Fan Testing Round 6, Potential Fan List/Methods

[Church]

Simpliest type of FDB looks Very much like sleeve (Fig.25.1). Rotating shaft + specificly to working temps selected viscosity-wise fit lubricant .. shaft kind of climbs/lifts up on that lubricant film resulting in not touching bearing at all. But such seems to work only in vertical position, in horizontal it will work like normal sleeve bearing? Big pile of theory. Mention of complex selection of lubricant.

Of course there are other types of fluid bearings like in hard disks or other devices with other means of pumping lubricant between surfaces, but that seems not the case for fans (2nd pic in this article)?

Hmmm. Hmmm? I wonder then why i've heard many times that FDB bearing fans are as good as ball bearing in horizontal position aswell, unlike sleeve bearing fans?

EDIT
I'm kind of lost. I'd love to hear comments from some engineer with more in depth knowledge to describe main principles/differences of sleeve vs FDB into simple words. And especially i'm interested in practical results of FDB fans in horizontal mount position. I wonder also if many spec-ed fans as 'sleeve bearing' ones are in reality with hydrodinamic bearings?