747 engine takeoff power

"John R Weiss" wrote:

"Gord Beaman" wrote...

Thanks Bob, and that's quite clear, no need to scan it at all. I
just had never heard of it being done before. Seems like a
somewhat unsafe thing to be doing with a high value machine in a
highly critical phase of its flight.

Perhaps 'unsafe' isn't the correct word here, my point is that I
feel that it might be unproductive to operate the a/c closer to
it's maximum capabilities just to save some 'wear and tear' on
the engines? I'd think that you're not availing yourself of that
'extra performance' in case of an engine failure at a critical
time. I suspect that it'd take a hell of a long time to make up
what they lost in that one crash. (not even to mention the seven
crew-members)

Well, this is just an example of the reality that belies the "safety is
paramount" theory...

Yep, I agree...and further, I think they're right to do so too.
I've said this before (and gotten slapped down for it) I think
a/c are too safe now...we need to allow the safety factor to
slowly float downward until it's close to the 'safety factor plus
the financial risk factor of the automobile'. At that point the
passenger will still be much safer in an a/c than an automobile
because of the much higher financial risk factor of the aircraft.
BUT the cost for an airline ticket won't be so prohibitive that
lots of people will drive rather than fly. Or are the airlines
fully utilizing the available airspace in North America therefore
there's no opportunity to increase air traffic?


Reduced T/O thrust and non-optimum noise abatement climb
profiles have been made "standard" to put economics and politics ahead of actual
safety considerations...

There are actually some limited cases (e.g., contaminated runways, to reduce
Vmc) where reduced thrust takeoffs are "safer" than full-thrust takeoffs, but
they are the exception to the rule.


John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?
--

-Gord.
(use gordon in email)

Gord Beaman wrote

John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?

We never did the fuel thing in the B-707, but we did try
to keep as much luggage/cargo in the aft hold as possible
in order to accomplish the same thing.

Bob

Bob Moore wrote:

Gord Beaman wrote

John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?

We never did the fuel thing in the B-707, but we did try
to keep as much luggage/cargo in the aft hold as possible
in order to accomplish the same thing.

Bob

Thanks Bob...
--

-Gord.
(use gordon in email)

"Gord Beaman" wrote...

John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?

I'm a 747-400 Pilot.

Some 744s were delivered with fuel tanks in the horizontal tail. They hold
10,000 Kg. I have not flown any airplanes with them installed, so I do not know
any fuel management specifics for them.

While it may be possible to "passively" manage the CG by retaining the tail fuel
as long as possible, I don't know if this is authorized. Also, AFAIK, there is
no way to move fuel to the tail tank in flight -- once transferred down, it
stays down.

"John R Weiss" wrote:

"Gord Beaman" wrote...

John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?

I'm a 747-400 Pilot.

Some 744s were delivered with fuel tanks in the horizontal tail. They hold
10,000 Kg. I have not flown any airplanes with them installed, so I do not know
any fuel management specifics for them.

While it may be possible to "passively" manage the CG by retaining the tail fuel
as long as possible, I don't know if this is authorized. Also, AFAIK, there is
no way to move fuel to the tail tank in flight -- once transferred down, it
stays down.


It's really amazing what poor info one can gather on these ngs
isn't it?...I know for a fact that I've been told by those who
appeared to be authentic 747 aircrew that moving fuel to and from
the tail tank was used to replace aerodynamic fore and aft trim
to reduce drag on long cruise legs. Apparently this reduced the
stability so much that it could only be done with a serviceable
autopilot. And that it was only done during cruise, never for any
other phase of flight.

I understand that the basic reason for the Soviet Aeroflot
aircraft inflight breakup and crash several years ago was due to
the captain's son horsing the controls 'out of autopilot' during
this phase of flight and the subsequent violent motions prevented
recovery until some major structural failure had occurred.

Thanks for the info John, I appreciate it.
--

-Gord.
(use gordon in email)

"Gord Beaman" wrote in message
...
"John R Weiss" wrote:

"Gord Beaman" wrote...

John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?

I'm a 747-400 Pilot.

Some 744s were delivered with fuel tanks in the horizontal tail. They
hold
10,000 Kg. I have not flown any airplanes with them installed, so I do
not know
any fuel management specifics for them.

While it may be possible to "passively" manage the CG by retaining the
tail fuel
as long as possible, I don't know if this is authorized. Also, AFAIK,
there is
no way to move fuel to the tail tank in flight -- once transferred down,
it
stays down.


It's really amazing what poor info one can gather on these ngs
isn't it?...I know for a fact that I've been told by those who
appeared to be authentic 747 aircrew that moving fuel to and from
the tail tank was used to replace aerodynamic fore and aft trim
to reduce drag on long cruise legs. Apparently this reduced the
stability so much that it could only be done with a serviceable
autopilot. And that it was only done during cruise, never for any
other phase of flight.

I understand that the basic reason for the Soviet Aeroflot
aircraft inflight breakup and crash several years ago was due to
the captain's son horsing the controls 'out of autopilot' during
this phase of flight and the subsequent violent motions prevented
recovery until some major structural failure had occurred.


Well yes but the aircraft concerned was not a 747
it was an Airbus A310

http://aviation-safety.net/database/1994/940323-0.htm

Keith

"Keith Willshaw" wrote:


"Gord Beaman" wrote in message
.. .
"John R Weiss" wrote:

"Gord Beaman" wrote...

John, I recall that you're a qualified 747 F/E or Pilot so can
you tell me whether replacing aerodynamic trim of the tailplane
with fuel weight to reduce drag during cruise is still being
done?...I never seem to hear of it anymore, also what's the
proper nomenclature for that?

I'm a 747-400 Pilot.

Some 744s were delivered with fuel tanks in the horizontal tail. They
hold
10,000 Kg. I have not flown any airplanes with them installed, so I do
not know
any fuel management specifics for them.

While it may be possible to "passively" manage the CG by retaining the
tail fuel
as long as possible, I don't know if this is authorized. Also, AFAIK,
there is
no way to move fuel to the tail tank in flight -- once transferred down,
it
stays down.


It's really amazing what poor info one can gather on these ngs
isn't it?...I know for a fact that I've been told by those who
appeared to be authentic 747 aircrew that moving fuel to and from
the tail tank was used to replace aerodynamic fore and aft trim
to reduce drag on long cruise legs. Apparently this reduced the
stability so much that it could only be done with a serviceable
autopilot. And that it was only done during cruise, never for any
other phase of flight.

I understand that the basic reason for the Soviet Aeroflot
aircraft inflight breakup and crash several years ago was due to
the captain's son horsing the controls 'out of autopilot' during
this phase of flight and the subsequent violent motions prevented
recovery until some major structural failure had occurred.


Well yes but the aircraft concerned was not a 747
it was an Airbus A310

http://aviation-safety.net/database/1994/940323-0.htm

Keith



Ok...thanks Keith, in the report that I read the tail tank trim
was being used. Are you saying that the A310 doesn't use tail
fuel trim?...and are you familiar with this system?
--

-Gord.
(use gordon in email)

"Gord Beaman" wrote in message
...
"Keith Willshaw" wrote:


Well yes but the aircraft concerned was not a 747
it was an Airbus A310

http://aviation-safety.net/database/1994/940323-0.htm

Keith



Ok...thanks Keith, in the report that I read the tail tank trim
was being used. Are you saying that the A310 doesn't use tail
fuel trim?

Nope, I heard that the aircraft was out of trim but
not the details

and are you familiar with this system?

Sorry I am not

Keith