(Roy Smith) wrote:

Brian Whatcott wrote:
loaders like to place the CofG near the aft limit. Fuel and cargo
make huge invisible loads.
Still, when someone gets it wrong, you can still shuffle passengers.

I was under the impression that most big jets had a small fuel tank in
the tail, and they could pump fuel back and forth to trim the CG. Am
I mistaken?

No you're not but they use it for economy...most a/c are built to
be quite nose heavy so they need quite a lot of nose up trim in
level flight, this increases the 'fore and aft stability'.

It's done with the moveable horizontal stabilizer and creates a
considerable amount of drag. Long range a/c (used to at least)
pump fuel back to the tail tank to replace the 'down force'
needed thus removing that drag...this removes the fore/aft
stability and mandates the use of autopilot (I think)
--

-Gord.
(use gordon in email)