According to MT:RM page 81 (the only place I know about where life support is detailed in several ítems), both Grav platesand inertila compensators ar TL 10...
It can be useful to mine MegaTrav to fill out the missing CT holes, but it doesn't always work well. High Guard says you've got maneuver drives limited to 2G at TL7, 5G at TL8, and 6G at TL9+, and the power plants to power them occur at TL7, though they're big beasties. MegaTrav says maneuver drives aren't even available till TL9+; gravitic thrust systems and fusion power are likewise not available until TL9+. If you want to get to orbit in at TL 7-8 in MegaTrav, you're reduced to using
Hard Times rockets. Meanwhile, CT supplement
Traders and Gunboats is offering us a 20 dT launch at TL8, and the CT air/raft is also TL8 technology.
This is one of those instances where CT and MegaTrav don't mix well. Since there are clearly tech level discrepancies between High Guard and MegaTrav, my suggestion would be to take the High Guard G-limits as evidence of the tech at which compensators are available in
that game.
As to economics, first principal is tech level: if it's in High Guard, it's the fusion plants that dictate economics, 'cause they get smaller and cheaper at higher techs. After that, I found 2G to be the best balance between speed and cost.
Let's take a 95-ton shuttle. I assume a cheap hauler: a bridge and no computer, no purification plant, flattened sphere hull, TL15. I did not factoring in the 2dT cabin crew accommodation for long-range transport; that does make a slight difference, but not enough to really change things much on a 95 dTonner. On the other hand, if you want to play with a launch or ship's boat, you want to include that.
At 1G, cost is MCr 11.14 in quantity, 72.1 dTons available space.
At 2G, cost is MCr 13.68 in quantity, 67.45 dTons available space.
At 3G, cost is MCr 16.34 in quantity, 62.7 dTons available space.
At 4G, cost is MCr 19.76 in quantity, 57.95 dTons available space.
At 5G, cost is MCr 23.18 in quantity, 53.2 dTons available space.
At 6G, cost is MCr 26.60 in quantity, 48.45 dTons available space.
Cost is a factor because, whether a company takes a loan or pays cash, they'll be looking for the highest return on investment. However, speed - or acceleration in this case - can compensate for higher cost and lower cargo space. If you can get there twice as fast, you can make twice as many runs in the same time. However, with the turnaround factor, we know that your travel time only decreases by the square root of your acceleration - you need four times the Gs to get there twice as fast.
So:
The 2G shuttle costs 1.23 times the cost of the 1G shuttle. It delivers 93.6% as much cargo 1.4 times faster: 132% more cargo delivered in the same time. The 2G is superior to the 1G.
The 3G shuttle costs 1.47 times the cost of the 1G shuttle. It delivers 87% as much cargo 1.7 times faster: 151% more cargo delivered in the same time. Contrasted with the 2G, it costs
1.19 times the cost of the 2G shuttle and delivers 93% as much cargo 1.22 times faster:
114% more cargo delivered in the same time. The 3G is not as cost-effective as the 2G, but it's a narrow thing: you might gain an advantage by offering faster service at a slightly higher cost, especially on longer runs.
From there it goes downhill: the faster you go, the more you cost and the less space you have for cargo. 6G is not cost-effective, but it can work if speed is top priority and you can charge extra for the privilege, so a 6G express shuttle is still a workable idea.
You're wanting data on a TL8 shuttle:
At 1G, cost is MCr 17.86 in quantity, 69.3 dTons available space.
At 2G, cost is MCr 27.36 in quantity, 61.75 dTons available space.
At 3G, cost is MCr 36.86 in quantity, 54.15 dTons available space.
At 4G, cost is MCr 47.12 in quantity, 46.55 dTons available space.
At 5G, cost is MCr 57.38 in quantity, 38.95 dTons available space.
Immediately clear is that the bigger fusion plant is making a much bigger cost and space difference.
The 2G shuttle costs 1.53 times the cost of the 1G shuttle. It delivers 89.1% as much cargo 1.4 times faster: 126% more cargo delivered in the same time. The 2G is
inferior to the 1G for cost-effectiveness, delivering 1.26 times more but at 1.53 times the cost for the delivery vehicle. The 2G only starts being superior after it's recouped the initial investment - which at 27 million credits and 61 tons available space, is going to take a very, very long time. You can market speed if the market's willing to bear the added cost, that's a 22% markup on freight and ticket prices. People will like that; companies shipping a lot of cargo generally won't. So, you can run cargo in 1G's and passenger service in 2G's.
And then it gets worse from there. I wouldn't say the 3G is so much faster than the 2G that it's worth calculating the markup on that one. However, again you can go to the top-speed 5g for express transport if you've got a market willing to pay that much extra for it:
The 5G shuttle costs 3.21 times the cost of the 1G shuttle. It delivers 56.2% as much cargo 2.2 times faster: 126% more cargo delivered in the same time. If you marked up prices 2.56 times for the privilege of express transport, it would be as profitable as a 1G. Steep markup; you'd need a lot of traffic before you developed a big enough express market niche to support this kind of shuttle. More likely on the really long runs, for example where 2.2 times meant the difference between a 3-day trip and a week in space. Companies will pay the extra cost if it means their executives are spending less paid time sitting in a seat or a stateroom doing nothing. However, companies aren't going to see a point in it for their routine cargo unless it's something that, "really has to be there overnight," to borrow the ad phrase.
Of course, if someone had a TL15 shuttle flown in from Rhylanor, they'd make an absolute killing in the local market.
This was done with High Guard Shipyard 2.0. I love that program.
