I have been pondering halving the Jump Fuel requirement.

[infojunky]

Ok, consider this, most commercial ships refuel about once a month. The power plant fuel is rated for a month. Why not have the Jump Fuel refill at the same rate when using the standard week between jumps schedule.

 

[Spinward Flow]

The power plant fuel is rated for a month.

That's a Safety Margin Requirement.

Aviation instructors will teach you that there are 3 things in aviation that are COMPLETELY USELESS TO YOU regardless of how much you have of them you have:

1. Altitude above you.
2. Runway behind you.
3. Fuel in the truck.

It's #3 that is most relevant to the point you're raising, @infojunky.

Under "generic/nominal" circumstances, you're going to spend a week in jump and a week in normal space as a tramp free trader, so you're working on a 2 jumps per month tempo a lot of the time. The reason why the 4 weeks of power plant fuel endurance is required for starships comes down to ... MARGIN. You want to have plenty of margin and reserve fuel available in the event of a mishap, a casualty (such as a collision or battle damage) or other "unplanned event" occurring during your travels. That reserve is there to KEEP YOU ALIVE ... because without fuel, your starship is a very expensive COFFIN™.

So think of the 4 weeks requirement for starships as being something more akin to a standard emergency reserve, rather than something you're going to be constantly burning through (down to nothing) before you refuel.

Fuel in the truck ... is useless to you, no matter how much fuel is in that truck.
If the fuel isn't in your ship (or attached to your ship somehow), you can't use it.

Better (read: safer!) to Have and Not Need ... than it is to Need and Not Have.

 

[Grav_Moped]

That's a Safety Margin Requirement.

Agreed. In-universe, it's probably a regulatory thing since it's not mechanically necessary. RAW mandates it, and if that's your benchmark it ends there.

I still don't see why an XBoat needs a month of power plant fuel when it (RAW LBB2'81) will only ever use 7.7 days worth, maximum, when used as designed. (Can't misjump if fed refined fuel, can't maneuver, has tanker support at both ends of a Jump, has no need to run the power plant at full power once out of Jump.)

As a game mechanic, the one-month allocation makes jump fuel the primary range/endurance constraint, so you don't have to bother tracking the power plant fuel. It's a reasonable enough simplification. I figure that corners can be cut if the players are willing to do some math...

 

[Spinward Scout]

I think it was a chart in T20 that changed/lowered Jump fuel for higher Tech Levels.

 

[Spinward Flow]

I still don't see why an XBoat needs a month of power plant fuel

They don't.
It was a regulatory waiver owing to the fact that XBoats are an extremely specialized starship class that isn't used for anything other than interfacing with Express Tenders.

Given the limitations on how XBoats operate as starships (jump only, no maneuver drive) there just isn't much of an opportunity for an XBoat to (intentionally) "go off the reservation" (so to speak) ... and if they do, it's pretty much going to be a one-way trip ... unless ... if it's the start of a story that opens like this ...

 

[McPerth]

Halving the Jump Fuel requirements has many implications that (IMHO) must be pondered before implementing or you’ll be facing the law of unintended consequences quite soon.

For commercial ships, how long until someone decides that instead of having the fuel for two jumps, it would be better to keep just for one jump and use the so “freed” space for cargo/passengers? Ship’s economics change quite a lot, if you can have a J4 ship that only needs 20% of its volume for fuel, or if you can have a J6 ship using “only” 30% your ship volume for fuel…Add to this the reduced fuel costs, and you’ll see many ships will become `profitable while with standard rules they are not.

As for military ships, allowing them two jumps while keeping their payload would make he “front lines” even more flexible and permeable. The fact you must jump from system to system due to fuel needs allow the “front lines” to be kept with some scouts at each system to warn the fleet of incoming enemies. If they no longer need it and can jump to mid-space and then jump again, a J4 fleet may strike without warning a system up to 8 parsecs away, so forcing you to garrison quite more planets and making defense quite more difficult, fully changing the strategies needed. Add to this the possible tanker use, and you’ll see how the “front lines” now engulf whole subsectors…

So, I think it would be quite setting breaking, changing it enough as to need for quite a thought. Is this good or bad? I guess each one of us will have his own answer to this…

 

[Condottiere]

When I calculated it out, you don't have enough space for batteries to operate basic systems onboard a starship for a week, and as far as I know, solar panelling doesn't pick up sun rays in jumpspace.

So you need that reactor for life support.

And I think MegaTraveller did tinker with fuel requirements.

 

[bookwyrm]

I think it was a chart in T20 that changed/lowered Jump fuel for higher Tech Levels.

No.

Jump Fuel Option Pg. 265 of The Travellers Handbook T20: For Referee's who who want to make Trade & Commerce more feasible, reduce jump fuel requirements by one-half.

@McPerth For the big picture, you are correct. But if you keep things in the small view... I've worked up some trade ships with jump 2 + jump 1 capability and jump 2 with lots more passenger and/or cargo space. For the first version, you won't always need to go 3 parsecs for every trip and for the second one, extra passenger & cargo space doesn't always mean you'll have a full ship, and the extra space you save for needing less fuel usually means a more expensive ship as you are probably putting more component on the ship that increases costs. So it's a trade off in the early game, but if players can make it to mid game with some credits, the extra range and passenger/cargo will eventually flood your pockets with incoming credits, which can bring another can of worms in the form of pirates or other situations that come with coming into lots of credits.

 

[kilemall]

Hmm I am now strongly considering going to this paradigm.

For gameplay setting reasons.

That’s because I have a strong delineation between the legitimate transport world and the pirate fueled underverse.

Pay full price and get secure cargo passenger delivery with inspected legit operators that fly with safety margin fuel and logged flight plans.

Or pay half price or less and get illegal cargo taken to shady transport to Oort Cloud jumps, ships that haven’t seen maintenance in over a year and likely will misjump or be discarded in favor of newly pirated craft, and transaction security bonded by the laser rifle you carry.

Safety margin fuel is another differentiator, a nice campaign doesn’t end cause misjump, still have fuel to get to closest system, and extra risk/reward for those doing business away from legit A/B/C starports.

Could even sneak in side trips in between legitimate two week cycle operations.

 

[Spartan159]

I have had 5% per jump number under consideration for some time. on the expanded Jump scale it makes Jump 7-9 a possibility for one. I have been tinkering with 7% per jump number also. Not sure yet on the effects of doing so.

 

[Spinward Flow]

on the expanded Jump scale it makes Jump 7-9 a possibility for one. I have been tinkering with 7% per jump number also.

Have you given any serious thought to 8% per parsec, instead of 10%?

• J1 = 8%
• J2 = 16%
• J3 = 24%
• J4 = 32%
• J5 = 40%
• J6 = 48%
• J7 = 56%
• J8 = 64%
• J9 = 72%

It certainly makes the J7-9 range "not as ridiculous" as 10% does.
Ironically, such a shift would mean that military ships would probably shift from a J4/6G standard performance maximum towards a J5/6G standard performance maximum.

 

[Dragoner]

I have played around with jump fuel a lot, and while I list it regular in play I general hand wave the bean counting aspect, and just say it's available or something. Players are still going to faff about on planets, or in stations, more leniency on fuel req's only increases their ability to do that. It is the more fun part of the game anyways.

 

[Grav_Moped]

When I calculated it out, you don't have enough space for batteries to operate basic systems onboard a starship for a week, and as far as I know, solar panelling doesn't pick up sun rays in jumpspace.

So you need that reactor for life support.

And I think MegaTraveller did tinker with fuel requirements.

Mongoose tried too hard on their take on the XBoat.
A larger power plant (and there's room for it, and for fuel) would let it charge its own jump capacitors.

MgT ships do not need (the equivalent of) Pn=Jn power for the whole Jump, just at initiation -- after that, it's just the baseline power requirement. CT (LBB2'81, and all LBB5) ships do need it, based on fuel burn rates.

 

[Condottiere]

You'd need a continuous charge, as well, if the lanthanum grid had to be powered on for a week.

Which in the MongoVerse, you don't.

It was one of the first things I had to have clarified.

I don't think it matters in previous editions on the fuel burn, as the power plant just permitted an overclocked amount of energy to be expended within two turns, and after that, it was just maintaining the jump field.

 

[mike wightman]

There is no Lanthanum hull grid (it was a DGPism that disappeared with MT) as has been pointed out many times. Lanthanum is used in the drive coils.

 

[Spartan159]

There is no Lanthanum hull grid (it was a DGPism that disappeared with MT) as has been pointed out many times. Lanthanum is used in the drive coils.

Well I guess T5 brought it back.

 

[Spinward Flow]

on the expanded Jump scale it makes Jump 7-9 a possibility for one. I have been tinkering with 7% per jump number also.

Here's a fun alternative to ponder.

• 0.08MJn per parsec of jump
• 0.02MPn per 28 days of power plant endurance

That adjustment both hews pretty closely to LBB5.80 fuel formulas, but has some rather interesting knock on consequences and edge cases when starship design starts getting really complex ... both on the low end (100 tons) and at the high end (30k+ tons).

 

[mike wightman]

Well I guess T5 brought it back.

Show me where it says there is a Lanthanum hull grid in T5.
There is a jump cable network in the hull, but only MT ever referred to it as a lanthanum grid.

 

[Spartan159]

Show me where it says there is a Lanthanum hull grid in T5.
There is a jump cable network in the hull, but only MT ever referred to it as a lanthanum grid.

You are quite correct sir. The grid in T5 was not detailed as to composition, may as well be Unobtanium or Omnesium as Lanthanum. Nothing saying it's not, either. What is the problem with it being Lanthanum or an alloy thereof? Just curious.

Here's a fun alternative to ponder.

• 0.08MJn per parsec of jump
• 0.02MPn per 28 days of power plant endurance

That adjustment both hews pretty closely to LBB5.80 fuel formulas, but has some rather interesting knock on consequences and edge cases when starship design starts getting really complex ... both on the low end (100 tons) and at the high end (30k+ tons).

Interesting, taken under consideration.

 

[RossWinn]

Ok, consider this, most commercial ships refuel about once a month. The power plant fuel is rated for a month. Why not have the Jump Fuel refill at the same rate when using the standard week between jumps schedule.

My question is why? Is there a specific reason that makes the game better, or is it just a way to put more stuff in a ship?
Yes, it is an arbitrary rule, but it has been canon in the setting since inception. Why change?