Star Wars Imperial Ships: Oversized?

There are several limits on ship designs in any universe:

• Material Strengths


• available crew


• available funds


• political will


• construction time

Crew

The available crew issue is pretty big in Star Wars... some ships have hundreds of thousands of crewbeings. (Executor is over 270,000 beings...) It's 19,000m long. That's several miles. Assuming that each individual needs some 50 cubic meters of open space and/or quarters for sanity's sake, that's only 1,400,000 cubic meters - a 112m cube - so the crew numbers are pretty low for the roughly 3 cubic kilometers (3,000,000,000 cubic meters). And even given a fleet of 500 of them, that's still under a 0.1 billion people... well within the capability of Coruscant to supply the crews for even given US current rates of volunteers for naval duty.

Structure

It has an acceleration listed as 1280 G's... 12km per second per second!

With those kinds of stresses, all known normal materials in our universe simply will fail... So it has to work by some form of drive that doesn't impose that force by direct mechanical transfer.

Once you posit drives that don't use mechanical transfer, instead imposing an area affect acceleration, size ceases to be a mechanical limitation, as long as the drive fields don't tear it apart.

Officially, star wars drives work by mechanical transfer with artificial gravity preventing turning crew into red paste on the wall...
... but meaning the ships are too large because the stresses involved are unreasonably high.

Price

The Empire can afford to waste the money by all canon sources. Not an issue.

Political Will

Obviously, the Empire has the political will.

Big ships show that, and real world autocracies are very likely to push ship designs to the larger side of what's possible. It's happened a lot in naval history (in the 1800's, plus WW I and II), so a megalomaniacal leadership like we see in Tarkin, Mott, and Palpatine would probably be prone to "A few big ships are enough to scare everyone into submission" thinking.

Construction Time

We know it took many years to build the Executor - construction times of decades are long, but not really overly exaggerated. Modular builds did not make the USS Reagan terribly fast - she took 4 years from awarding to laying the keel, another 3 years from first laying of the keel until launch, and over 2 more to be commissioned and accepted. A decade, for a ship only 333m long... And many components were in construction before the keel was actually laid down.

Discussion

By comparing to the biggest warship afloat, we have 2 indicators of her being oversized...

1) crew volume density. A Nimitz-class carrier is 6000 crew (including aviation wing) in 0.3x0.08x0.06, roughly a prism, so volume 1/2 that... about 0.00072 cubic km, or 720,000cubic meters. That's roughly 1 crewman per 60 cubic meters...
Which, even cutting by a factor of 100 for the SW level of automation, means she's under-crewed by a couple orders of magnitude.

2) material strength... the executor should snap her structure the first time she goes under power given the lack of sufficient handwavium.

Even comparing to the smaller Imperial Star Destroyers, which are described in canon as costing more than a major world's annual budget, and are 1.6km long (about 0.4 wide, and 0.1 thick, roughly a pyramid, for about 0.01 cubic km (10,000,000 cubic meters) - roughly 130 times the size of a Nimitz Class carrier, and a similar role. But they have crew and troops totalling about 45,000 people, only 8x that of a Nimitz class...

And, like the Executor, the ISD's should be bending themselves into pretzels with their 2000+ G's.

So, yes, they're unrealistically large. Not for the size alone, but for the listed performance coupled to the size, they are physically improbable given the central drives.