  We review our understanding of the prototype ``Propeller'' system AE Aqr and
we examine its flaring behaviour in detail. The flares are thought to arise
from collisions between high density regions in the material expelled from the
system after interaction with the rapidly rotating magnetosphere of the white
dwarf. We show calculations of the time-dependent emergent optical spectra from
the resulting hot, expanding ball of gas and derive values for the mass,
lengthscale and temperature of the material involved. We see that the fits
suggest that the secondary star in this system has reduced metal abundances and
that, counter-intuitively, the evolution of the fireballs is best modelled as
isothermal.
