EASY Flight/Aerospace questions

[wzzp144]

EASY Flight/Aerospace questions!

Here is a picture of my question.

http://tinypic.com/view.php?pic=158rvt&s=7

On the left is the Altitude (ft x 10^3) scale and on the bottom is Years. In the graph as different planes at different years.

Notice from 1900-1970 the altitude the the aircraft increase. Then from 1970s -present the altitude decreases. Why does it decreaase?

These are combat planes.

 

[viscousflow]

The altitude values are actually service ceilings

Not all of them are fighters. Some of them such as the U-2 were reconnaissance aircraft, and thus the service ceiling was incredibly high to escape any air attacks by fighters, etc...

Also, a high service ceiling is not something easily attained. It is a function of engine power, efficiency, fuel burn, and a host of other factors.

There are a lot of other reasons why service ceilings would decrease, FAA regulations for instance (such as requesting airspace at certain altitudes), there are not a lot of reasons why fighters need to go to such high altitudes. I could go on forever, so I shall stop here.