Hi, I was wondering if there is an efficient way to determine
the aerodynamic centre of an aircraft. I set up a model of the
aircraft where drag is in the Z direction and lift is in the Y
direction. I set up a grid of coordinate systems and applied Global
Goal Torque about X at each of these coordinate systems. I was
hoping to find various values at each location and then run again
at another angle and find a pair of values that remain constant to
determine the aerodynamic centre. The initial flow simulation
however showed all values as being the same, as if they were about
the origin instead.

Is there not a way to specify torque about a point? What is the
purpose of being able to select another coordinate system in
defining the torque about X? Is my only option to set the highest
level assembly origin at only one aerodynamic centre point and run
many iterations until I find the correct point?

Note that for some reason Flow Simulation crashes when trying to
select a coordinate system at the same time as defining a global
goal for torque. I had to define the global goals first, then edit
each one after to select the coordinate system. Is this a bug?

Thanks,

Peter Ferreira

And by default the system takes the origin into account for torque calculations. be sure that the origin is well at the center of your model.