  A set of 66 3D hydrodynamical simulations explores how galactic stellar mass
affects three-phase, starburst-driven outflows. Simulated velocities are
compared to two basic analytic models: with (Johnson \& Axford 1971) and
without (Chevalier \& Clegg 1985) a gravitational potential. For stellar mass
$<10^{10}$ solar masses, simulated velocities match those of both analytical
models and are unaffected by the potential; above they reduce significantly as
expected from the analytic model with gravity. Gravity also affects total
outflow mass and each of the three phases differently. Outflow mass in the hot,
warm, and cold phases each scale with stellar mass as $\log M_*=$ -0.25, -0.97,
and -1.70, respectively. Thus, the commonly used Chevalier \& Clegg analytic
model should be modified to include gravity when applied to higher mass
galaxies. In particular, using M82 as the canonical galaxy to interpret
hydrodynamical simulations of starburst-driven outflows from higher mass
galaxies will underestimate the retarding effect of gravity. Using the analytic
model of Johnson \& Axford with realistic thermalization efficiency and mass
loading I find that only galaxy masses that are less than $\sim10^{11.5}$ solar
masses can outflow.
