Max Service ceiling for commercial airplanes

Morgans writes:

What percentage of power are the engines normally running, on the "coming
down" portion of a flight like that?

Flight idle.

Mxsmanic wrote in
:

Morgans writes:

What percentage of power are the engines normally running, on the
"coming down" portion of a flight like that?

Flight idle.


And what's that, wannabe boi?

Bertie

Mxsmanic wrote in
:

writes:

Out of curiosity I was wondering which civilian passenger airplanes
have the highest service ceilings? Wikipedia indicates that some
business jets have ceilings greater than 53000 ft or so while the 747
has only 43000 ft. Also why do large aircraft fly much lower than
their service ceilings?

One important reason is restrictions on the time within which they
must return to an altitude that doesn't require pressurization in the
event of a sudden loss of cabin pressure. They have to be able to get
to that safe altitude within a certain number of minutes without
overspeeding the aircraft.

Also, the higher the altitude at cruise, the greater the pressure
differential in the pressurization cycle, and the greater the wear and
tear on the airframe in consequence. Pressurization cycles are one of
the limiting factors on airframe lifetimes.


No a factor in limiting the altitude, fjuktard.

Bertie

Ricky wrote in news:d853bc93-6705-4f74-bc06-
:


I remember learning recently in A&P school that 36,000 ft. is the
optimum altitude for long-range cruising. At approx 36,000 the temp.
stops falling & remains constant but pressure still decreases
resulting in a rate-of-thrust decrease that's more rapid at higher
altitudes than approx. 36,000.


Hmmm, it is true that the temp stops decreasing around there. (It's called
the Tropopause) but i never thought of it in terms of thrust like that
before. Rate of climb does get a little iffy up that high!


Bertie