"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