Independent and Tramp Traders

Michael Everett wrote:

Jonathan_S wrote:The operational costs per ton of cargo should drop quickly in a larger design, so economics tend to push for the largest practical freighter. (Though routes using busy wormholes might push back against that if the tolls strongly penalize ships large enough to cause delays due to destabilizing the wormhole longer than the normal transit interval between ships)

Bolding mine.

I don't think that transit intervals are a problem with civilian starships. Given how you can never be sure how good civilian pilots are (multiple star systems each with differing ideas of what "good piloting" is), the gap between transiting starships is probably two or three times the actual destabilization interval just to make sure that the idiot behind the helm has enough time to remember to hit the right button to go from Sails to Wedge before the next ship appears and runs into its stern.
Military transits are different because you can be pretty certain that the helms-people have a good clue as to what they are doing.

AIUI, the Manticore Junction doesn't let civilian pilots go through by themselves. Based on the text ev of government dispatch boats not having to link to Junction Control and how the Junction controllers not liking it, I expect the only people who can go through on their own are warships and the above mentioned diplomatic dispatch boats.

I missed that in HoS. There was something somewhere else (don't remember where) that said the grayson compensator didn't allow for bigger ships.

The question remains, how much bigger? Mathematically I can see 4 ways to to go. anyone got any other ideas?

IMO, the most logical would be the cube root of the speed. 25% faster would be 7.7% bigger. (1.25^.333=1.0772) This would make the maximum size ship 9.1M tons

Square root of the speed. 25% more speed, max size 9.5M tons.
cube root squared of the speed. 25% more speed, max size 9.9M tons
Linear, IMO least likely 25% more speed = 25% bigger =10.6M tons

munroburton wrote:

darrell wrote:Where do you get a 10MT freighter at? The biggest freigher I have ever seen in the honorvers is 8.5M tons, the same size as the largest SD.

Same goes for a "theoretical 16 mton monster" which would be the same size as a junction fort.

The grayson compensators are more efficient, meaning that they allow a faster acceleration for the same ship size. They are not more powerful, meaning that the biggest ship size you can effectively use compensators on remains 8.5M tons.

Actually, maximum size has been creeping up all along.

If you read HoS, it's pretty clear the Sphinx morphed into the Gryphon, then the Steadholder Denvenski and finally the Benjamin the Great class. There's a ~300,000 ton difference between Sphinx and BtG.

There was only a tiny difference between the BtG and the Medusa, despite the radical design differences. However, the Harrington-II is 8.8m tons, just ahead of the Invictus. That's a growth of 600,000 in 20 years.

That increase may not be entirely attributable to the Grayson compensators - the tonnage ceiling went up 1.8 million tons in about 150 years before Grayson came onto the interstellar scene. The rapid growth in that 20 years may be down to Manticore's need to build individually superior units to Haven's(the Haven-class SDs apparently only massed 7.9mt and the preceding DuQuesne class was 7.2mt).

As for a 10MT freighter, I think that one's theoretical too.

darrell wrote:The question remains, how much bigger? Mathematically I can see 4 ways to to go. anyone got any other ideas?

The formula is far more complicated than a simple direct relationship. The exact numbers have been posted a couple of times, but I don't recall them precisely. In general, acceleration curves are the same for "Grayson" vs "Pre-war" accross the entire range. Both types are effective up to about 8 MTons and then effectiveness drops off precipitously at an increasing rate.

The numbers are random, for illustration only:

4 MTons == 500G
8 MTons == 400G
8.5 MTon = 100G

At around 8.5-9.0 MTon, grav plates provide more acceleration than compensators.

For a freighter you have the rather huge issue that if the cargo hold isn't in zero g you need to secure it against acceleration.

Weird Harold wrote:

darrell wrote:The question remains, how much bigger? Mathematically I can see 4 ways to to go. anyone got any other ideas?

The formula is far more complicated than a simple direct relationship. The exact numbers have been posted a couple of times, but I don't recall them precisely. In general, acceleration curves are the same for "Grayson" vs "Pre-war" accross the entire range. Both types are effective up to about 8 MTons and then effectiveness drops off precipitously at an increasing rate.

The numbers are random, for illustration only:

4 MTons == 500G
8 MTons == 400G
8.5 MTon = 100G

At around 8.5-9.0 MTon, grav plates provide more acceleration than compensators.

I've done those spreadsheets but they don't really give a good answer.
Old style compensators hit the wall at 8.5 mtons. Past that they lost 1g for every 2500 extra tons.
New style compensators are up to about 155% the accel of the old ones. I can't be 100% sure because we almost never get compensator generations to match against the higher accel; but I appears to be a linear incease. Take the old value and multiply by 1.55 to get the new value.

However the Invictus does a or appear to be past the efficiency cliff. So the max speed see went under some. But probably not by 1.55x as that would make the new limit 13 mtons; which seems insanely high (given the modest increase in ship size.)

So best guess is that the limit went up by way less than the acceleration did. Maybe it's up to 9 or 9.25 mtons. But that's a random guess; we don't have any data.

Jonathan_S wrote:So best guess is that the limit went up by way less than the acceleration did. Maybe it's up to 9 or 9.25 mtons. But that's a random guess; we don't have any data.

Another data point missing is the size of the "inertia dump" capacity of modern wedges vs wedges at the start of the series circa 1900. We know there have been advances in that technology as well as compensator technology. How much does a more powerful drive affect the acceleration permissible by the compensator.

We do know that a more powerful drive doesn't always equate to better compensator performance because of the Mars class from Haven. We also know that the near-infinite capacity of a grav-wave allows for much higher acceleration. In Theory, a stronger wedge would also allow better compensator performance.

kzt wrote:For a freighter you have the rather huge issue that if the cargo hold isn't in zero g you need to secure it against acceleration.

You are going to have to secure the cargo in any case. There is no way you are going to just pile cargo containers up in the holds of a freighter. Even if the hold is in zero g (no compensators or gav plates) when you move the ship you really need to make sure that the cargo doesn't shift. Picture a half full bottle of chemicals from an experiment left hanging in the International Space Station as the crew person working on it will need it for the next step. "Something" comes up and the crew have to do an emergency burn to move the station "forward". The station moves, the bottle doesn't until the back wall of the compartment slams into the bottle.

Freighters (and naval vessels) on water need to secure cargo from shifting. Rough weather, turning particulary high speed turning, etc. Box cars for trains (and shipping containers on trains) need to have cargo secured against shifting. Trailers for over the road trucks need to secure cargo against shifting.
You have to figure out where you are putting what in your load both for balance (even distribution of weight). I would guess that weight distribution (or mass distribution) is going to be just as important on a hyper-capable space ship as it is on an ocean going freighter. I will also guess that trying to compensate for an unbalance load on a starship is going to be just as costly and tough on the equipment as it is on a cargo ship though perhaps lacking the danger of capsizing.

You also need to work out the anticipated order of what you will need to get on and off the ship etc in what order so you don't have to handle any segment of the cargo more than you have to--load once, take off once (and don't shift it around between times) is the ideal.

Brigade XO wrote:

kzt wrote:For a freighter you have the rather huge issue that if the cargo hold isn't in zero g you need to secure it against acceleration.

You are going to have to secure the cargo in any case.

snip

The question is how it would be secured. In another SF series, there was mention of an anti-crash protective field for pilots, don't remember such in the HH series. I wonder if something like tractor or pressor beams, but suppressing relative motion instead of causing it would make sense here.

Securing 20 million tons of steel girders against 5cm/sec^2 maneuvering of a docking thruster is not at all like securing 20 million tons of steel girders against the 500m/sec^2 of 50 gravities of a wedge.

kzt wrote:Securing 20 million tons of steel girders against 5cm/sec^2 maneuvering of a docking thruster is not at all like securing 20 million tons of steel girders against the 500m/sec^2 of 50 gravities of a wedge.

50 gravities is soakable by standard grav plating, I'm pretty sure.
Even without that, as long as the inertial compensator is functional, any wedge-based acceleration is meaningless, and the effects of maneuvering thrusters can be handled by the grav plating. And if your compensator isn't functioning properly, you're going to keep to the accel your plating can handle while on your way to the nearest place to repair or replace your compensator.

That being said, you'd still need to do some degree of securing the cargo, as you want it to be organized on loading and remain organized while off-loading, and accidents can happen. Much of that would probably be handled through some degree of automation, though.