  We analytically calculate the scaling exponents of a two-dimensional KPZ-like
system: coherently moving incompressible polar active fluids. Using three
different renormalization group approximation schemes, we obtain values for the
``roughness" exponent $\chi$ and anisotropy exponent $\zeta$ that are extremely
near the known exact results. This implies our prediction for the previously
completely unknown dynamic exponent $z$ is quantitatively accurate.
