Re: Giant Frisbee at TNMOC
That looks like the platter from the large disk drive made IIRC by CDC and rebadged by other mainframe companies in the late 1960s and early 1970s..
The 600MByte (yes - megabyte) drive consisted of two side by side vertical stacks of several of those platters. The head positioning actuator was positioned in between them. It was so large that both heads moved the same distance in opposite directions simultaneously to neutralise the forces.
The disk bearings were water cooled. If the mains pressure dropped then the unit would start to shut down - which allowed the water pressure to rise above the threshold. The result was a regular loud groaning sound on those occasions
The whole thing was in an enormous cabinet about 1m (d) 2m (l) 2m (h) and weighed 1.5 ton(ne)s. It had mostly transparent sides so you could see it operating.
When it was installed it was squeezed through the building's access doors and wheeled down the computer room along a central aisle that was solid concrete underneath the tiles. As it was moved off the aisle the false floor started to collapse. Luckily they managed to retrieve it until the floor was strengthened - otherwise it would have meant taking the roof off the building for crane access.
Initially we had regular problems with head crashes - which would carve a bright silver band about 2cm wide round the platter. There appeared to be only one engineer in the company (country? world?) who could set them up reliably.