Max Service ceiling for commercial airplanes

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? Usually I never see a large jet go beyond
37000 or so even on very long haul flights. I assume they would be
even more efficient if they flew close to service ceilings on long
haul flights.

On Jan 29, 6:03*pm, wrote:
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? Usually I never see a large jet go beyond
37000 or so even on very long haul flights. I assume they would be
even more efficient if they flew close to service ceilings on long
haul flights.

Just guessing, but perhaps the smaller cabin size handles the larger
differential pressure reqiuired better than a big cabin. The extra
expense (and weight) to reinforce a large cabin (ie. heavy jet size)
may not be worth it.

I've been on commercial flights up to FL410, and (I beleive) FL430.
These were long-haul international flights.

--Dan

Dan wrote in news:de91fd98-be3f-4ccb-bef2-79e2ec0dc076
@s13g2000prd.googlegroups.com:

On Jan 29, 6:03*pm, wrote:
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? Usually I never see a large jet go beyond
37000 or so even on very long haul flights. I assume they would be
even more efficient if they flew close to service ceilings on long
haul flights.

Just guessing, but perhaps the smaller cabin size handles the larger
differential pressure reqiuired better than a big cabin. The extra
expense (and weight) to reinforce a large cabin (ie. heavy jet size)
may not be worth it.

Nah, the reason the little ones can go so high is cause nobody minds if
they do!
They're not constrained by revenue considerations and can have fighter jet
type wings and other shapes to allow good buffet margins up there. You
couldn't get a 747 up that high without buffeting it out of the sky unless
it were empty and out of gas!
The pressurisation wouldn't be able for 510 in a 747 because they woulnd't
make it any tougher than they needed to.
I can't see anyone allowing a pax airplane up above 430 anytime soon for
the simple reason a rapid blowout would kill a hefty percentage of the
people on board.
Even 430 isn't going to be pretty. Anything above 350, in fact, is going to
hurt some people pretty bad.
Until a manufacturer comes up with a technology that ensures a greater
margin of safety above 430 you won't see an airliner certified above that.


Bertie

They're not constrained by revenue considerations and can have fighter jet
type wings and other shapes to allow good buffet margins up there. You
couldn't get a 747 up that high without buffeting it out of the sky unless
it were empty and out of gas!

Is this buffeting related to slow flight? I now remember reading
somewhere, maybe in stick and rudder that large jets do not want to
risk flying very high up at a low airspeed because of the possibility
of an inadvertent stall during turbulence (not sure how much
turbulence exists at FL600 though).

wrote in
:


They're not constrained by revenue considerations and can have
fighter jet type wings and other shapes to allow good buffet margins
up there. You couldn't get a 747 up that high without buffeting it
out of the sky unless it were empty and out of gas!

Is this buffeting related to slow flight? I now remember reading
somewhere, maybe in stick and rudder that large jets do not want to
risk flying very high up at a low airspeed because of the possibility
of an inadvertent stall during turbulence (not sure how much
turbulence exists at FL600 though).


Well, actually it;s low and high. When the air going over a wing that's
traveling close to supersonic is accelerated futher by the action of the
wing, it goes supersonic over the wing. When you go too fast, max mach, you
get a loss of lift. When you go too slow, you accelerate the air over the
top of wing as well due to increased angle of attack. If you load the wing
up with weight or G (same thing as far as the wing is concerned) same thing
happens. The air buffeting from the shock wave is similar to a stall ( some
sources call it a stall) and loss of control and altitude results. Recovery
can be difficult, though not impossible. There are a number of other facors
at play here, but that's the meat of it.

Bertie

Well, actually it;s low and high. When the air going over a wing that's
traveling close to supersonic is accelerated futher by the action of the
wing, it goes supersonic over the wing. When you go too fast, max mach, you
get a loss of lift. When you go too slow, you accelerate the air over the
top of wing as well due to increased angle of attack. If you load the wing
up with weight or G (same thing as far as the wing is concerned) same thing
happens. The air buffeting from the shock wave is similar to a stall ( some
sources call it a stall) and loss of control and altitude results. Recovery
can be difficult, though not impossible. There are a number of other facors
at play here, but that's the meat of it.

Pretty cool information I must say.. thanks! I guess its a whole
different world from my puny little cessna 150

wrote in
:


They're not constrained by revenue considerations and can have
fighter jet type wings and other shapes to allow good buffet margins
up there. You couldn't get a 747 up that high without buffeting it
out of the sky unless it were empty and out of gas!

Is this buffeting related to slow flight? I now remember reading
somewhere, maybe in stick and rudder that large jets do not want to
risk flying very high up at a low airspeed because of the possibility
of an inadvertent stall during turbulence (not sure how much
turbulence exists at FL600 though).




You can google the Advisory Circular AC 61-107a and it has a pretty good
dscription of what's going on. I can't read it at the moment because my
adobe is fuxored.


Bertie

Dan wrote:

I've been on commercial flights up to FL410, and (I beleive) FL430.
These were long-haul international flights.

--Dan

I've been on a commercial flight that was at ~FL600.

Gig 601XL Builder wrote in news:13q134hrfmbhv24
@news.supernews.com:

Dan wrote:

I've been on commercial flights up to FL410, and (I beleive) FL430.
These were long-haul international flights.

--Dan

I've been on a commercial flight that was at ~FL600.


Not technically commercial since it didn't make money!

You were on a socialist flight!

Bertie

Bertie the Bunyip wrote:
Gig 601XL Builder wrote in news:13q134hrfmbhv24
@news.supernews.com:

Dan wrote:

I've been on commercial flights up to FL410, and (I beleive) FL430.
These were long-haul international flights.

--Dan
I've been on a commercial flight that was at ~FL600.


Not technically commercial since it didn't make money!

You were on a socialist flight!

Bertie


Good point.