Flying Saucers (?)

Probably painted circles like the one in-line with these two just to the left of the sheds.

Google Earth shows this area, West of the Pratt Witney facility, as being part of Sikorsky West Palm. In some of the views via MSN Live Local-Birds Eye, one can see a helicopter parked out front. I believe the circles on the tarmac are to show the blade paths of the helicopters centered in them. I think, as the previous commenter pointed out that they have similar circles in the hangers for centering of the parked helicopters and to mark where the blades would rotate so as not to park it where the blades could hit the walls if they were slowly turned in testing / repairs.