  We test the ability of Schwarzschild's orbit superposition method in
measuring the mass content, scale radius and shape of a flattened dwarf
spheroidal galaxy. Until now, most dynamical model efforts have assumed that
dwarf spheroidal galaxies and their host halos are spherical. We use an Evans
model (1993) to construct an isothermal mock galaxy whose properties somewhat
resemble those of the Sculptor dwarf spheroidal galaxy. This mock galaxy
contains flattened luminous and dark matter components, resulting in a
logarithmic profile for the global potential. We have tested how well our
Schwarzschild method could constrain the characteristic parameters of the
system for different sample sizes, and also if the functional form of the
potential was unknown. When assuming the true functional form of the potential,
the Schwarzschild modelling technique is able to provide an accurate and
precise measurement of the characteristic mass parameter of the system and
reproduces well the light distribution and the stellar kinematics of our mock
galaxy. When assuming a different functional form for the potential, such as a
flattened NFW profile, we also constrain the mass and scale radius to their
expected values. However in both cases, we find that the flattening parameter
remains largely unconstrained. This is likely because the information content
of the velocity dispersion on the geometric shape of the potential is too
small, since $\sigma$ is constant across our mock dSph. Our results using
Schwarzschild's method indicate that the mass enclosed can be derived reliably,
even if the flattening parameter is unknown, and already for samples containing
2000 line-of-sight radial velocities, such as those currently available.
Further applications of the method to more general distribution functions of
flattened systems are needed to establish how well the flattening of dSph dark
halos can be determined.
