"Gord Beaman" wrote in message
...
"Leadfoot" wrote:


"Gord Beaman" wrote in message
.. .
"Leadfoot" wrote:


"Gord Beaman" wrote in message
news "Leadfoot" wrote:


For 747-100, -200, -300 yes. For the -400 it was an option many
airlines
chose. Remember the 747-400 was designed for long-range flight
with
the
winglets, the FMS and the wet tail



Speaking of which...anyone any idea of how much this feature
actually saves? (wet tail system I mean).

The wet tail carried almost the same amount of fuel as a 737. It is
simply
additional fuel to be sused and generally it is the first tank to
empty



Oh...you don't use it to increase economy by replacing flying
tail trim with fuel weight?

There is already a half ton of DU located in the tail for weight and
balance



I'm not talking about 'static balance', I'm talking about
'dynamic balance'. Some large airliners replace the normal
aerodynamic 'nose up trim' of the empennage with fuel weight to
increase economy during cruise operation only. This drastically
reduces the fore and aft stability of course and makes use of an
autopilot mandatory. Are you saying that that system is not used
on the these 747's?

It's been a long time since I worked on a 747-400. It was explained to me
that the fuel in the tail was used first. It may still be that way or they
could have changed it since I left Boeing.

I'm not a pilot Just an avioncs tech who has left the industry due to a
busted knee


--

-Gord.