This is not often talked about, but sometimes I do wonder, how exactly do the Eyebots lift and propel themselves? .. This might be one of the great remaining mysteries of the Fallout setting, wikia entries on the web come empty on the subject and even the original Fallout Bibles had nothing to say on this.
Alien Drones from Mothership Zeta do have 'hoverplates' under them, which presumably cancel out gravity somehow, but that is alien tech not known by humans pre-war.. I mean, if humans had this kind of tech pre-war, Sentry Bots would not need legs, cars or APCs would not need wheels or tracks, Mr Handies would not have jet engines and so forth. Surely if this kind of tech was available, it would not be wasted only on flying radio speaker bots and not put on anything else?
My theory on this is a concealed miniaturized air breathing fusion rocket engine with multiple small vectored thrust vents all around the eyebot, providing just about enough thrust to lift the eyebot via ground effect reflection, with counternoise generators and anti-acoustic materials on the airframe to cancel out most of the noise. The front grill would be the main air intake. Whole thing could be air-cooled as well, what with the constant airflow going on.
Using a fusion rocket design with nuclear fuel would also solve the power requirements problem of having to hover around a half meter wide metal sphere of a robot which cannot be very light - If this was being done with batteries/microfusion cells and concealed air fans, it would eat up lots of power and end up with very limited flight times (hour or so at most, maybe) - Hovering around an eyebot is actually much more power intensive than running around in power armor even. In game the eyebots seem to be having quite long fuel endurances, might even be years - Advanced mini-fusion reactor might be able to do this, but a conventional jet engine could not.. Does not sound too practical, yeah, but aside from supersciency antigravity alien hover tech, this is the only thing I could come up with that made any kind of sense in the Fallout setting.
Any other ideas on this, how do you think the RobCo Eyebots could fly?