Use the forcepanel, which is a free add-on to Fluent 12. After reading the scheme you will get an entry in Reports/Resultant Force. You can write out lift, drag, coordinates of CG, force, moment vs iteration or vs flow-time in a separate file. Enable "moving body coordinate system" and the "print to file". Now open the dynamic mesh panel, and confirm the moving zone with "create". This ensures that the force panel recognices the zone motion. In the force panel click on "update" and "print". If you start the simulation now, an external file will track the quantities.