can vector flow scales be set independent?

I produce a plot of a 3D vector field, u,v,w components defined on a x,y,z grid. I have defined for each component a flow control:

   flow_controlU = (FlowControl)uMap.getControl();
   flow_controlV = (FlowControl)vMap.getControl();
   flow_controlW = (FlowControl)wMap.getControl();

and I have tried to set the scale of each component with:

   flow_controlU.setFlowScale(vUScale);
   flow_controlV.setFlowScale(vVScale);
   flow_controlW.setFlowScale(vWScale);

The display acts as if only the last call to setFlowScale actually changes the vector scale and it changes it all three components.So does VisAD allow independent flowscales? Thanks!

JO