Captain Jonah said:
Given that one of their worlds ran to 100,000,000,000 population and was so dependent on outside supply that half the population died of hunger when the Empire fell which I suspect means 100,000Dton plus mega freighters just to carry that much food plus they were flying fleets of 50,000Dton warships they were the 3rd Imperium on a small scale.
Let's see. Use http://en.wikipedia.org/wiki/Humanitarian_daily_ration as a baseline.
Says it contains 2200 calories, as well as a few accessories, but no heater. 850 grams of mass, volume unlisted. Google search says they are 3x5x9 inches or 0.00221225 cubic meters. A Traveller dTon of 13.5 cubic meters can thus hold just over 6100 such rations, let's call it 6000 to account for packaging containers and so on.
That's 16.43 man-years of food. Assuming 100 billion people, a cargo volume of 6,097,560,975 dtons is needed to transport food for a year.
That of course assumes no domestic production of food at all. Let's halve it, because you said only half the population starved (probably a simplistic assumption, but it'll do). Round it down to 3 billion dtons shipping capacity per year.
Assume a round trip takes 4 weeks (one week to load/prep, one week jump, one week to unload, another week to jump back) means each ship can do 12 trips per year. So we need ships with a total cargo capacity of 250,000,000 dtons.
I am not well-versed in OTU, not to the point of knowing who the Sindalian empire was, but unless I misplaced a lot of decimals here (which won't surprise me), they were clearly an economic powerhouse.