A Funny Thing Happened on the Way to the Logistics Ship

[Condottiere]

1. An equally important use for these basic grav plates is inertial compensation; by having three sets of grav plates arranged orthogonally, it is possible to combine their pulls in any direction within their area of operation.

2. If a vehicle equipped with such a setup is aware it will suffer an acceleration, the compensators can create an equal and opposite acceleration inside it, ‘cancelling’ its apparent effects for those aboard.

 

[Arkathan]

2. If a vehicle equipped with such a setup is aware it will suffer an acceleration, the compensators can create an equal and opposite acceleration inside it, ‘cancelling’ its apparent effects for those aboard.

Vehicle. Context is important.

 

[Condottiere]

Starship operators would indicate it's for spacecraft.

Do we have any listed ground vehicles with inertial compensation?

 

[Arkathan]

I quoted you. Argue with your argument.

 

[Condottiere]

Since I'm quoting canon, I would think it's up to Mongoose to justify it, rather than needing me to act as their advocate.

If I had to interpret the Holy Text, I'd say that artificial gravity tiles don't just focus gravitational force at a right angle, but can also angle it to compensate any force created by the onboard propulsion.

 

[Terry Mixon]

Since I'm quoting canon, I would think it's up to Mongoose to justify it, rather than needing me to act as their advocate.

If I had to interpret the Holy Text, I'd say that artificial gravity tiles don't just focus gravitational force at a right angle, but can also angle it to compensate any force created by the onboard propulsion.

Maybe @Geir could add some clarity as he is familiar with the the starship rules and is writing the new Vehicle Handbook. He has a unique perspective.

 

[Condottiere]

Credited authors Adrian Tymes, Sabrina Tymes, Gabriel G. A. B. Fonseca, Robert Eaglestone.

Inertial compensation could be created through multiple ways, whether they make sense or not.

 

[Terry Mixon]

Credited authors Adrian Tymes, Sabrina Tymes, Gabriel G. A. B. Fonseca, Robert Eaglestone.

Inertial compensation could be created through multiple ways, whether they make sense or not.

Well, the maneuver drives in a ship do cover it, though grav plates might do so as well. You’ve already got the maneuver drive, so it’s covered. Having zero g in the pods is covered.

 

[Condottiere]

It's a can of worms.

It's pretty vague as to how far the field effect from the manoeuvre drive extends.

And what happens when you have multiple manoeuvre drive modules.

 

[Terry Mixon]

It's a can of worms.

It's pretty vague as to how far the field effect from the manoeuvre drive extends.

And what happens when you have multiple manoeuvre drive modules.

As I read it, it’s all cumulative. All the drive modules have a combined effect in moving the ship, and so the inertial effects are also communal. It sounds like anything attached to the ship, like pods or battle riders, are covered. How that happens isn’t explained, but the effects seem clear.

 

[phavoc]

All good points, except one quibble. The g forces are negated by the maneuver drive, not the grav plates. They can be in zero g, perhaps all locked into place for an UNREP system to move them, and be unaffected by high-G maneuvers.

I have to wonder how that would actually work. If the M-drive is emitting a field, how does that work? And that's going against previous explanations of how the M-drive works. Assuming that the M-drive emits a field (spherical? Ellipse-shaped? Projected to the rear as much as forward??), then does the field only work when the drive is active? Will it work when the drive is powered up, but 0G thrust is being provided, does it emit a field?

Another problem with that line of logic is that when the drive is offline, your cargo is now in zero-G. Loads can/will shift dramatically when under thrust, put into zero-G, and then placed under thrust again. While you CAN pack your cargo to avoid that, it requires more effort, more cost for materials, and more careful loading of your cargo for tiedowns, etc. All of these are not insurmountable issues, and when you are regularly dealing with space cargo it would become a norm for everyone involved. Though it's not without costs in both time and materials (which one can arguably state that it's all built into the costs already, so who cares??).

I like for systems to be well thought out and as seamless as possible whenever possible. I've read up on the UNREP system as its stated in the rules, though I think it's got it wrong in a number of areas. For example, refueling time frames seem rather long. NASA could pump over half-a-million gallons of hydrogen into the space shuttle tank in just a few hours. Much of pumping depends on pressure and pipe diameters, though the amount of fuel that some of these ships require greatly exceeds that of the shuttle - and generally one will install such capabilities to ensure your resupply time is minimal when underway.

 

[Arkathan]

You are welcome to check the math, but taking 5x10x10 as a Dton, and the volume of a gallon in cubic feet, and the fill rate of the space shuttle (383,000 gallons in about three hours) it takes 1.75 tons of unrep systems to match NASA.
But I am old and prone to hitting the wrong button on my calculator. And I am too lazy (disinterested once I got an answer?) to run that several times as a check.

 

[phavoc]

Roughly speaking, the space shuttle main tank holds 1,514 dtons of Lhyd. That's a rough fill rate of 500dtons/hr.

Does someone have the UNREP rates from the book?

 

[J. L. Brown]

Roughly speaking, the space shuttle main tank holds 1,514 dtons of Lhyd. That's a rough fill rate of 500dtons/hr.

Does someone have the UNREP rates from the book?

Yeah -- an UNREP system moves 20 dTons of fuel per hour, so the equivalent to the NASA rate would be 25 dTons of UNREP equipment. Honestly, I think all the cargo & fuel handling stuff could use a re-work -- UNREP seems far too fast, and cargo loading / unloading seems too slow.

These should also probably get better with technology level.

 

[Terry Mixon]

Yeah -- an UNREP system moves 20 dTons of fuel per hour, so the equivalent to the NASA rate would be 25 dTons of UNREP equipment. Honestly, I think all the cargo & fuel handling stuff could use a re-work -- UNREP seems far too fast, and cargo loading / unloading seems too slow.

These should also probably get better with technology level.

Remember that it is 20 tons of UNREP per ton of the system you buy. You can buy ten tons of UNREP and get 200 tons of fuel an hour. 100 tons of UNREP and get 2,000 tons moved an hour. It is scalable, not static.

 

[Geir]

Yeah -- an UNREP system moves 20 dTons of fuel per hour, so the equivalent to the NASA rate would be 25 dTons of UNREP equipment. Honestly, I think all the cargo & fuel handling stuff could use a re-work -- UNREP seems far too fast, and cargo loading / unloading seems too slow.

These should also probably get better with technology level.

Cargo handling is left notoriously undefined: loading belt vs. cargo crane - random and incompatible specifics (tons versus people equivalent, very expensive versus very cheap). As for UNREP: SpaceX is doing more than 4000 tons of prop in 40ish minutes these days, so hard to say. Plus, there's a big difference between transferring liquids and moving cargo containers that's left vague.

What I'd like to see - and I'm sort of pushing this with comfort levels in vehicles, is that every choice you make on what to add or subtract should have some sort of game effect, even if peripheral: like making things fancier to match the SOC you're trying to project, or to make the ride better for long durations, or... something, doesn't have to directly be a DM to a task, but a decision to make an available ton into cargo space (free and possibly income generating) or into common space (MCr0.1 per dton and... um... er... ) should do something.

 

[Arkathan]

OK, here's my math if you want to check it:

 

[J. L. Brown]

Remember that it is 20 tons of UNREP per ton of the system you buy. You can buy ten tons of UNREP and get 200 tons of fuel an hour. 100 tons of UNREP and get 2,000 tons moved an hour. It is scalable, not static.

That is something else that I am not a fan of -- absolutely linear one-system-to-one-performance stuff. I much prefer the GURPS Traveller approach with 'cores' and 'slices' -- where a system 'core' does not necessarily have any value, but it represents the essential workings for a system. Each 'slice' you purchase increases the performance of the system, but also requires a 'Core' to be present.

Jump drives already work sort of like this -- there is a five dTon 'core' in addition to the percentage for the performance of the drive.

Ideally, each slice would produce a certain amount of capacity -- but as the amount of capacity per core grows there is diminishing returns of performance. And all of this increases / scales by TL. This makes having a multiple systems the simple matter of buying multiple 'cores'; and it might pay to have two or three (or more) systems working together rather than one big system that does it all.

 

[phavoc]

OK, here's my math if you want to check it:

View attachment 3023

Per the dimensions the SS main tank dtons displacement is stated at approx 1,500 dtons.

Of the many things we don't have is the Machinery used to pump the fuel. But we already know that ships at sea can transfer different amounts of fuel, some of which uses different sizes hoses but essentially the same equipment.

Perhaps guidelines foe sizes/classes of ships for how much 'stamdard' sized equipment is recommended for a ship to achieve reasonable times to refuel.

Moving supplies would work best by pallets or even small 2-3dton containers.that wat it's transferred quickly and the receiving ship can muster its crew to manually stow it as they move to their next assignment or duty station.

Ammunition would be the exception. Thing that can go blooey will be done safely first and quickly second.

This discussion naturally dovetail into the fuel scoop refueling process. One would expect their to be some linkage betwixt the two since plumbing would be reused as much as possible due to space constraints.

 

[Arkathan]

We know the volume of fuel that the tanks held. Rounding: 380K-390K gallons for LHyd and 145K for LOx.
A separate unrep is used for the Lox. That system can be smaller by more than half in Traveller HG22 terms.
There is no point in using the external tank dimensions, when we know the tank capacities, the volume of a gallon and the number of cubic feet in a Dton.
Going another way, 1000 kg of LHyd is a Dton. The LHyd tank held 104,000 kg of LHyd. 104 Dtons. Divided by 3 hours is ~34 Dtons per hour.
I initially went only with the LHyd, since that is the fuel of choice in Traveller.