Pondering starship evolution

[Grav_Moped]

Which is why I would argue that during jump, the power plant doesn't need to be "running at full blast" the entire way. Basic Power (housekeeping) and sufficient EPs to keep the main computer running is "enough load" for the power plant during jump and anything additional would be superfluous (in terms of EP generation). Starships are basically "inertial coasting" through jump ... the same way that a non-starship can "inertial coast" without acceleration on a trajectory after an initial maneuver burn, in order to save on fuel consumption.

All of the fuel "needed" during the jump (initiate, coast, breakout) MUST be available to the jump drive at the START of a jump, so as to ensure an uninterruptible supply of fuel to the jump drive during the entire jump (start to breakout) ... and THAT value is the one we (as gamers) know from the rules and game mechanics.

The power plant number needs to be equal to or higher than the jump drive number so as to make sure that the power plant can "do its part" of handling the power load at the start of a jump (you must be THIS HIGH to jump this far!), but that's a "peak load" requirement rather than a "steady state for the entire week during jump" requirement.

It does (based on fuel consumption) need to be running at Pn=Jn during the time in Jump (2nd Ed). It needs to be either Pn=2Jn for a prompt Jump, or Pn=Jn for a normal Jump (but with a delay to get the capacitors charged -- there's math I'm choosing not to do right now that would express this in terms of Energy Points). (This is also WRT 2nd Ed, not 1st or any version of Mongoose rules.)

Now, one thing that bothers me about those PP fuel burn rates is that in normal operation (that is, RAW), PP fuel burn is at nameplate Pn rather than Pn-as-used (2nd Ed). It's like they have Jump Governors but not Power Plant Governors... a Type T Patrol Cruiser (LBB2 J3/4G/Pn-4) doing J-3 still uses 10Td fuel in Jump (1/4 of 40Td, not of 30Td for Pn-3) for just the power plant (and of course, the normal 120Td fuel for the Jump Drive for that J-3).

It also uses that 10Td (not 2.5Td) for a mere J-1...

ETA: the same scaling effect applies to LBB5 ships, but it's not obvious until you're dealing with ships having Pn ratings well above 6 because the LBB5 power plant fuel requirements are so much lower in ACS-sized ships.

 

[Spinward Flow]

Now, one thing that bothers me about those PP fuel burn rates is that in normal operation (that is, RAW), PP fuel burn is at nameplate Pn rather than Pn-as-used (2nd Ed).

Obviously a simplification to avoid excess word count (to keep the page count within acceptable limits) as an editorial decision. If all you're using Traveller for is "tabletop wargame" then such details fall below the granularity of what a Referee (or Players, for that matter) Need To Know™. However, that bit of premature optimization discounted the need for "extended endurance on station" without refueling, which gets away from the "tabletop wargame" (combat) side of things that most murder hobos Players care about and starts drifting into the verboten realm of Space Life Simulator that Traveller wasn't aiming to be about.

It does (based on fuel consumption) need to be running at Pn=Jn during the time in Jump (2nd Ed).

Citation REQUIRED.
Prove your assertion that power plants need to be running "full blast" during the entire duration of jumps, "destroying" precious fuel for an entire week to generate EPs that (probably) aren't needed by any onboard systems.

Assertions are one thing.
Proofs are another (more important) thing.

It needs to be either Pn=2Jn for a prompt Jump, or Pn=Jn for a normal Jump (but with a delay to get the capacitors charged -- there's math I'm choosing not to do right now that would express this in terms of Energy Points).

LBB5.80, p39 ... Breaking Off by Jumping.

A starship needs a power plant capable of generating sufficient EPs in order to deliver 2x0.01MJn to the jump drive in 2 combat turns or less in order to jump. If a power plant cannot deliver the required amount of EPs within 2 combat turns, that jump (number) may not be attempted.

So to use a Type-S Scout/Courier as a highly simplified example ... the A/A/A drives installed yield codes: 2/2/2 in a 100 ton hull.

• A J2 in a 100 ton hull requires 2*0.01*100*2=4 EP delivered to the jump drive within 2 combat turns in order to J2.
• A J1 in a 100 ton hull requires 2*0.01*100*1=2 EP delivered to the jump drive within 2 combat turns in order to J2.

The installed power plant has a generating capacity of EP=2 ... and a stock (unmodified) Type-S Scout/Courier has no EP consuming systems other than the maneuver drive. Therefore ...

• A Type-S Scout/Courier requires 2 combat rounds of EP=2 generation dedicated to the jump drive in order to J2.
• A Type-S Scout/Courier requires 1 combat round of EP=2 generation dedicated to the jump drive in order to J1.

Note that any EP consuming maneuver agility, weapons, screens or computers cannot be "demanding" EP during the preparation to jump, because there's no EP generation reserve capacity to do more than prepare for jump during those 1-2 combat turns. If nothing is shooting at you that's not a problem ... but if you ARE being shot at ... dropping your maneuver agility to 0 in order to jump away might not be the best option under the circumstances.

All of the above outlines the "peak load" demand from the power plant in order to be able to jump (at all).
There is absolutely nothing in the above cited section stating that the power plant EP demand for the jump drive is CONTINUOUS throughout the entire jump until breakout.
If you want to prove me wrong (convincingly) on that point, CITATION REQUIRED.



Again, I fall back to the analogy of "limited delta-v maneuvering" (common in the chemical rocketry era) in normal space.

While a craft is "coasting" on momentum only, with no acceleration at all in normal space, the power plant does not need to be working "at full blast" the entire time. When power demand during an inertial cruise phase drops to "near zero" for Basic Power only with the maneuver drive "shut down" and no weapons or screens powered up (in normal space) because there is no maneuver acceleration happening (and no combat happening), the fuel demand of a power plant drops down to the Basic Power only level. The only onboard system that ought to be be consuming EP=1+ during such an inertial cruise phase would be the computer (assuming model/3+).

The SAME conditions apply to a starship during jumps, where a starship is "inertial coasting" the whole way to the destination breakout point.

• While a starship is in jump, there is no need for maneuver ... so shut down the maneuver drive (Agility=0 means EP=0).
• While a starship is in jump, there is no need for weapons ... so shut down the weapon systems (EP=0).
• While a starship is in jump, there is no need for screens ... so shut down the screens (EP=0).
• While a starship is in jump, there IS a need to keep the main computer powered ... so keep generating EPs for the computer to stay online (model/1-2 computers consume EP=0).

Travellerwiki article: Jump Drive

During the week in jump the responsibilities of the crew are directed toward maintaining life support within the ship, repair and maintenance of some ship systems, and care of the passengers.

To me, that sounds like Basic Power fuel consumption demand persists during jump (obviously), but other types of EP demand (aside from keeping the computer operational) cease to be a factor.

ETA: the same scaling effect applies to LBB5 ships, but it's not obvious until you're dealing with ships having Pn ratings well above 6 because the LBB5 power plant fuel requirements are so much lower in ACS-sized ships.

Hence why I prefer the interpretation that the fuel tonnages "required" by LBB2 and LBB5 represent construction REGULATIONS for minimums, rather than any kind of direct reference/calculation to fuel consumption rates. The regulations stipulate a quantity that ought to be sufficient margin for (relatively) safe operation on the regular ... and nothing more. The "required tonnage" is specified as the minimums required to achieve reasonable safety margins.

How the fuel gets "used" during craft operations can vary WIDELY ... up to and including Type-S Scout/Couriers, with their 40 ton fuel tanks, being capable of J2+1 without refueling, even though the construction regulations stipulate mandatory minimums for J2 only ... because Fuel Is Fungible between jump range and normal space operational endurance.

 

[Rupert]

So to use a Type-S Scout/Courier as a highly simplified example ... the A/A/A drives installed yield codes: 2/2/2 in a 100 ton hull.

• A J2 in a 100 ton hull requires 2*0.01*100*2=4 EP delivered to the jump drive within 2 combat turns in order to J2.
• A J1 in a 100 ton hull requires 2*0.01*100*1=2 EP delivered to the jump drive within 2 combat turns in order to J2.

The installed power plant has a generating capacity of EP=2 ... and a stock (unmodified) Type-S Scout/Courier has no EP consuming systems other than the maneuver drive. Therefore ...

• A Type-S Scout/Courier requires 2 combat rounds of EP=2 generation dedicated to the jump drive in order to J2.
• A Type-S Scout/Courier requires 1 combat round of EP=2 generation dedicated to the jump drive in order to J1.

Note that any EP consuming maneuver agility, weapons, screens or computers cannot be "demanding" EP during the preparation to jump, because there's no EP generation reserve capacity to do more than prepare for jump during those 1-2 combat turns. If nothing is shooting at you that's not a problem ... but if you ARE being shot at ... dropping your maneuver agility to 0 in order to jump away might not be the best option under the circumstances.

Note that you could charge up for a J-1 over the course of two turns, freeing up 1 EP for your manoeuvre drive or for a laser. It won't make a difference is a real warship is shooting at you, but then there's not a lot a Type-S can do if it finds itself in that situation. Surrender and hope the attacker is in a good mood is probably the best course of action.

 

[Spinward Flow]

The other stipulation that I make is that during jump, a starship's power plant only needs to generate sufficient EPs to power the starship's computer and provide Basic Power (life support, housekeeping, etc.).

• There's no "maneuvering" during jump, so no need to generate EPs for agility/maneuvering
• There's nothing to "shoot at" during jump, so all weapons can be powered down and taken offline until breakout from jump
• There's nothing "shooting you" during jump, so all defensive screens can be powered down and taken offline until breakout from jump

Computers, though, will require their full budget of EPs to continue operating while in jump.

So, basically, during the "week in jump" ... the power plant fuel consumption rate is going to be Basic Power (Tonnage/2000) plus however many EPs are needed by the starship's computer (EP*0.35).

Disagree, based on LBB2 & 5 (2nd Ed. for each). Starships and non-starships have identical power plant fuel requirements, despite non-starships not spending two of every four weeks (canon jump cadence) in Jump. If no power for the jump drive (and thus no fuel) were needed during Jump, non-starships would use half as much power plant fuel as starships.

It does (based on fuel consumption) need to be running at Pn=Jn during the time in Jump (2nd Ed).

Citation REQUIRED.
Prove your assertion that power plants need to be running "full blast" during the entire duration of jumps, "destroying" precious fuel for an entire week to generate EPs that (probably) aren't needed by any onboard systems.

Assertions are one thing.
Proofs are another (more important) thing.

Again, I fall back to the analogy of "limited delta-v maneuvering" (common in the chemical rocketry era) in normal space.

While a craft is "coasting" on momentum only, with no acceleration at all in normal space, the power plant does not need to be working "at full blast" the entire time. When power demand during an inertial cruise phase drops to "near zero" for Basic Power only with the maneuver drive "shut down" and no weapons or screens powered up (in normal space) because there is no maneuver acceleration happening (and no combat happening), the fuel demand of a power plant drops down to the Basic Power only level. The only onboard system that ought to be be consuming EP=1+ during such an inertial cruise phase would be the computer (assuming model/3+).

The SAME conditions apply to a starship during jumps, where a starship is "inertial coasting" the whole way to the destination breakout point.

• While a starship is in jump, there is no need for maneuver ... so shut down the maneuver drive (Agility=0 means EP=0).
• While a starship is in jump, there is no need for weapons ... so shut down the weapon systems (EP=0).
• While a starship is in jump, there is no need for screens ... so shut down the screens (EP=0).
• While a starship is in jump, there IS a need to keep the main computer powered ... so keep generating EPs for the computer to stay online (model/1-2 computers consume EP=0).

Travellerwiki article: Jump Drive

During the week in jump the responsibilities of the crew are directed toward maintaining life support within the ship, repair and maintenance of some ship systems, and care of the passengers.

To me, that sounds like Basic Power fuel consumption demand persists during jump (obviously), but other types of EP demand (aside from keeping the computer operational) cease to be a factor.

9+ days of opportunity for proof(s) of assertion that power plants need to be generating 0.01MJn EPs continuously during jump to support the jump drive ... have not been produced, referenced or even hinted at.

Absence of Evidence is not ipso facto evidence of absence ... but a strongly negative inference can be drawn from the fact that no evidence to support @Grav_Moped's assertion(s) have been produced (thus far, as of this reply post, by anyone).



The high cost in fuel in order to jump "pays for" the operation of the jump drive during the entire duration of the jump. The "power demand curve" chart for a jump is a mighty SPIKE of demand at the beginning (to enter jump), which then sets the Peak Demand Threshold for how many EPs the power plant must produce within a limited span of time (2 combat turns ≈ 40 minutes) in order to enter jump @ that Jn ... hence why Pn must be equal to or higher than Jn when designing starships. The requirement is to be able to meet that peak demand load.

But then once a starship is in jump, there's "nothing to do" for all EP consuming systems (except the computer!) until breakout at the end of jump ... so the starship is "inertial coasting" the whole way through jump until breakout (a "week" later).

This EP demand profile during a jump, when put into chart form, looks EXACTLY THE SAME as that of an analogous non-starship (or small craft) "inertial cruising" at zero acceleration (and no combat threats) through normal space with no weapons or screens powered up (only the computer, again).



Fuel consumption rates can vary WIDELY depending on how a craft is actually used (see: Belters doing prospecting work in normal space).

But at the Naval Architect's Office when craft are being designed for construction, there are Rules & Regulations concerning fuel tankage minimums required to provide "adequate minimum endurance" expectations for safety in fuel margins regardless of how a craft is used in actual operations. Those minimum requirements are the Fuel Tankage Formulas that we know and love (to hate on) as Referees and Players.

You can always have more fuel tankage than the mandatory minimums demanded for construction ... but you're "not allowed" to build a craft with LESS than the mandatory minimums laid out in the construction system.

How you USE the fuel allotment built into your craft (and thus, the fuel consumption RATE) will vary WIDELY depending on context, circumstances, uses and corner cases ... with "battle damage" and misjumps(!) being two of the potential corner cases.

Your mileage may vary (A LOT!), of course.

 

[kilemall]

9+ days of opportunity for proof(s) of assertion that power plants need to be generating 0.01MJn EPs continuously during jump to support the jump drive ... have not been produced, referenced or even hinted at.

Absence of Evidence is not ipso facto evidence of absence ... but a strongly negative inference can be drawn from the fact that no evidence to support @Grav_Moped's assertion(s) have been produced (thus far, as of this reply post, by anyone).



The high cost in fuel in order to jump "pays for" the operation of the jump drive during the entire duration of the jump. The "power demand curve" chart for a jump is a mighty SPIKE of demand at the beginning (to enter jump), which then sets the Peak Demand Threshold for how many EPs the power plant must produce within a limited span of time (2 combat turns ≈ 40 minutes) in order to enter jump @ that Jn ... hence why Pn must be equal to or higher than Jn when designing starships. The requirement is to be able to meet that peak demand load.

But then once a starship is in jump, there's "nothing to do" for all EP consuming systems (except the computer!) until breakout at the end of jump ... so the starship is "inertial coasting" the whole way through jump until breakout (a "week" later).

This EP demand profile during a jump, when put into chart form, looks EXACTLY THE SAME as that of an analogous non-starship (or small craft) "inertial cruising" at zero acceleration (and no combat threats) through normal space with no weapons or screens powered up (only the computer, again).



Fuel consumption rates can vary WIDELY depending on how a craft is actually used (see: Belters doing prospecting work in normal space).

But at the Naval Architect's Office when craft are being designed for construction, there are Rules & Regulations concerning fuel tankage minimums required to provide "adequate minimum endurance" expectations for safety in fuel margins regardless of how a craft is used in actual operations. Those minimum requirements are the Fuel Tankage Formulas that we know and love (to hate on) as Referees and Players.

You can always have more fuel tankage than the mandatory minimums demanded for construction ... but you're "not allowed" to build a craft with LESS than the mandatory minimums laid out in the construction system.

How you USE the fuel allotment built into your craft (and thus, the fuel consumption RATE) will vary WIDELY depending on context, circumstances, uses and corner cases ... with "battle damage" and misjumps(!) being two of the potential corner cases.

Your mileage may vary (A LOT!), of course.

Generally speaking it’s not worth the effort to refute these assertions.

You're going to interpret according to your aesthetics, AD will do as he wills, we all do some messing about, and the RAW is fabulously inconsistent meaning there is likely justification for any position if one squints selectively.

The only real value IMO is exploring play consequences of whichever way one goes so refs can make informed decisions about what sort of universe they are running.

 

[Grav_Moped]

9+ days of opportunity for proof(s) of assertion that power plants need to be generating 0.01MJn EPs continuously during jump to support the jump drive ... have not been produced, referenced or even hinted at.

Absence of Evidence is not ipso facto evidence of absence ... but a strongly negative inference can be drawn from the fact that no evidence to support @Grav_Moped's assertion(s) have been produced (thus far, as of this reply post, by anyone).



The high cost in fuel in order to jump "pays for" the operation of the jump drive during the entire duration of the jump. The "power demand curve" chart for a jump is a mighty SPIKE of demand at the beginning (to enter jump), which then sets the Peak Demand Threshold for how many EPs the power plant must produce within a limited span of time (2 combat turns ≈ 40 minutes) in order to enter jump @ that Jn ... hence why Pn must be equal to or higher than Jn when designing starships. The requirement is to be able to meet that peak demand load.

But then once a starship is in jump, there's "nothing to do" for all EP consuming systems (except the computer!) until breakout at the end of jump ... so the starship is "inertial coasting" the whole way through jump until breakout (a "week" later).

This EP demand profile during a jump, when put into chart form, looks EXACTLY THE SAME as that of an analogous non-starship (or small craft) "inertial cruising" at zero acceleration (and no combat threats) through normal space with no weapons or screens powered up (only the computer, again).



Fuel consumption rates can vary WIDELY depending on how a craft is actually used (see: Belters doing prospecting work in normal space).

But at the Naval Architect's Office when craft are being designed for construction, there are Rules & Regulations concerning fuel tankage minimums required to provide "adequate minimum endurance" expectations for safety in fuel margins regardless of how a craft is used in actual operations. Those minimum requirements are the Fuel Tankage Formulas that we know and love (to hate on) as Referees and Players.

You can always have more fuel tankage than the mandatory minimums demanded for construction ... but you're "not allowed" to build a craft with LESS than the mandatory minimums laid out in the construction system.

How you USE the fuel allotment built into your craft (and thus, the fuel consumption RATE) will vary WIDELY depending on context, circumstances, uses and corner cases ... with "battle damage" and misjumps(!) being two of the potential corner cases.

Your mileage may vary (A LOT!), of course.

As @kilemall said (and I missed when first replying):
"Generally speaking it’s not worth the effort to refute these assertions."

ETA: Yep,

Not worth the effort.

If you want to call it a win, go right ahead.

[Shrug.]

 

[Grav_Moped]

The only real value IMO is exploring play consequences of whichever way one goes so refs can make informed decisions about what sort of universe they are running.

This.

 

[mike wightman]

Jump drives requiring power in jump space is rules edition specific, certainly in High Guard '80 and LBB:2 81 a power plant is required to be the same rating as the jump drive, power plant fuel is used regardless of being in jump or not so the implication is that the power plant runs at full for the whole four weeks regardless of jump space or normal space location.

LBB:2 states four weeks of operations and maneuver, so does the week in jump count as manuvering, is the power plant pushing electricity through the jump drive instead of the maneuver drive?

LBB:5 states "the power plant converts fuel to energy for computers, jump drives, maneuver drives, weapons, and screens"
this reads to me like the power plant powers the jump drive while it is in use.

Do the rules in TCS say anything about conserving fuel by powering down while in jump space? Nope, only in normal space.

There is wiggle room for house rules, but the consensus, and text in some editions, is that the jump drive is powered while you are in jump space to maintain the jump field that protects the ship from hyperspace.

 

[Spinward Flow]

Jump drives requiring power in jump space is rules edition specific, certainly in High Guard '80 and LBB:2 81 a power plant is required to be the same rating as the jump drive, power plant fuel is used regardless of being in jump or not so the implication is that the power plant runs at full for the whole four weeks regardless of jump space or normal space location.

See above: Peak vs Continuous Load argument(s).

LBB:2 states four weeks of operations and maneuver, so does the week in jump count as manuvering, is the power plant pushing electricity through the jump drive instead of the maneuver drive?

An (obvious) oversimplification of the "Pay no attention to the little man behind the curtain!" variety.
As a gameplay mechanic, it "works" to stipulate that you get 4 weeks of endurance (and no more) ... regardless of how you use your craft or what you're doing with it.

It only becomes problematic when "fuel consumption is VARIABLE depending on what you're DOING" ... rather than a constant ... in determining endurance. Under most LBB1-3 assumptions, that's never a consideration because star systems have only a single mainworld in them (and nothing else) and all Travellering worth bothering with is either interstellar (jump drives) or on planets (vehicles). Maneuver drives are almost an afterthought.

Constant fuel consumption is SIMPLE.
Variable fuel consumption is (more) COMPLEX (because it has to be).

Constant fuel consumption simplifies a LOT of extraneous questions (out of existence) when dealing with One Shot Adventures™ and tabletop wargaming.
Variable fuel consumption is necessary when dealing with Long Endurance Contexts™ (like being a Belter doing prospecting) and needing more of a Space Life Simulator type of accounting system for fuel use, depending on context.

LBB:5 states "the power plant converts fuel to energy for computers, jump drives, maneuver drives, weapons, and screens"
this reads to me like the power plant powers the jump drive while it is in use.

AGAIN ... See: Peak Load vs Continuous Load argument(s) previously made above (more than once) in this thread.

Do the rules in TCS say anything about conserving fuel by powering down while in jump space? Nope, only in normal space.

Why would TCS address this point at all?
TCS is about building fleets and "throwing them into the arena" demolition derby style, to see which designs come out on top.
TCS is not about long endurance missions ("To seek out new life, and new civilizations.") of exploration, survey or prospecting in normal space (because there's not a whole lot to be explored, surveyed or prospected in jump space).

There is wiggle room for house rules, but the consensus, and text in some editions, is that the jump drive is powered while you are in jump space to maintain the jump field that protects the ship from hyperspace.

Then explain why the jump drive needs to be powered by power plant fuel (continuous load) during jump ... AND ... explain why that fuel consumption by the power plant isn't already "bundled" in the fuel consumption rate needed to enter jump.

There is wiggle room for house rules, but the consensus, and text in some editions

So ... LBB1-3 = RAW.
LBB5.80 = RAW.
LBB A5 Trillion Credit Squadron = RAW.

CT Beltstrike = ... not RAW ...?
CT Beltstrike = House Rules ...?

Would you also say that Snapshot ... or Azhanti High Lightning ... are also "not RAW" and are House Rules too?
What about Striker?

I'm honestly curious HOW (and WHERE) you draw that particular line.



Or is it simply a matter of:

• Things I agree with = RAW
• Things I don't want to accept = Not RAW = House Rules

For example, I myself have no (great) love for later editions of Traveller post-Classic/Golden Age era ... but I would never deny them the status of being RAW for their edition(s). Doing so would be intellectually dishonest, you see.

 

[kilemall]

There is a big discrepancy between potential output going to the jump drive and the required capacitor for jump itself, indicating the jump drive converts at least some of that fuel into a power surge.

 

[Spinward Flow]

Fighter Gunned (Type-FG, TL=9)
24 ton small craft hull, configuration: 1 (MCr2.88, integral fuel scoops)
0 tons for Armor: 0 (TL=9, Composite Laminates, bulkhead thickness=18cm)
3 tons for LBB2.81 standard Maneuver-B (Agility=6 requires 1.44 EP) (MCr8)
10 tons for LBB2.81 standard Power Plant-C (EP=6) (MCr24)
0.2 tons for Jump Capacitors (7.2 EP storage) (MCr0.8)
1 ton for fuel (5d 18h 09m endurance @ 3.44 EP output+basic power continuous) (basic power only consumes 0.012 tons of fuel per 7d)
4.8 tons for bridge (2 crew acceleration couches, life support endurance: 12-24 hours) (MCr0.12)
3 tons for model/3 computer (EP: 1) (MCr18)
1 ton for triple turret: pulse laser, pulse laser, pulse laser (TL=9, batteries: 1, code: 2, EP: 3) (MCr2.6)
* External Docking: 376 tons capacity (MCr0.752)
1 ton for cargo hold

• 1 ton capacity segregated reserve internal demountable fuel tank (MCr0.001)

= 0+3+10+1.2+1+4.8+3+1+1 = 24 tons
= 2.88+0+8+24+0.8+0.12+18+2.6+0.752+0.001 = MCr57.153

• 1G, Agility=0: 400 - 24 = 376 tons external load (15x 24 ton Boxes)
• 2G, Agility=1: 200 - 24 = 176 tons external load (7x 24 ton Boxes)
• 3G, Agility=1: 133 - 24 = 109 tons external load (4x 24 ton Boxes)
• 4G, Agility=2: 100 - 24 = 76 tons external load (3x 24 ton Boxes)
• 5G, Agility=2: 80 - 24 = 56 tons external load (2x 24 ton Boxes)
• 6G, Agility=3: 66 - 24 = 42 tons external load
• 6G, Agility=4: 50 - 24 = 26 tons external load (1x 24 ton Box)
• 6G, Agility=5: 40 - 24 = 16 tons external load
• 6G, Agility=6: 33 - 24 = 8 tons external load

Short range due to life support endurance (acceleration couches only = 12-24 hours) ... which is "fine" when a craft is "tethered" to either a parent carrier or a base ... but it's not good enough for longer patrols needed by system defense to expand their sphere of operations to cover interplanetary transport lanes.

Solving the "short legs" phenomenon would require one major adjustment and a "tweak" to the external load limit assumption(s).



Without increasing the size of the hull (so as to keep the 24 tons form factor), what needs to happen is a reduction in the maneuver drive (from B to A) which will free up 2 tons of displacement inside the hull ... sufficient for a single small craft cabin, which can extend life support endurance beyond 24 hours.

However, that reduction in maneuver drive size/power will limit the maximum load capacity @ 1G to 200 combined tons.
But if fractions of 1G maneuver are an acceptable performance tradeoff (ala Annic Nova using "pinnaces" for maneuvering), it then becomes a question of where to "set" the external load towing capacity of the fighter small craft ... for both intended use cases as well as salvage and recovery operations.



Any "dead weight tonnage" of 100+ tons docked externally is going to follow Big Craft berthing rules (LBB5.80, p32), which means that as an external load a Big Craft "counts" as 110% of its "actual" tonnage.

• 100 ton Type-S Scout/Courier "counts" as 110 tons of external load
• 200 ton Type-A Free/Far Traders "count" as 220 tons of external load
• 400 ton Type-M Subsidized Merchant or Type-T Patrol Cruiser "counts" as 440 tons of external load
• etc. etc. etc.

So if a small craft (such as this fighter design) is meant to be able to dock with and "maneuver tow" a Dead Hulk™ of a Big Craft, it's going to need sufficient external load capacity to be built into its hull from construction (can't be retrofitted later). But where to "set" the threshold for that maximum external load capacity such that it's a "useful without being excessive" value?

The obvious breakpoints are @ 200 tons and 400 tons worth of Big Craft ... which compute out to being 220 tons and 440 tons of external load capacity just for those displacements. However, if you're dealing with a salvage/rescue type situation, you're probably going to want some additional external load margin so that the fighter can "bring with it" 1x 24 ton Box (@ 4G, Agility=4) which can be loaded with crew+equipment so the salvage operation can be a success.

• 440 + 24 = 464 tons of external load capacity "needed" for boarding operations onto and external load towing of a 400 ton big craft

So with those design constraints in mind, a slight redesign of the 24 ton fighter for a broader mission capability set then shakes out like so:



Fighter Provincial (Type-FP, TL=9)
24 ton small craft hull, configuration: 1 (MCr2.88, integral fuel scoops)
0 tons for Armor: 0 (TL=9, Composite Laminates, bulkhead thickness=20cm)
1 ton for LBB2.81 standard Maneuver-A (Agility=6 requires 1.44 EP @ 24 tons) (MCr4)
10 tons for LBB2.81 standard Power Plant-C (EP=6) (MCr24)
0.2 tons for Jump Capacitors (7.2 EP storage) (MCr0.8)
1 ton for fuel (5d 18h 09m endurance @ 3.44 EP output+basic power continuous) (basic power only consumes 0.012 tons of fuel per 7d)
4.8 tons for bridge (2 crew acceleration couches, life support endurance: 12-24 hours) (MCr0.12)
3 tons for model/3 computer (EP: 1) (MCr18)
1 ton for triple turret: pulse laser, pulse laser, pulse laser (TL=9, batteries: 1, code: 2, EP: 3) (MCr2.6)
* External Docking: 464 tons capacity (MCr0.928)
2 tons for 1x Small Craft Cabin (MCr0.05)
1 ton for cargo hold

• 1 ton capacity segregated reserve internal demountable fuel tank (MCr0.001)

= 0+1+10+0.2+1+4.8+3+1+2+1 = 24 tons
= 2.88+0+4+24+0.8+0.12+18+2.6+0.928+0.05+0.001 = MCr53.379

• 0.4G, Agility=0: 488 - 24 = 464 tons external load (400 ton Big Craft + 1x 24 ton Box)
• 1G, Agility=1: 200 - 24 = 176 tons external load (7x 24 ton Boxes) (100 ton Big Craft + 2x 24 ton Boxes)
• 2G, Agility=2: 100 - 24 = 76 tons external load (3x 24 ton Boxes)
• 3G, Agility=3: 66 - 24 = 42 tons external load
• 4G, Agility=4: 50 - 24 = 26 tons external load (1x 24 ton Box)
• 5G, Agility=5: 40 - 24 = 16 tons external load
• 6G, Agility=6: 33 - 24 = 8 tons external load

That looks like it'll "play" better On The Frontier ...

 

[Silverhawk]

There is a big discrepancy between potential output going to the jump drive and the required capacitor for jump itself, indicating the jump drive converts at least some of that fuel into a power surge.

Agreed. So here's how I see it. The power requirement to break the barrier between Jumpspace and N-Space is huge. This requires a power level of immense proportion at the instant of crossover. But once your in Jumpspace there is a field maintenance requirement which the power plant can handle but requires more than just 'keeping the lights on'.

My apologies for jumping back to another topic but I have been overloaded with RL and couldn't response at the time.
The idea of onboard fuel transfers between mother and daughter craft likely can go both ways. The daughter craft likely needs to have fuel in it to be ready to launch. But I would expect that you don't want it fueled while there is maintenance being done. Having the fueling system be able to go in either direction makes sense then. The pump isn't really going to care and the rest are just pipes and valves to direct the flow through the pump correctly.

 

[Spinward Flow]

Agreed. So here's how I see it. The power requirement to break the barrier between Jumpspace and N-Space is huge. This requires a power level of immense proportion at the instant of crossover. But once your in Jumpspace there is a field maintenance requirement which the power plant can handle but requires more than just 'keeping the lights on'.

It then becomes a simple matter of accounting ... whether the "maintenance for the duration" fuel cost is accounted for in the jump fuel requirement, or if the maintenance of the jump bubble fuel cost comes from the power plant fuel requirement. For reasons of simplicity, my perspective is that the jump fuel requirement covers the entire operation of the jump drive during the "week" in jump.

My apologies for jumping back to another topic but I have been overloaded with RL and couldn't response at the time.

Quite acceptable.
RL happens (just not for everyone ... ).

The idea of onboard fuel transfers between mother and daughter craft likely can go both ways. The daughter craft likely needs to have fuel in it to be ready to launch. But I would expect that you don't want it fueled while there is maintenance being done. Having the fueling system be able to go in either direction makes sense then. The pump isn't really going to care and the rest are just pipes and valves to direct the flow through the pump correctly.

My default assumption is that if the berthing space is defined as a "hangar" (costing Cr2000 per ton, as per LBB5.80, p32), then the fuel transfer between parent/daughter craft is something of a no brainer in terms of capability (capacity for storage when moved is a different problem).

 

[Silverhawk]

It then becomes a simple matter of accounting ... whether the "maintenance for the duration" fuel cost is accounted for in the jump fuel requirement, or if the maintenance of the jump bubble fuel cost comes from the power plant fuel requirement. For reasons of simplicity, my perspective is that the jump fuel requirement covers the entire operation of the jump drive during the "week" in jump.

It has always seemed to me that everything dealing with ships in Traveller regardless of version (some more than others ). That said, I advocate that it is the GM's responsibility to fix the 'accounting rules' from the beginning. You want to use the 10Pn fine. Something like Beltstrike or Book 5 that's okay too. But you better stick to it when someone thinks they have found a way around it.

And if you're playing for a GM who has set the rule differently then you accept that and play on.

My default assumption is that if the berthing space is defined as a "hangar" (costing Cr2000 per ton, as per LBB5.80, p32), then the fuel transfer between parent/daughter craft is something of a no brainer in terms of capability (capacity for storage when moved is a different problem).

That has always been my interpretation. I cannot see a hanger not having the basic needs to handle the craft that would be berthed there. Now, someone says I can get X in there because the size is Y then there might be a problem.

Of course a GM needs to be clear about the capabilities of the hanger at the start. Unless you're a really devious GM.

 

[Spinward Flow]

You want to use the 10Pn fine. Something like Beltstrike or Book 5 that's okay too. But you better stick to it when someone thinks they have found a way around it.

This is why I "decouple" the construction requirements from the rate of fuel consumption.
LBB2.77/81 using a 10Pn fuel tankage requirement for CONSTRUCTION works out "just fine" in the long run (all things considered).
LBB5.80 using a 0.01MPn fuel tankage requirement for CONSTRUCTION also works out "just fine" in the long run as well.

Both are basically "first order approximations" that ought to yield sufficient flexibility in "nominal operations" that you probably aren't going to need to worry (too much) about fuel starvation unless Something Bad Happens™. As a construction requirement, it's not trying to cover 100% of edge cases ... but rather be adequate for 90% of "ordinary" use cases. It's more of a "good enough for government contracting work" type of deal.

LBB2.77/81 and LBB5.80 made power plant fuel consumption so fungible as to be almost meaningless. Because the systems are different (10Pn vs 0.01MPn) direct comparisons are almost a case of "animal vs vegetable" in terms of implications and conclusions simply because the paradigms that underpin them don't agree on all that much. So fuel CONSUMPTION was a "mess" ... but the requirements for CONSTRUCTION worked just fine.

Bring in CT Beltstrike with its "backwards compatible to LBB2" fuel consumption formula and you can start building a complete picture. Beltstrike was one of the first Traveller products in which LIVING IN SPACE for extended durations of time (i.e. more than 2 week blocks of time for interstellar tramp merchant ops) because one of the controlling factors of logistics for survival which could then determine mission endurance before needing to return to base for resupply. The beauty of the CT Beltstrike fuel consumption formula is that it IS compatible with BOTH LBB2.77/81 AND LBB5.80 drive system paradigms, while simultaneously making it possible to do the necessary "fuel (and life support) accounting" for small craft and (non-)starships that undertake long duration voyages in normal space. It provides the necessary framework to start getting a better handle on how long a craft (such as a Type-S Scout/Courier and/or Type-J Seeker modification) can stretch its fuel load over a mission which could potentially take MONTHS (plural!) to complete ... whether that be an IISS Survey assignment or a private prospecting tasking.

In normal space, the power plant fuel consumption rate is going to vary somewhat widely depending on what you're needing to do with your craft. Stationkeeping close to an object of interest (such as an asteroid/planetoid) while prospecting places a very different demand load profile on a power plant+maneuver drive than undertaking a continuous acceleration/deceleration burn of thrust between planets in different solar orbits.

The CT Beltstrike fuel consumption formula does an excellent job as a "grand unified theory" of how fuel is CONSUMED without needing to make any statements about how large fuel tanks need to be when a craft is CONSTRUCTED. Working out how long a craft can "endure" operating at various rates of fuel consumption (inertial cruising @ zero acceleration vs rapid transfer @ max acceleration) then becomes a sort of mini-game for operators of craft in space, where the tradeoffs basically boil down to time vs fuel (and how quickly one can be exchanged for the other). There's still a touch of "rocket equation" type stuff going on, but it's relatively simple and doesn't require excessive amounts of INT or EDU stats to work things out (using simple arithmetic and a calculator).

The CT Beltstrike fuel consumption formula also makes it possible to "structure activities" in ways that are more fuel conservation efficient/wasteful depending on circumstances ... something that LBB2.81 and LBB5.80 find it hard to accomplish, short of inflicting battle damage.

 

[Spinward Flow]

For full transparency, I've posted my "reinterpretation" of the CT Beltstrike fuel consumption formula that is mathematically backwards compatible with LBB2, but redone to make things easier/simpler when working with a LBB5.80 paradigm that relies on Energy Points (EP).

7 days of fuel consumption (tons) = (Hull Tonnage / 2000) + (EP * 0.35)

So a 2000 ton hull requires 1 ton of fuel consumption per 7 days/1 week for Basic Power (what I like to think of as housekeeping). This is essentially your life support (lights, atmospheric recirculation, etc.) along with keeping the heat pumps running (L-Hyd fuel remains cryo chilled so it doesn't boil off, inhabited spaces remain "shirtsleeves warm" for passengers and crew) as well as whatever other various and sundry plumbing and services need "power" to stay operational.

EPs are used for maneuver drives, computers, weapons and screens.
Producing 1 EP for 7 days costs 0.35 tons of fuel.



Plug in values for a 100 ton Type-S Scout/Courier and you get:

• (100/2000) + (2*0.35) = 0.75 tons of fuel consumption per 7 days @ 2 EP output from Power Plant-A drive
• (100/2000) + (1*0.35) = 0.40 tons of fuel consumption per 7 days @ 1 EP output from Power Plant-A drive
• (100/2000) + (0*0.35) = 0.05 tons of fuel consumption per 7 days @ 0 EP output from Power Plant-A drive

The formula works for "everything" from small craft to million ton tenders.



And just to be even clearer, my "research" into the Modular Box containerization system (in this thread) is predicated upon the notion that the Boxes are (natively) "unpowered" because they do not have a power plant (of any size) installed into them. So instead, the Basic Power requirement for any and all Boxes needs to be supplied by the "parent" transporting craft ... whether that be a small craft or a big craft (or a hangar/starport berth).

So if a 24 ton Box (any type) is docked to a 24 ton Fighter Escort, for example ... the Basic Power requirement for the combination is 48 tons of hull (obviously) which needs to be "paid for" out of the Fighter Escort's fuel reserves, in addition to whatever EP generation is going on.

Likewise, a 280 ton starship with 4x 24 ton Boxes docked externally to it has a Basic Power requirement of a combined 280+24*4=376 tons of hull ... not just 280 tons of starship hull. However, if those same 4x 24 ton Boxes are loaded internally into a hangar (or cargo) bay, with no external load(s) docked to the exterior ... then the Basic Power requirement is calculated using the 280 tons of the starship's hull.

Point being that "there's no free lunch" when it comes to the amount of tonnage requiring Basic Power ... and the more tonnage you have (or need to support), the higher the fuel consumption (per week) to maintain nominal operating conditions for that tonnage.

 

[Ulsyus]

It then becomes a simple matter of accounting ... whether the "maintenance for the duration" fuel cost is accounted for in the jump fuel requirement, or if the maintenance of the jump bubble fuel cost comes from the power plant fuel requirement. For reasons of simplicity, my perspective is that the jump fuel requirement covers the entire operation of the jump drive during the "week" in jump.

I just had a look in LBB5.80, p23 provides:

FUEL REQUIREMENTS
Jump Drive: 10% of ship size in tons per jump number of ship capability. This allowance supplies fuel for one jump of that number.
Power Plant: One ton per energy point produced. This allowance supplies four weeks of activity on both the maneuver drive and the power plant.

Jumping (sic) forward, T5.10 Book 2 p111 provides:

JUMP DRIVES
The key to the stars is the jump drive: an almost magical technology that shifts a ship through a tear in the fabric of spacetime into an alternate universe where the generally accepted laws of physics don’t apply. Jump involves some logical disconnects:
• vast amounts of power are required to transition to jump space, but almost no power is required to move through it

Just to see what the difference was I had a look at T5.09, p319;

Jump Fuel. Fuel equal to 10% of Hull times the Jump in parsecs is required at the initiation of Jump.

I don't have LBB2.81, only the 77 version, but 15 there provides;

At a minimum, ship fuel tankage must equal 0.1MJn+10Pn, where M is the tonnage of the ship, Jn is the ship's jump number, and Pn is the ship's power plant rating. Power plant fuel under the formula (10Pn) allows routine operations and maneuver for four weeks. Jump fuel under the formula (O.1MJn) allows one jump of the stated level. Ships performing jumps less than their maximum capacity consume fuel at a lower level based on the jump number used.

So it looks to be that fuel required for a jump is consumed in the process of making it, while the fuel required for power plant ops over the four weeks basic period is quite separate. Or have I missed your point?

 

[Spinward Flow]

So it looks to be that fuel required for a jump is consumed in the process of making it, while the fuel required for power plant ops over the four weeks basic period is quite separate. Or have I missed your point?

Yes and no.
The power plant fuel construction requirement (LBB2, LBB5, T5 et al.) is intended, as a game mechanic, to "ballpark" how much fuel ought to be sufficient for 4 weeks (minimum) of operation. The "problem" is that the construction system oversimplifies the answer to a degree that "is not useful" when needing to answer questions of LONG endurance beyond a single block of 2 weeks of time (the nominal interstellar merchant cadence of the tramp business).

For example ...

1. If I were to land a starship on a planet with a corrosive atmosphere (code: B) and just "park" there for 4 weeks ... how much fuel would my power plant consume for the duration?
2. If I were to undertake a Grand Tour of Flybys of planets in a star under continuous (full) acceleration ... how much fuel would my power plant consume for the duration?

Obviously, these are two very different "demand load" scenarios for power.
Option 1 is a Basic Power only scenario.
Option 2 is a Basic Power + "EPs" for Acceleration scenario.

If we oversimplify (to the point of absurdity) ... we would say that because of the RAW (including the ones you have cited) say "4 weeks" in the construction rules, the fuel consumption rate for Options 1 and 2 are EQUAL ... which is obviously nonsensical. It's like saying that trickle power and full power demand loads are exactly the same, when we know that they're not.

The construction rules for fuel tankage requirements need to account for Option 2 because it is the higher demand load ... but cannot account for Option 1, because it is the minimal demand load.



A better way to read the fuel tankage requirements in the construction system is that the minimum fuel requirements are meant to "ballpark" how much fuel ought to be sufficient for at least 1 jump plus some reserve to reach a refueling point before your fuel tanks run dry ... at which point a rescue/salvage operation is necessary. The phrase "4 weeks" is chosen (game mechanically) to provide sufficient margin of safety to handwave away any concerns while operating at a nominal 1 jump per 2 weeks cadence, making ACTUAL fuel consumption rate something of a non-issue as far as operational accounting is concerned (you never get more than half down and always have at least a 50% reserve).

The point is that the "4 weeks" endurance number is more of a You Must Be This High To Ride This Ride type of benchmark, rather than something you can use to reverse engineer fuel consumption rates from (because power plants are just *ON* at full blast, continuously, regardless of the demand load from other systems). You need an actual consumption rate formula to determine how much fuel you are USING in a variety of operational scenarios (anything from "sipping tea with the queen" up to "gulping as fast as you can chug-a-lug") due to varying demand loads at different times.

After all, if you saw a You Must Be This High To Ride This Ride sign ... would you assume that EVERYONE riding that ride was EXACTLY that height (and no taller)?
I wouldn't.
And I would hope that you wouldn't either ...

Or to put it another way ... how long can you idle your petroleum product fueled ground car for, compared to how long you can drive it at highway speeds? The fuel tankage is exactly the same, but the fuel consumption rate due to the difference in demand load for power output is completely different. I would not expect the idle time endurance to be exactly equal to the highway driving endurance ... and I suspect that you wouldn't expect the fuel consumption rates to be the same in both contexts either.

 

[coliver988]

While I do agree with the fuel usage as summarized by Spinward above, I can also see an alternative that does go against Beltstrike usage rules. Which I may not have, but based on the initial 3 LLBs, what if the power plant just outputs the same power regardless of usage? Similar to the pre-jump controller where you used ALL jump fuel in a jump regardless of actual distance? E.g., you have a jump-2 ship but only do a jump 1? I believe the original rules you used up all 20 (for a 100 dTon ship) tons, not just 10 as per later rules.

Just tossing that out there as something to consider as well.

And as a side note, I found that the high-end drag racers go through a LOT of fuel just idling:

A drag car, particularly a Top Fuel engine, can consume approximately 30 liters per minute (L/min) of fuel during idle. This high consumption rate is due to the engine's design and the specific fuel used in drag racing

 

[kilemall]

While I do agree with the fuel usage as summarized by Spinward above, I can also see an alternative that does go against Beltstrike usage rules. Which I may not have, but based on the initial 3 LLBs, what if the power plant just outputs the same power regardless of usage? Similar to the pre-jump controller where you used ALL jump fuel in a jump regardless of actual distance? E.g., you have a jump-2 ship but only do a jump 1? I believe the original rules you used up all 20 (for a 100 dTon ship) tons, not just 10 as per later rules.

Just tossing that out there as something to consider as well.

And as a side note, I found that the high-end drag racers go through a LOT of fuel just idling:

A drag car, particularly a Top Fuel engine, can consume approximately 30 liters per minute (L/min) of fuel during idle. This high consumption rate is due to the engine's design and the specific fuel used in drag racing

I would tend to go to always on for the letter drives and manual fuel use for the custom LBB5 drives. Letter drives being more rough and serviceable everywhere, custom drives providing more value but tethered to their TL starport.