D = 4 NO scale supergravities from D = 10 superstrings

Dimensional reductions of supergravity theories are shown to yield to specific classes of four dimensional no scale models with N=4, 2 or 1 residual supersymmetry. N=1 ''maximal'' supergravity lagrangrian, corresponding to the ''untwisted'' sector of orbifold compactification of superstrings, contains nine families and has a no scale structure based on the Kahler manifold. The quantum consistency of the resulting theories give informations on the non Kaluza-Klein (string) ''twisted'' sector