Same trim settings all the time

[Mareckis]

Hi all,

I did quite a few flights with IXEG 737 in different configurations ( weights, fuel ), however what i`ve noticed id that whatever ZFW and fuel i input into FMC i always get a trim settings of 3.4.

Every single time, is that correct? Or is it something I`m doing wrong. Not sure what else to write to add more info for those that need to know. 

Greets

[Litjan]

Hi Mareckis,

the trim is only influenced by the CG (center of gravity) - not by the zero fuel weight.

You can set the center of gravity in the "ground handling" IXEG pop-out menu, or alternatively in the X-Plane weight and balance GUI.

The recommended trim setting as read in the FMS will only change if you input the correct CG there - it defaults to 20% MAC (mean aerodynamic chord, a measure for it´s longitudinal position).

You can also read the recommended trim setting in the ground handling menu, next to the CG value.

Cheers, Jan

PS: In the real plane (and also to some extent in X-Plane) the CG will shift during the flight - when people walk back and forth, and also as fuel gets burned, as the location of the fuel tanks does not coincide perfectly with the CG. The effect is pretty mild, though, and the pilot will typically not notice it.

Edited December 2, 2017 by Litjan

[Mareckis]

Hi Jan,

Thanks for a quick and clear response.

I just thought when you change the weight and fuel then CG will change accordingly ( randomly for weight distribution).

Thanks anyway, Ill play with CG next time on the ground ( flying now:) ).

 

[Litjan]

Normally (on a real plane) it would - since the bags and pax stay in position and the fuel "shifts" its position. However, we treat the CG as shown in the "ground services" menu as the CG that is currently valid. This is the way that the real pilots would interact with the CG. They don´t see it shifting during loading/fueling - they just get a "final" CG when the loadsheet arrives.

Happy landings, Jan

 

[Hullu-poika]

We need a loadsheet simulator 

I was really missing some time ago for random pax and fuel load manager and CG calculation based on it.

But finally when I played with IXEG random ZFW/CG button in the ground handling menu I have found that if aircraft is trimmed according to actual CG there is no real difference between 20% MAC or other to control the plane. At least I do not feel it.

That means in my opinion there is no really high necessity to play with different CG because it does not lead to significant changes of aircraft behaviour.

But... May be I am wrong. That is just my impression.

 

[Litjan]

Your impression is right - the pilot will not feel different CG´s as long as they are within the allowed envelope.

Cheers, Jan

 

[captain_alligator]

I remember getting ready to board a flight, the staff announced that the plane (an A319) was so empty that some of the few passengers would have to be moved to balance it up! I don't think some of them were very happy as they had frequent flyer status with the airline and weren't used to sitting behind the wing with riffraff like me. My heart bled for them... serves them right for booking all the window seats in the first few rows!