Analyzed are the proton and heavy ion populations observed by the Pioneer Venus Orbiter plasma analyzer in the region downstream (11.5 Rv) of Venus. The ion energy per unit charge (E/Q) ratios for protons and heavy ions are consistent with the identification of oxygen (O+) as a prevalent constituent of the heavy ions. The speeds of the heavy ions and protons are often comparable with the number densities of the heavy ions being 1% of those of the protons. The azimuthal flow angles for the heavy ions and the protons are similar and the polar flow angles of both are usually within ¿7 1/2 ¿ of the ecliptic plane. The apparent intermittent nature of the heavy ion fluxes may be an indication that erosion of the ionosphere is taking place over a limited spatial range and that the orbit of the Pioneer Venus spacecraft is such that it does not intercept the ''layers'' of heavy ions in a continuous manner. The efficiency of the erosion process may be time variable, e.g., dependent on external ionsheath flow conditions, the state of the ionosphere. Evidence is found of a shear layer, the presence of oxygen ions of varying speeds or of other ionospheric constituents. The heavy ion observations are consistent with a viscous interaction and several other processes that have been suggested as giving rise to the removal and acceleration of ionospheric ions. The analyses reported here may be relevant to an understanding of the plasma interactions associated with comets and Mars and perhaps even with the subsonic interaction at Io and at Titan.