I'm using the averages here. . .
Take a look at the list of vehicles here and divide the number of vehicles on the around 15 US divisions fielded:
hxxp: en. wikipedia. org/wiki/List_of_currently_active_United_States_military_land_vehicles
Trying to average the number of Abrams tanks in the entire US military is not going to tell you how many tanks are in a heavy armored division, because the heavy armored divisions are not the only divisions that use them. The marines also use them. Infantry divisions use them as well, just in fewer numbers. If you look at the actual heavy armored divisions, they use between 100 and 250.
Please don't claim I am wrong when it's clear you didn't even bother to check the numbers for your own claim yourself.
A single prime mover (truck) would take up a volume of 2. 5*5*25 = 312. 5m^3 volume or 110 tonnage (GRT) volume. That's far more then its empty weight in tons. Is it less for a tank? Yes around half volume GRT, but most vehicles are not tanks and would be about equal in GRT and tons being somewhere between a tank and a truck in density.
It doesn't matter if you use volume or weight, a modern mechanized division will take up loads of both to move.
I did check. I checked your numbers on the tanks and they were pretty obviously using weight instead of tonnage. The rest didn't matter for reasons I got to later.
Also I am not sure what truck dimensions you are using, but the US army's most common transport is the M35 which has dimensions of 2. 4m*2. 8m*7. 0m, which is only 10. 979 Gross Tonnage (from 47. 04m^3). You chose to use GRT, which is awkward because a) it is extremely complicated to determine the fill space of a truck, and b) it's not really used anymore. I doubt very much Steve is using GRT for his tonnage scales. I ran through the formula for a truck of the size you described, just for the sake of it, and you're looking at 76. 5 GT. Which is still significant, except that the truck itself is comprised mostly of storage space and would themselves likely be carrying the majority - if not all - of the supplies required by the division. Ie, they would not unload the trucks.
Just for the record, I checked the GT of an Abrams tank and it's only 17. 6. I used the hull dimensions (rounded up) because the gun doesn't prevent the tanks from lining up (the gun can occupy the space of the tank in front of it, so only the hulls actually determine tonnage). So yeah, not that much.
Your failing to account for that to carry stuff you need a container around it and an ability to drive it on-off like ramps and some clearance.
To carry heavy stuff in space you need really heavy containers and heavy duty ramps.
Also we have not even started on how much crew accommodation space 15'000 soldiers in aurora would need, we are talking about transporting them for months here, aurora even displays how many ton per man you need.
I am not neglecting those things. I by no means feel that the tonnage represented should be accounted for ton by ton. Half of the module tonnage, however, is a silly amount to set aside for things other than cargo capacity. Fortunately, as I said, this turned out to not be the case.
We also only talked about the weight/volume of vehicles, nothing about weight/volume of supplies (for months) and ammo (which a normal artillery piece can consume tons of in a single day of combat).
The majority of which can occupy the same tonnage as the cargo trucks. So while they would technically increase the weight, in terms of space required (which is what tonnage is), it's a non-issue.
Ok, then I am going to argue that the size of a low tech tank division is certainly far too low.
For infantry without much vehicle or heavy gun support those numbers might work.
It might be low if Steve is using GRT. I doubt he is, because it would be impossible to calculate for everything, he'd just be making up numbers. GRT is not widely used and is best at determining the space occupied by grain and other materials which 'fill' an area. The GRT of a ship for purposes of transporting grain is different from the GRT of a ship for purpose of transporting crates, for example. In this case, the GRT for transporting people, trucks, tanks, crate cargo, are all different, so which one is Steve using? He's probably not using GRT at all. At least with GT you can get a consistent measure. In either case, though, go for it. I think you're wrong, though.
Can we not forget that A. Tonnage in this does not necessarily correspond to actual weight or volume, since it affects the speed, but it also affects the size of shipyard necessary, and it isn't seperate measurements? B. That a good deal of that tonnage is going to support personnel, integration with the rest of the ship, infrastructure within the module itself, etc. ? And C. If I remember correctly, Aurora Brigades are supposedly 500 men, but it's also really fancy and high-tech equipment like, presumably, power armor and things of that nature. Meaning it's barely 5 tons per man, and for their support personnel, equipment, and vehicles.
What do you mean by 'tonnage in this?'
Tonnage is what it is. In real life ships and trucks are impacted by the weight of their cargo as well, it just has nothing to do with tonnage. Tonnage tells you how much 'stuff' you can fit into a volume of cargo space. The mass of the cargo doesn't impact that at all. It does impact speed, but that's irrelevant to whether or not a lot of trucks and vehicles will fit into a space.
As for B, I agree. Some amount of the tonnage the module occupies would need to be dedicated to life support and other systems. But I can't imagine someone designing a module where half of the module was trying to keep the other half alive. That would be wildly inefficient. But as I noted, that isn't the case, so it's moot point.
As for C, I also agree. Though I am not sure we agree on the implication. More advanced technology would generally lead to fewer vehicles, smaller/lighter arms, and less gear in general. For example, since the development of MANPADs (shoulder-mounted AA), AA vehicles have played a smaller and smaller role in the military. AA vehicle numbers have declined substantially because a smaller, more efficient, less vulnerable option is available on the front lines. More advanced man-portable gear means fewer vehicles needed to fill that role, and far less tonnage needed to transport them. I think that becomes especially true when you are talking about transporting marines around in space ships, where vehicles may not be practical.
That said, I am not sure what Steve means by 'low tech infantry' in Aurora. Whether that is essentially modern (contemporary) military technology, or something more advanced but pre-TN technology.
