747-400D questions

[killairbus 3]

So I'm doing a flight with max ZFW and the flight plan says I'll have about 9,000kgs when I land at my destination. I decided to check what my CG would be at approach by loading 9,000kgs of fuel at the gate and the problem is with full payload, the TOCG is too forward at that fuel amount, 12.7%.

 

So my question is if this is a safety hazard to be on final approach with TOCG that forward? Is TOCG synonymous with CG in flight in the manner that, if it's too forward at take off it's too forward for all phases of the flight especially landing? 

Sorry if my wording may confuse you, I'll clarify if need be.

 

-Angelo Busato

[Dick 47]

Hi Angelo,

To answer your question: no a TOCG that is too much forward is not a problem when landing.

TOCG however is not the cg condition of the aircraft in flight, as you state, but only the cg condition of the aircraft at TO. (with the fuel at to)

 The factor that changes the cg during the flight is the burning of the  fuel in relation to the stored location of the fuel. Fuel in the center tanks will make you noseheavy and therefore if fuel is used from the center tank in flight the aircraft will become less nose heavy. If the aircraft has a tailtank it would be the opposite. Fuel in the wings normally does not change the CG a whole lot.

For the 747 in general there are 3 cg envelopes. The ZFW envelope. The CG of the aircraft in ZFW condition (=no fuel) needs to be in that envelope. Then you have a TO envelope, the CG of the aircraft with the fuel at the moment of TO needs to be within that envelope. During flight your CG will be changing depending of which tank is delivering the fuel.

Then you will have a landing CG envelope, That would be the CG of the aircraft with the remaining fuel at landing.

The envelope as mentioned  shows (mostly in a graphical way) the CG limits applicable for the related aircraft condition.

 

b rdgs / Dick

=

and please don't kill the airbus. They are also good aircraft.

 

[killairbus 3]

Thank you very much Dick! 

 

 

"and please don't kill the airbus. They are also good aircraft."

Hahaha, maybe I'll be convinced otherwise when PMDG makes one.

 

-Angelo