CG position wrongly affecting cruise pitch

I have noticed that shifting the CG in flight (using the empty CG slider) will change the pitch required to maintain level flight at constant speed and altitude, when this should not happen.

Normally, the pitch should stay the same but the trim position would change accordingly.

I have tested various default aircraft (C172, A320, DA62, 747-8) and they all have the same wrong behaviour.

Here are some screenshots of the tests I did:





I don’t understand why you assume that this is wrong? These small differences make sense.

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To be honest, I hesitated before posting this one. But I will take as an argument the unreliable airspeed tables that are valid for all CG positions and only give one pitch and thrust value. And these are supposed to be very accurate.

Even if these tables are very accurate, let’s say within 0.5deg,
the differences in your screenshots are noticeable lower.

The lift required stays the same with different CGs, but the lift distribution is different.

Well yeah, but if the CG change while the trim stays the same, doesn’t that mean the pitch will change because of that?

Yes, I think you’re right and I should have thought this longer before posting.

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Correct. If the aircraft is nose heavy you have to apply more nose up trim which means that the tail has to provide more downforce/weight to keep the nose in its position.
This additional ‘weight’ needs to be offset by a higher AoA.
And that’s exactly the reason why a tail heavy aircraft flies more efficient than a nose heavy aircraft.