According to the Eve item database the mass of the Hyperion is 100,200,000 kg and its volume is 513,000 m3. That means its average density is 195 kg per m3 which seems reasonable.
The problems arise when you compare length to volume.
Volume is simply length times width times height and we know the length is 1700 meters. That means the rough width times height of the Hyperion is about 301 meters squared. That number seem low to you? It should.
Basically if the Hyperion was a rectangular block 1700 meters long and a volume of 513,000 m3 then it would be about 30 meters wide and 10 meters high. In essence, a Hyperion would look like this:
That is a profile of a rectangle 30m x 10m x 1700m. More like a rod I'd say. Let's review what a Hyperion actually looks like, shall we?
Its immediately obvious that a Hyperion is vastly more than 30 meters wide and 10 meters high even at its thinnest. So either the length is wrong or the volume is wrong. Since the volume comes from Eve itself, we must question the length. What if the length was half as much, merely 850 meters? Then the profile would jump to 30 meters by 20 meters! Look at that picture again... you think it being 20 meters high is a likely possibility?
No, in order for the proportion of the Hyperion to match the volume, I'm thinking that if the length is A then the average height is about one fifth the length and I'll go with the same for width, treating it like a square. So solve for A:
A x A/5 x A/5 = 513,000
A^3/25 = 513,000
A^3 = 12,825,000
A = ~234 meters
Length of 234 meters, width of 46.8 meters, height of 46.8 meters. Roughly. Ok, maybe that is the right length then, right?
Only one problem. If the Hyperion, one of the largest battleships in the game, is 236 meters than the Rifter is correspondingly 8 meters long, the size of a fighter jet. With a Eve db volume of 27,289 m3, the length of 8 meters means its height times width value is in the range of 3411 m2 which if you think of it another way... a Rifter would be 8 meters long, 34 meters high, and 100 meters wide. Obviously that will just not work.
The point I'm trying to make is that the volumes are completely off for ships, drones, modules, ... and carrier ship maintenance arrays.
A typical carrier has a Ship Maintenance array capacity of 1,000,000 m3 which sounds big... until you realize that if you assume its 1000 meters long than its about 100 meters wide and 10 meters high. Its the Hyperion-rod all over again! Drop it down to only 500 meters long and you can bump the height up to 20 meters. And that's ignoring the fact that the model for the Hyperion would not fit in a Nyx much less a Thanatos.
Volumes for everything in Eve have practically no actual relation to reality by any stretch of the imagination. Better to call it Eve-Size-Factor and measure it in Hooligans cubed rather than meters. I know that comparing anything in a game to reality is chocked full of disaster but the simple mathematics of volume to dimensions should not be that hard manage. Simply start with a stated fact like "a Rifter is 60 meters long" and go from there to calculate the dimensions of all ships based on how many Rifter-length they are, and then CALCULATE the volumes from the approximate dimensions. Its not even a complicated calculation. Then adjust ship maintenance array capacities to match the corrected volumes.
While the Hyperion would still look like it would never fit in a mothership, at least the math would match up.