Physics Question

From:         pillutla@rockdal.aud.alcatel.com (Ramesh Pillutla)
Organization: Alcatel Network Systems Inc.
Date:         08 Aug 96 12:11:46 
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Hi everyone,

here's the scenario:

How does a fully-loaded 747 maintain it's speed, altitude and engine power
settings over a long flight like LAX-SYDNEY. Fuel is constantly
being burned off which implies that the weight of the aircraft is constantly
changing. If the weight is constantly changing, isn't the center of
gravity constantly changing. Alos, is fuel burned equally from both
the port/starboard fuel tanks in the wings to avoid an imbalance ?

The law of conservation of momentum states that for a body moving with a
certain velocity, changing the mass will result in change in velocity
to conserve momentum. The intuitive conclusion is that the auto-pilot
actually adjusts the engine power settings to account for the mass
of expended fuel.

To all experts out there, I would appreciate any inputs,

Ramesh