Type ST Transport Scout: 199Td, J4/2G (LBB2 2nd Ed.)

[Grav_Moped]

In the first edition, it did align (if I remember right). Every jump regardless of distance used fuel based on the jump drive capability, not jump distance (no jump governor), and every trip used all of the power plant fuel. The Type S couldn't do a Jump-1 outbound then another Jump-1 to return without refueling in the first place, so the exact fuel burn didn't matter. It mattered when implicit jump governors (they were explicit, separate hardware in HG '77) became standard in LBB2 2nd Ed.

Realized something: In LBB2 '77, the power plant fuel was only used for maneuver, since the jump drive did not need power plant support.

In other words, Spinward Flow's endurance calculation upthread (4 weeks plus 1 week per Jump) would have been correct for LBB2 '77.

It suggests that this was overlooked in the changes for second edition. But I suspect that few players or refs built non-starships with LBB2, or gave them much thought, so it's an understandable oversight. It'd also have meant nailing down exactly how much fuel a power plant uses during Jump and for maneuver (even if merely to gloss over the matter again for the sake of simplicity).

 

[Grav_Moped]

That is a distinction without a difference since all drives, hence all ships, need a power plant.

~Shrugs in [Annic Nova language]~

 

[AnotherDilbert]

~Shrugs in [Annic Nova language]~

Even MWM can make house rules...

It's certainly not built according to LBB2'81.

 

[AnotherDilbert]

In other words, Spinward Flow's endurance calculation upthread (4 weeks plus 1 week per Jump) would have been correct for LBB2 '77.

No. In LBB2'77 there is no time given for PP fuel, just that it is always fully consumed, regardless of the length of the trip.

 

[whartung]

If we import something vaguely like a Free Trader but it has J-3 and 150 Dt cargo space, it would be much more efficient than a Free Trader at being a Free Trader.

Having 150 Dt cargo instead of the default ~80 Dt it would be much more profitable, so not forcing the characters to take side missions to make ends meet, i.e affecting game play.

Given the opportunity to upgrade their "Free Trader" to a Subbie, they would scoff at it and ask why they would want such a bad ship, barely any more cargo and only J-1?

Yes, it is an extreme example, but it hopefully illustrates what I mean.

Sure, but since I assume that the players aren't just heads down with their noses buried in the Trade rules grinding away and playing "Far Trader -- the board game", any extra "efficiencies" can be countered by a bad head gasket or a unsavory broker at the whim of the referee.

 

[Grav_Moped]

Even MWM can make house rules...

It's certainly not built according to LBB2'81.

True, but the whole game is his house.

 

[Grav_Moped]

... and more to the point, one could view T5 as the definitive house rules for LBB1-3.

That aside, I'm hitting the "agree to disagree" button on the whole thing.

If this needs to continue, I'll post a duplicate of my "favorite house rules" post about LBB2 '81 fuel use to shift the discussion out of the ship thread.

I'll probably do it anyhow.

 

[Grav_Moped]

No. In LBB2'77 there is no time given for PP fuel, just that it is always fully consumed, regardless of the length of the trip.

Thanks -- what I know of '77 is either secondhand or memory from 4 decades ago, so there are gaps.

 

[AnotherDilbert]

True, but the whole game is his house.

Annic Nova was published in JTAS#1. It gives an indication of how seriously MWM took the rules, i.e. not very.

But he never said it was a LBB2 ship. He just said here is a mysterious alien artifact, go explore...

 

[Grav_Moped]

Annic Nova was published in JTAS#1. It gives an indication of how seriously MWM took the rules, i.e. not very.

But he never said it was a LBB2 ship. He just said here is a mysterious alien artifact, go explore...

Based on the date of initial publication (JTAS #1), it was almost certainly designed in the context of the '77 rules. The DA1 version conceivably could have been informed by the 1980 High Guard rules, but since the jump drives are described as LBB2 components this is unlikely.

The subsequent interpretations of Collector-powered Jump Drives (MgT and T5) require a power source in addition to the Collector for loads other than the Jump Drive, but only one sufficient for those loads. In those rules, only the Collector rating has to equal the Jump Drive rating -- the power plant rating does not.


In fairness, jump drives and power plants are more space-efficient in larger hulls -- their volume with respect to effect (Jn*Td or Pn*Td) decreases because the drive volume formulae are both in the form "(tons*hull size*rating) plus a constant", and the constant becomes a decreasing fraction of hull tonnage as the latter increases. Maneuver drives, on the other hand, become less space-efficient with increasing hull size since their constant is a negative value (which is why the formula breaks down for maneuver drives smaller than Size A).

Where M is hull tonnage (at the tonnage values listed on the Drive Potential Table, these resolve to the "letter drive sizes"):

Jump Drive (tons) = (0.025*M*Jn)+5
Jump Drive (percent of M) = ( (0.025*M*Jn+5)/M ) *100

Power Plant (tons) = (0.015*M*Pn)+1
Power Plant (percent of M) = ( (0.015*M*Pn+1)/M )*100

Maneuver Drive (tons) = (0.01*M*G)-1 or
Maneuver Drive (percent of M) = ((0.01*M*G)-1/M)*100

... with exceptions at J1/1G/Pn-1 in 1000Td, and numerous exceptions where "M x effect" is over 4000 (that is, drive sizes W-Z -- the TL 15 drives).
The maneuver drive formula produces unlikely results for M*G<200, and impossible results for M*G<100 (maneuver drive smaller than Size A).

 

[AnotherDilbert]

The subsequent interpretations of Collector-powered Jump Drives (MgT and T5) require a power source in addition to the Collector for loads other than the Jump Drive, but only one sufficient for those loads. In those rules, only the Collector rating has to equal the Jump Drive rating -- the power plant rating does not.

T5, yes, but not MgT2.

In MgT2 the Jump drive still needs power from the power plant, the Collector only replaces the jump fuel.

 

[Grav_Moped]

T5, yes, but not MgT2.

In MgT2 the Jump drive still needs power from the power plant, the Collector only replaces the jump fuel.

MgT2, High Guard, p. 70: "This charge is released in a single spike to power a jump drive; collectors cannot be used for normal ship operations."

In MgT2, jump drives cannot require additional power after Jump initiation, or the XBoat wouldn't have enough battery capacity to carry it through a week of Jump. Its power plant supports the 20-power-point basic ship's systems requirement only. It could theoretically charge its own batteries in 4 turns if it had one more ton of power plant (3 tons @ TL8: 30 power points, instead of 2 tons and 20 power points) and half a ton more fuel. (This is assuming drives only occur in integer tonnages; if fractional tons are allowed then even less extra power plant and fuel -- but more time -- are needed to pull this off...)

And there's plenty of room (cargo) to simply double the size of the power plant and its fuel allocation, and just ditch the batteries altogether (adds MCr 1.9 to the cost, before applying quantity discounts).

Honestly, I think they were just trying too hard here.

So, in MgT they do need additional power. However, it doesn't have to come from a power plant that's the MgT analog of Pn=Jn, and it's only needed at jump initiation. This does show that jump drive efficiency isn't directly linked to power plant efficiency.

 

[AnotherDilbert]

In MgT2, jump drives cannot require additional power after Jump initiation, or the XBoat wouldn't have enough battery capacity to carry it through a week of Jump.

Like in HG'80, a jump drive requires lots of fuel plus power for a single turn.

A Collector replaces the fuel, but not the power requirement.

A battery can supply the power.

 

[Condottiere]

That would be because power usage would be acute, rather than chronic, for jump operations.

 

[Spinward Flow]

That would be because power usage would be acute, rather than chronic, for jump operations.

Exactly.
Entering jump space requires a sudden massive "spike" in power demand, while normal space operations (interplanetary travel, etc.) requires a steady "baseline" power demand over a sustained duration.

It's kind of like the difference between needing a 50 kWhour battery for a Tesla and needing 1.21 GW at 88 mph in order to time travel ...

OUTATIME image link

 

[Grav_Moped]

Like in HG'80, a jump drive requires lots of fuel plus power for a single turn.

A Collector replaces the fuel, but not the power requirement.

A battery can supply the power.

In HG (both CT editions) it requires that power output for two turns (or twice that in one turn) then that same power level for the entire 168 (+/-10%) hours of Jump. This is dictated by Pn=Jn and fuel use rates.

I just realized MgT doesn't require 2x"Pn" power points over 1 or 2 turns to initiate Jump, just "Pn"=Jn (quotes because MgT doesn't do Plant Number ratings in so many words).

 

[Condottiere]

Originally, starship fusion reactors were considered inefficient in comparison to dirtside ones, as they were designed to handle sudden spikes, when they needed to be overclocked to provide the energy for the power spike.

At least, that's the excuse for not permitting batteries, fission reactors or diesels to be used for that purpose.

 

[Spinward Flow]

In HG (both CT editions) it requires that power output for two turns (or twice that in one turn)

There is one and only one condition under which that is explicitly true ... specifically an in-combat context ... where the object is to break off from combat during the Pursuit step by jumping. If you have enough "spare" power plant energy point generation then you can break off from combat by jumping at the end of turn 1 or turn 2 of combat. If you don't have enough "spare" power plant energy to reach the threshold minimum energy points required after 2 turns of combat, you cannot jump to break off from combat.

However ... if you're NOT in combat, this threshold limitation is not a problem and you can still jump, so long as your power plant number equals or exceeds the jump number, even if the ship has its entire power budget consumed by computer demands. How long that might take to jump out of combat is never specified, just like how the energy points stored in jump capacitors is never given an expiration or "decay" time curve.

 

[Grav_Moped]

There is one and only one condition under which that is explicitly true ... specifically an in-combat context ... where the object is to break off from combat during the Pursuit step by jumping. If you have enough "spare" power plant energy point generation then you can break off from combat by jumping at the end of turn 1 or turn 2 of combat. If you don't have enough "spare" power plant energy to reach the threshold minimum energy points required after 2 turns of combat, you cannot jump to break off from combat.

However ... if you're NOT in combat, this threshold limitation is not a problem and you can still jump, so long as your power plant number equals or exceeds the jump number, even if the ship has its entire power budget consumed by computer demands. How long that might take to jump out of combat is never specified, just like how the energy points stored in jump capacitors is never given an expiration or "decay" time curve.

Which is to say, Pn=Jn is required (as per the rules). Using the "emergency agility" rule lets you disregard computer power draw. If you could use a lower generation rate and store it, everyone would do that unless they were maintaining reserve capacitor capacity for a black globe (which means the default would be to jump in 1 turn, not 2).

The 4-week fuel requirement implies that the required energy is needed through the entire jump, since the 4-week required amount is the same for starships and non-starships -- you don't get credit for reduced fuel consumption during time spent in jumpspace.

 

[kilemall]

I've given a lot of thought to the CT/HG capacitor.



That thing is a really great power to ton capacity, and I have it in every EP-using weapon system (I envision a great big 1000x shot for once every 1000s rather then the continuous fire I understand most assume).

So one of the things you need to decide EP storage means is whether that is 250 MW seconds or 250 GW seconds. I assume the latter, with power plant ratings predicated on 250 MW constant per EP.

That allows for constant ground/orbital fire at the Striker ROF.


I further assume the basic tech to it is metallic hydrogen, an outgrowth of gravitics making fusion possible.

As such, the capacitor will handle what it is supposed to, take a charge then discharge it all quickly for things that require- a laser, a spinal gun, a jump drive.

But if it retains the charge, then it starts heating up and expanding the metallic hydrogen to where it destabilizes and can potentially release all that energy- explosively, just like when they overload from receiving too much power from Black Globe Generators.


So what is the criteria for retention? I'd say it's implicit in the jump process- designed to take a full charge in the jump drive to initiate the jump.

Two turns worth of jump capacitor- I'd say your time limit is there, to avoid catastrophic capacitor detonation.

The roll would be 2D, roll below the number of turns the capacitors are charged. After two turns still no chance of detonation- after three turns a roll of 2 could detonate them, four turns a roll of 2 or 3, etc.

Detonation would be a ship-ending event in most instances.