  Aims: We study the acceleration of the stellar winds of rapidly rotating low
mass stars and the transition between the slow magnetic rotator and fast
magnetic rotator regimes. We aim to understand the properties of stellar winds
in the fast magnetic rotator regime and the effects of magneto-centrifugal
forces on wind speeds and mass loss rates.
  Methods: We extend the solar wind model of Johnstone et al. (2015b) to 1D
magnetohydrodynamic (MHD) simulations of the winds of rotating stars. We test
two assumptions for how to scale the wind temperature to other stars and assume
the mass loss rate scales as Mdot ~ Rstar^2 OmegaStar^1.33 Mstar^-3.36, in the
unsaturated regime, as estimated by Johnstone et al. (2015a).
  Results: For 1.0 Msun stars, the winds can be accelerated to several thousand
km/s, and the effects of magneto-centrifugal forces are much weaker for lower
mass stars. We find that the different assumptions for how to scale the wind
temperature to other stars lead to significantly different mass loss rates for
the rapid rotators. If we assume a constant temperature, the mass loss rates of
solar mass stars do not saturate at rapid rotation, which we show to be
inconsistent with observed rotational evolution. If we assume the wind
temperatures scale positively with rotation, the mass loss rates are only
influenced significantly at rotation rates above 75 OmegaSun. We suggest that
models with increasing wind speed for more rapid rotators are preferable to
those that assume a constant wind speed. If this conclusion is confirmed by
more sophisticated wind modelling. it might provide an interesting
observational constraint on the properties of stellar winds.
