centre  de gravité total
 GX GY
      0.73768     -0.34020
      0.58049     -0.26658
      0.47869     -0.30705
      0.06026     -0.34905
     -0.06919     -0.24860
     -0.10934     -0.11057
     -0.14659     -0.08747
     -0.13014      0.00343
     -0.06919      0.07449
     -0.00844      0.06427