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ThiveInSpace

centre of mass and centre of lift behaviour with far

Question

So firstly the centre of lift it is slightly slow to refresh I'm guessing this is far doing calculations.

My main question, I am building a plane using realism overhaul and realistic progression, with FAR. I would like to my centre of lift to be above my centre of mass to utilise the pendulum affect to stabilize my craft.

My com is slightly below my col, When I raise the Wings to the top of my craft the com moves with the col. Granted the Wings have some weight I'm using procedural parts. So I emptied the Wings fuel tanks and lowered the mass strength muilplier %. Thinking this would change only the mass and not the lift, but the com and col both move down.

Why does col change when only changing weight of parts? Is it something to do with FAR indicator being centre of pressure not centre of lift?

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Posted (edited)

I don't use FAR, but that sounded strange:

45 minutes ago, ThiveInSpace said:

I would like to my centre of lift to be above my centre of mass to utilise the pendulum affect to stabilize my craft.

In flight a plane doesn't so much "hang" from its CoL, but it "falls" trough the air. If the CoL would be pure drag - i.e. there is nothing that creates torque except the relative positions of CoM and CoL - then the plane would orient itself so that the CoM is straight forward (in the direction of travel) of the CoL. So If you have the CoL not only behind but also above the CoM then it would fly with a pitch-up attitude.

Edited by AHHans

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Cheers aAHHans I see as the force vetor do's not continue pointing straight up as the plain pitches this does not create torque or a pendulum effect. Ok so I need my col level with com?

Still confused why col changes with mass of parts

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9 hours ago, ThiveInSpace said:

Ok so I need my col level with com?

You don't need to. What I wanted to say was that it doesn't help you.

In an actual plane you have more forces than just the sum of the lift applied at a single point. To fly straight and level an airplane needs to be trimmed to that speed and mass distribution, i.e. the control surfaces need to be positioned to cancel the pitch moment(s).

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