Checking and shifting COM

[splashboom]

Is there a way to check the center of mass in flight? As much as I try to balance the fuel and set drain priorities I occasionally end up stalling on reentry. (My recovery rate from that is not very high) When it happens I cant keep the nose down, and pretty sure it is because the tail became heavy.

 

Thanks!

[18Watt]

I turn off SAS, and see which way the nose moves.  If it moves up, that is not good, and you need to move the CG forward.  Which I do by moving fuel forward.

If the nose drops slightly, the CG is probably close to where it needs to be.

If the nose drops a lot, the CG might be too far forward.

If the nose doesn’t move at all, the plane is just barely stable in the attitude you are currently in.  Any deviation is likely to cause instability, so you probably need to move the CG forward in that case.

Oh, here’s another trick you can try-  Normally the external camera will be centered on a vessel’s COM.  (Unless you have clicked ‘Aim Camera’ at a part..).  That’s not exact, and is not super useful unless you have markers along the side of the craft to help you know where the COM should be.

[HansAcker]

Mods or no mods?
Unmodded, I use what 18Watt describes. Zoom in and look where the camera's center point is.

With mods, MechJeb has an option to display CoM and other indicators in flight (in the "Attitude Adjustment" window).

A mod to test CoM movement in the editor is Fill It Up:

 

[splashboom]

I was going to say no mods, but I have MechJeb already. I am using about 20% of it, should have explored it a little

[18Watt]

7 hours ago, HansAcker said:

With mods, MechJeb has an option to display CoM and other indicators in flight (in the "Attitude Adjustment" window).

That is awesome.  

3 hours ago, splashboom said:

I was going to say no mods, but I have MechJeb already.

The MJ tool @HansAcker suggested looks interesting.  I’m curious how it ends up working for you, maybe report back here after you get a chance to try it out.