Electric jump drive.

[Spinward Flow]

LBB2'77-DA1/MgT require significantly less energy since they don't need the equivalent of Pn=Jn running during the week in Jumpspace.

Is a portion of the 10% per parsec for jump fuel requirement needed to keep the jump field sustained during the week in jump space then?
So it's more like 9% to rip the hole open and 1% to power through until breakout?
9+1=10% per parsec

 

[spank]

Talk about a hat on a hat.

So it creates a bubble of hyperspace.
And an artificial singularity.
And exotic particles.
And a parallel universe.

What a completed departure from existing OTU canon and MWM's article on jump drive and what we are told in T5.

 

[spank]

Really? Where does it say this? Can you remember the reference?

When I made the post I was referencing the starter set on page 24 of book 2, because it was handy.
I checked the Core book, and it is on page 148, it is on page 157 of the 2022 update, and page 48 of the Explorer's edition.

 

[whulorigan]

Is a portion of the 10% per parsec for jump fuel requirement needed to keep the jump field sustained during the week in jump space then?
So it's more like 9% to rip the hole open and 1% to power through until breakout?
9+1=10% per parsec

Something like that. Or the maintenance field is low enough power draw that the Power plant can handle it (but I would go with the former).

 

[Spinward Flow]

Or the maintenance field is low enough power draw that the Power plant can handle it (but I would go with the former).

Simpler (game mechanically speaking) to assume that the 10% jump fuel requirement covers both the "punch a hole" as well as "field sustain for 1 week until breakout" inclusive. However, the power plant would still need to supply "housekeeping" power to the starship for the 1 week duration while in jump ... but there is no need for maneuver, weapons or screens to be powered while in jump. However, keeping the computer supplied with EP during the week in jump will be required.

 

[Condottiere]

Currently, it doesn't matter.

Presumably, the bubble is filled, the jump drive switches off, and over the next week, the balloon deflates.

 

[mike wightman]

When I made the post I was referencing the starter set on page 24 of book 2, because it was handy.
I checked the Core book, and it is on page 148, it is on page 157 of the 2022 update, and page 48 of the Explorer's edition.

Many thanks.

 

[Grav_Moped]

Is a portion of the 10% per parsec for jump fuel requirement needed to keep the jump field sustained during the week in jump space then?
So it's more like 9% to rip the hole open and 1% to power through until breakout?
9+1=10% per parsec

The reason I called out power (and fuel) use for '79-and-up starships is that non-starships don't get "free" extra endurance for not being in Jump for half the time (2 jump per month tempo). This means that something about Jump requires Pn=Jn power input during the time in Jump -- and it's not baseline power, since that's going to be somewhere below Pn=1, not Jn except for J1, and it should be less than Pn=Jn=1 anyhow. Mongoose (and others) are more granular about this.

'77 ships power fuel allows for "one trip" including possibly multiple jumps (it's essentially maneuver fuel renamed and handwaved), and the XBoat needs no power plant fuel in that system (or even a power plant to burn it).

 

[AnotherDilbert]

The reason I called out power (and fuel) use for '79-and-up starships is that non-starships don't get "free" extra endurance for not being in Jump for half the time (2 jump per month tempo). This means that something about Jump requires Pn=Jn power input during the time in Jump -- ...

There is a canon explanation:

HG'79, pp17:
A power plant uses fuel equal to 1% of the ship's tonnage every four weeks, regardless of actual power drain; this usage is primarily to maintain the fusion bottle and other housekeeping functions. Other fuel requirements are considered inconsequential.

Fuel consumption has nothing to do with power consumption...

 

[Krikkitone]

I could also buy that the hydrogen is being used, not to make EP, but to generate exotic "jump particles". But that would seem to prelclude fusion and antimatter powered jump drives.

That’s my head cannon. With the idea that fusion of hydrogen is what produces the “jump particles,” (and a collector can collect and convert them…as well as antimatter being usable for that)

 

[Grav_Moped]

There is a canon explanation:

Fuel consumption has nothing to do with power consumption...

Again, with my "this is what made the rules make no sense, so I'll make sense of it anyhow" angle on this.

They basically, item by item, ruled out every specific power draw -- particularly maneuver -- as being related to fuel use, so they could just declare that 1%*Pn as a fiat statement to simplify High Guard.

So nothing actually uses fuel except the power plant just being a power plant. If it's on, it's on the whole month and it's drawing 1%*Pn over that month to do it.

And then you get the TCS/JTAS#14 Power Down rule, which says that a power plant doesn't need to use 1% * "rated Pn", fuel per month, but can use 1% * "Pn as used," fuel per month instead.

How exactly is that supposed to work? How can you cut fuel use by "powering down" if nothing you're doing -- or not doing -- with the power plant can change the fuel use from that 1% * Pn per month?

 

[Grav_Moped]

They basically, item by item, ruled out every specific power draw -- particularly maneuver -- as being related to fuel use, so they could just declare that 1%*Pn as a fiat statement to simplify High Guard.

I mean, the power-down rules are blatantly a game mechanic to allow a task force to hide in an enemy-occupied star system for a number of week-long turns, hoping that either the hostiles leave, or some friendlies arrive and displace the hostiles. And it puts a time limit on how long they can hold out, and makes it so that this can only work once.

But it has significant implications for the rest of how ships work in the game universe, some of which are likely unintended.

 

[Grav_Moped]

But it has significant implications for the rest of how ships work in the game universe, some of which are likely unintended.

... and which I ruthlessly exploit at almost every turn in my own house-rules, because it makes more sense that way.
(See, for example, most of my own-design ship designs: LBB2 400Td 6Boat at TL-12, 199Td J-4/2G "Oversize Type S" at TL-10, my interpretation of the XBoat for LBB2'81, and so forth...)

My Impala (the Gazelle -- but built in, and for use with, LBB2), Shugushaag (LBB2 600Td J5 Far Trader), and Long Scout (LBB5 J-5 "Oversize Type-S") designs don't do this, though. (Ok, the Impala uses it a little bit....)

 

[Condottiere]

Power plant rules are sparse, and High Guard certainly doesn't spell out options regarding energy generation for each type, except for solar panelling in the current one, and that has to do with distance and luminosity.

Logic says there should be a range to allow optimum fuel usage over power generation, as well as how long it takes to start up a fusion reactor from a shut off condition.

 

[Spinward Flow]

They basically, item by item, ruled out every specific power draw -- particularly maneuver -- as being related to fuel use, so they could just declare that 1%*Pn as a fiat statement to simplify High Guard.

So nothing actually uses fuel except the power plant just being a power plant. If it's on, it's on the whole month and it's drawing 1%*Pn over that month to do it.

And then you get the TCS/JTAS#14 Power Down rule, which says that a power plant doesn't need to use 1% * "rated Pn", fuel per month, but can use 1% * "Pn as used," fuel per month instead.

How exactly is that supposed to work? How can you cut fuel use by "powering down" if nothing you're doing -- or not doing -- with the power plant can change the fuel use from that 1% * Pn per month?

Think of it like this.

There are 2 basic levels of EP demand (technically 3, but since the 3rd is a subset of the previous 2, it's more like 2.2).

1. Non-combat
2. Combat
   • Emergency Agility

Those are your output levels needed from the power plant.
Obviously the EP demands during combat are going to be higher (and possibly "over the maximum limit" by a little bit under Emergency Agility) than they will be when Not In Combat (which will easily be 99%+ of a starship hull's usable lifetime).

In other words, you don't need the power plant to be running "full blast, full time" ALL the time, regardless of context or circumstances.

I mean ... how many meson guns and nuclear missiles are you going to have trying to hit you during a week in jump space?
My answer ... not many ... ... so those screens can be powered down while in jump (for example).

Weapons, screens and maneuver agility are "irrelevant" in a lot of non-combat circumstances (such as jump, docking maneuvers at a friendly highport, in a hangar berth, etc.) so you don't need the power plant "running full blast" at combat power the entire time, consuming fuel to produce power you aren't going to be using.

However, at the Naval Architect Design step, for reasons of safety margins, you MUST assume that a power plant will be "running full blast" on combat power for a minimum of 28 days (hence the fuel requirement of 1%MPn in LBB5.80 and onwards). Since the starship construction rules operate on a "combat ready" basis, those are the numbers we are given and required to deal with.

How exactly is that supposed to work?

Simple.
If you aren't running your power plant at 100% full time, your mission endurance extends beyond the minimum of 28 days.
Consume less fuel, extend the duration until you must refuel.

The error of assumption is in thinking that the 28 days of power plant fuel endurance is a "hard" limit, regardless of context ... rather than being a "at maximum power output you have 28 days of fuel endurance" more nuanced interpretation.

A lot of these questions get MUCH easier to answer with the (normal space extended duration operations) rules found in CT Beltstrike, because they solve a LOT of these questions.

Furthermore, the "compute consumption" rules of CT Beltstrike do not invalidate the fuel allocation rules of LBB2.81 or LBB5.80 used for starship CONSTRUCTION at all. Instead, the CT Beltstrike rules of fuel consumption provide the necessary context and understanding to calculate endurance when NOT continuously in combat (which for most commercial operators is going to be the vast supermajority of the time).

Extremely simplified, the CT Beltstrike fuel consumption rates amount to:

• 1 EP = 0.35 tons of fuel consumed per 7 days
• 700 tons of hull = 0.35 tons of fuel consumed per 7 days for "basic power"

LBB2.81 standard drive "excessive fuel" allocation requirements at the design and construction stages simply means that craft designed with those drives (if under 1000 tons) are required to have "extra safety margins" built into the fuel allocation, which ultimately means that their power plant endurance run times will EASILY exceed the 28 day minimum design margin requirement.

LBB5.80 custom drive "more economical" allocation requirements at the design and construction stages simply means that craft design with those drives "have tighter safety margins" built into the fuel allocation, which ultimately means that their power plant endurance run times will more commonly come closer to the 28 day minimum design margin requirement.

When taking into account that LBB2.81 drives are going to be more commonly used for civilian purposes (nothing "secret" about the details or engineering involved), while the LBB5.80 drives are going to more "uniquely suited" to the class that they are installed into (so potentially military secrets can be involved), it starts making a bit more sense.



As soon as you let go of the notion that the ENTIRE fuel allocation MUST be consumed/burned/destroyed/lost every 28 days, regardless of demand in ship performance ... and instead switch over to measuring how much fuel IS CONSUMED per day in various contexts, these kinds of questions about endurance tend to resolve themselves somewhat neatly and the 28 day limit goes from being a maximum limit to a minimum limit.

 

[kilemall]

Think of it like this.

There are 2 basic levels of EP demand (technically 3, but since the 3rd is a subset of the previous 2, it's more like 2.2).

1. Non-combat
2. Combat
   • Emergency Agility

Those are your output levels needed from the power plant.
Obviously the EP demands during combat are going to be higher (and possibly "over the maximum limit" by a little bit under Emergency Agility) than they will be when Not In Combat (which will easily be 99%+ of a starship hull's usable lifetime).

In other words, you don't need the power plant to be running "full blast, full time" ALL the time, regardless of context or circumstances.

I mean ... how many meson guns and nuclear missiles are you going to have trying to hit you during a week in jump space?
My answer ... not many ... ... so those screens can be powered down while in jump (for example).

Weapons, screens and maneuver agility are "irrelevant" in a lot of non-combat circumstances (such as jump, docking maneuvers at a friendly highport, in a hangar berth, etc.) so you don't need the power plant "running full blast" at combat power the entire time, consuming fuel to produce power you aren't going to be using.

However, at the Naval Architect Design step, for reasons of safety margins, you MUST assume that a power plant will be "running full blast" on combat power for a minimum of 28 days (hence the fuel requirement of 1%MPn in LBB5.80 and onwards). Since the starship construction rules operate on a "combat ready" basis, those are the numbers we are given and required to deal with.

Simple.
If you aren't running your power plant at 100% full time, your mission endurance extends beyond the minimum of 28 days.
Consume less fuel, extend the duration until you must refuel.

The error of assumption is in thinking that the 28 days of power plant fuel endurance is a "hard" limit, regardless of context ... rather than being a "at maximum power output you have 28 days of fuel endurance" more nuanced interpretation.

A lot of these questions get MUCH easier to answer with the (normal space extended duration operations) rules found in CT Beltstrike, because they solve a LOT of these questions.

Furthermore, the "compute consumption" rules of CT Beltstrike do not invalidate the fuel allocation rules of LBB2.81 or LBB5.80 used for starship CONSTRUCTION at all. Instead, the CT Beltstrike rules of fuel consumption provide the necessary context and understanding to calculate endurance when NOT continuously in combat (which for most commercial operators is going to be the vast supermajority of the time).

Extremely simplified, the CT Beltstrike fuel consumption rates amount to:

• 1 EP = 0.35 tons of fuel consumed per 7 days
• 700 tons of hull = 0.35 tons of fuel consumed per 7 days for "basic power"

LBB2.81 standard drive "excessive fuel" allocation requirements at the design and construction stages simply means that craft designed with those drives (if under 1000 tons) are required to have "extra safety margins" built into the fuel allocation, which ultimately means that their power plant endurance run times will EASILY exceed the 28 day minimum design margin requirement.

LBB5.80 custom drive "more economical" allocation requirements at the design and construction stages simply means that craft design with those drives "have tighter safety margins" built into the fuel allocation, which ultimately means that their power plant endurance run times will more commonly come closer to the 28 day minimum design margin requirement.

When taking into account that LBB2.81 drives are going to be more commonly used for civilian purposes (nothing "secret" about the details or engineering involved), while the LBB5.80 drives are going to more "uniquely suited" to the class that they are installed into (so potentially military secrets can be involved), it starts making a bit more sense.



As soon as you let go of the notion that the ENTIRE fuel allocation MUST be consumed/burned/destroyed/lost every 28 days, regardless of demand in ship performance ... and instead switch over to measuring how much fuel IS CONSUMED per day in various contexts, these kinds of questions about endurance tend to resolve themselves somewhat neatly and the 28 day limit goes from being a maximum limit to a minimum limit.

This is the way I have thought about it for most of the Traveller run. Nowadays I am a little more nuanced as I am hand waving heat exhaust as the main reason for fuel consumption- run up the power use even without m drive and that heat still has gotta go.