SW Ursae Majoris, CU Velorum and AH Mensae: three more accreting white dwarfs unveiled?

We present IUE spectroscopy of the three cataclysmic variables SW UMa, CU Vel, and AH Men. In all three systems, a broad Lyalpha absorption profile is observed. In the two short-period dwarf novae SW UMa and CU Vel, the SWP flux is interpreted as photospheric emission from white dwarfs with effective temperatures of 16 000 K and 18 500 K, respectively, similar to the well-studied systems WZ Sge and VW Hyi. From the white dwarf temperatures derived in short period dwarf novae to date, there is no significant difference between the supposedly old, low-mass-transfer TOADs and the ``normal'' SU UMa dwarf novae. In the case of the novalike variable AH Men, the interpretation of the IUE data is not unambiguous. The SWP spectrum closely resembles that of a 19 000 K white dwarf, but this interpretation is in conflict with the distance dga150 pc which we derive from the published optical spectrum. The SWP spectrum can alternatively be explained by emission from an accretion disc with a moderate mass transfer rate ( ~ 10(-9.5) Msun yr(-1) ) seen at a low inclination ( ~ 20(deg) ). The possible contribution of the white dwarf to the observed UV flux cannot be determined quantitatively from the poor IUE spectrum, but may be as high as 50 %. Based on observations made with the International Ultraviolet Explorer, retrieved from the IUE\,FA.