines are still so good an idea that every modern jetliner uses podded engines.
So, good to know, but how does it change planes? Look at the wing of a B-29: http://www2s.biglobe.ne.jp/~hikouki/gallery/b29-wing.JPG [Ed. Note: I need to figure out how to embed images] The engines are physically in the wings. This is the easiest way to build wings, and why not? (Remember: these are giant car engines, and when you’re in a car you ride much closer to one.)
The engines on the B-47 are “podded”: http://en.wikipedia.org/wiki/File:B-36_engines,_Richie.jpg That is, they’re put in their own carries (called nacelles) and set down from the wing. Why? Two reasons, one of which drove the decision more than the other (which reason is which depends on who you ask).
First, it is easier to take an engine out of a pod than out of a wing. This makes it easier and cheaper to perform maintenance on podded engines.
Second, when uncontained engine failures happen, the shards fly through air, not through wing. Consider that the B-47’s customer was the Air Force, where uncontained engine failures are sometimes precipitated by surprising bullet interactions (is that suitably euphemistic), limiting failures was an engineering win.
Jet engines have gotten more reliable, requiring less maintenance and failures are extremely rare. But podded engines are still so good an idea that every modern jetliner uses podded engines.
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