What limits the altitude at which a jet engine may fly? What could happen if you flew too high?

Answer 1

Simply, how much oxygen does the engine require to burn the fuel in it's combustion chamber. Different engines are designed for different things; The B52's J58 engine, for example is also used in other planes - including the U2. The engine can remain burning at extremely high altitudes, but there are different versions of the same engine to handle the lower pressure where the U2 operates versus where the B52 is designed to fly.

I had an airline pilot friend who was ferrying a 727 back to Dallas years ago, and the three of them were trying to set the 727's altitude record; It wasn't the engines that had the problem - the wings were too stubby to support the plane much higher than 42,000 feet. He said, "We'd be flying along, and one wing or the other would start to dip - we couldn't fly too fast, because the airstream would become supersonic over the wing, so... every now & then, we'd just FALL out of the sky..."

Chuck Yeager flew a modified Starfighter - an F104 - designed to operate at extremely high altitude. It's engine was *expected* to quit - and it did. The plane was equipped with reaction control thrusters for manuevering at altitudes above 100,000 feet, and when the plane fell down to altitudes that would support a re-start, he turned the engine back on. In "The Right Stuff", they show him as losing control & bailing out of that plane, but I read the movie took some liberties with the real story.

Answer 2

The limit is lack of air. The air gets thinner gradually with altitude. If an engine gets too high then it would quit running, for lack of air. Pilots call it a flame out. Of course lack of air also makes the wings loose lift, so usually the plane cannot go high enough to flame out because the wings loose lift first. The plane just climbs more and more slowly the higher it gets until you reach an altitude where any attempt to climb more results in a stall, where the wings loose lift and cause the plane to decend into denser air. By the way, there is a special section for aircraft questions, and this is not it. See the source.

Answer 3

A jet engine is simply an engine that ejects high-velocity fluid in one direction order to propel an object in the opposite direction (Newton). The rockets used on spacecraft are still jet engines.
If you mean air-breathing jet engines, then enough air needs to be available for the compressor to use. These jets would simply fail to burn at high altitudes.

Answer 4

You need air to burn jet fuel, 100,000 feet is high enough.