New Jump Fuel House Rules - Tell Me What You Think!

[Solomani666]

From The Traveller Rule Book:

1. The power plant supplies the power to the jump engines to create the singularity needed to enter jump space. (i.e. jump dimming and the 'divert power' task check.)

2. Jump fuel is used to expand the jump space bubble around the ship.

3. All normal jumps last aproximately 1 week, so the jump bubble needs to be maintained for the same amount of time reguardless of the jump distance.


Since the power plant supplies the power to the jump engines and jump fuel is used primarily to expand the jump bubble and all jumps take the same amount of time, then why does a jump-2 take twice the jump fuel as a jump-1?


Hence I am considering the following house rules:

1. All jumpdrive, powerplant, and maneuver drive ratings stay as written.

2. Power plant fuel consumption stays as written.

3. All jumps regardless of distance expend only the jump fuel as specified for a jump-1. [Example: A Type S Scout Ship can now make two succesive jumps of one or two parsecs before refueling.]

4. Only the powerplant fuel need be refined for a safe jump.

5. All ships are now assumed to have separate jump and power supply fuel tanks with (normally closed) valves leading to each other.


This idea first came to me because it is 'impossible' to create a jump-6 starship under 1000 tons using the current rules. (Thus fracking up my characters business model to create "Imperial Express")

Let me know what you think.

Like all 'heretics', I await the torches and pitchforks!

 

[rust]

No torches and pitforks, just my remark already posted in the other
thread: You could just as well go the entire way, forget about jump
drives and use the optional hyperdrive, which would seem less com-
plicated to me.

 

[Egil Skallagrimsson]

No torches and pitforks, just my remark already posted in the other
thread: You could just as well go the entire way, forget about jump
drives and use the optional hyperdrive, which would seem less com-
plicated to me.

Agree with Rust, if you don't like the fuel expenditure go for hyperdrive.

But do note that with HG additions you can build j6 ships, even down to 100t, if you can afford them.

Torches and pitchforks, so TL1, I'm off to get my PGMP,

Egil

 

[CosmicGamer]

Tweaks have consequences. Some are not always obvious. The first one that jumps out at me is trade economics. If I'm getting it correct, a J4 now takes 1/4 the fuel? That is a nice fuel cost savings and reduces expenses. Now add in that there is more space for cargo. This fuel change may make it such that there is no reason to find patrons and take those side jobs anymore since trading is so profitable.

 

[DFW]

5. All ships are now assumed to have separate jump and power supply fuel tanks with (normally closed) valves leading to each other.

Never seen this otherwise in MGT rules.

That being said, you are changing a massive amount of assumptions. It will greatly change the TU for your game. Not good or bad, just a reality.

 

[rust]

Tweaks have consequences. Some are not always obvious. The first one that jumps out at me is trade economics. If I'm getting it correct, a J4 now takes 1/4 the fuel? That is a nice fuel cost savings and reduces expenses. Now add in that there is more space for cargo. This fuel change may make it such that there is no reason to find patrons and take those side jobs anymore since trading is so profitable.

Quite true. My way to reduce (not solve) the problem when I began to
use the hyperdrive was to increase the distances involved, for example
by making each hex of the subsector map fifteen parsec instead of one
parsec (or whatever is needed to allow the traders only one planetfall
per month) - the traders need to pay less for fuel and can transport mo-
re goods, but they have to spend more time in hyperspace and can buy
and sell goods less often, so the trade income remains unchanged.

 

[BP]

... it is 'impossible' to create a jump-6 starship under 1000 tons using the current rules.

Not correct.

... (Thus fracking up my characters business model to create "Imperial Express")

Correct.

That is why the rules are as written - you can make smaller J-6 ships - just don't expect to be hauling cargo, passengers or troops (or even possibly manuever ).

... Let me know what you think.

Nothing wrong - nothing original here either.

This is mostly a settings issue - its not really a game mechanics balance issue. Might have some very minimal impact on merchant rules. Impact to existing ship designs would also be minimal (assuming they just had more jumps for a fillup).

The original (CT) rules make it a tradeoff of range for other capabilities (trade) and were balanced against the fact that the random system generation rules rarely create a need for greater than J-4.

Basically, your rules make cost a greater difference for longer range vessels (versus other tradeoffs). 'Logically' that means the big boys have more of an edge in the smaller vessel trade/transport business - instead of a more even playing field with the little guys in which they all share the capacity vs range challenge.

However, its a game - if you want 400 ton J-6 far traders make it happen. If you want to 'blend' with existing material (leaving normal far traders in the dust) - just make the stuff available to players (and maybe select others) be 'enhanced/alternate J-Drives'.

 

[Solomani666]

No torches and pitforks, just my remark already posted in the other
thread: You could just as well go the entire way, forget about jump
drives and use the optional hyperdrive, which would seem less com-
plicated to me.

Agree with Rust, if you don't like the fuel expenditure go for hyperdrive.

But do note that with HG additions you can build j6 ships, even down to 100t, if you can afford them.

Torches and pitchforks, so TL1, I'm off to get my PGMP,

Egil

Please give an example of a 200 ton HG ship with J-6 capability.

 

[DFW]

Please give an example of a 200 ton HG ship with J-6 capability.

Hint. Use max TL for PP, JD & MD. Small bridge, etc.

 

[BP]

...
Please give an example of a 200 ton HG ship with J-6 capability.

That could be done, but would require unusual TLs I believe

J-6 drives are TL 15 and PP TL lower tonnage requires TL 15+, IIRC - so to make it work, one would probably need TL 18 drives! That after stripping away everything non-essential and using compact bridge, etc. to have enough space for the minimal PP fuel...

 

[DFW]

PP TL lower tonnage requires TL 15+, IIRC - so to make it work, one would probably need TL 18 drives! That after stripping away everything non-essential and using compact bridge, etc. to have enough space for the minimal PP fuel...

TL 15 PP's are 75% normal volume. TL 12 MD's are 75% volume.
pg. 53 HG.

Scout book has example of a bridge that is smaller than small bridge in HG using higher # computer also. (Optional if YTU uses real world chemistry) In addition, use H2O for PP fuel tanks instead of H2. This lowers volume requirements by ~40% vs. L-Hyd.

 

[Egil Skallagrimsson]

No torches and pitforks, just my remark already posted in the other
thread: You could just as well go the entire way, forget about jump
drives and use the optional hyperdrive, which would seem less com-
plicated to me.

Agree with Rust, if you don't like the fuel expenditure go for hyperdrive.

But do note that with HG additions you can build j6 ships, even down to 100t, if you can afford them.

Torches and pitchforks, so TL1, I'm off to get my PGMP,

Egil

Please give an example of a 200 ton HG ship with J-6 capability.

The example I was thinking of is the "100 ton XPS6 Mustang" on page 79 of the Scout book. I'm not about to put the full details on here (buy the book yourself), but suffice to say it uses a drop tank and some uprated technology (and some HG options). As far as I can see the design works. Of course, you would only get one jump 6 unless you jump into a system where another drop tank will be available.

Suggest you direct your players towards a jump 4 courier service instead.

Egil

 

[Egil Skallagrimsson]

Might have some very minimal impact on merchant rules. Impact to existing ship designs would also be minimal (assuming they just had more jumps for a fillup).

Agree with the rest of your post, BP, but think that just leaving all that fuel space as a "fillup" would be very unlikely, the merchants would want it as cargo or passenger space, the military as extra armour and weapons, not redisigning the ships would be a bit of a cop out.

Egil

 

[BP]

Good point Egil - however, that paragraph started with: 'This is mostly a settings issue - its not really a game mechanics balance issue'.

Was merely pointing out that the game mechanics weren't broken by the idea - logically, within a setting (notably the OTU), it might not make very much sense.

 

[hdan]

Since the power plant supplies the power to the jump engines and jump fuel is used primarily to expand the jump bubble and all jumps take the same amount of time, then why does a jump-2 take twice the jump fuel as a jump-1?

I'm happy with the current system, personally.

The way imagine it, each level of jump pushes our ship one "deeper" into J-space, which is increasingly hostile to matter and ablates the "jump bubble" at a higher rate. Thus you need a bigger bubble for faster transit.

The jump bubble protects the ship, and is just enough extra matter be annihilated in the week the ship takes to "bob back up". You can always pump out more hydrogen (which will flare off on re-entry into the universe), but less hydrogen will just result in parts of your ship evaporating (or more likely your re-entry being skewed so badly that it fails, since your hull is not refined hydrogen).

In your system, maybe you would decide that the jump bubble does not evaporate.


Though another less-canonical explanation I'm toying with is this:

The energy of the ablated hydrogen as channeled by the jump field is used to propel the ship. The J-drive draws power the whole time you are in jump (else you wouldn't need a matching power plant) and uses that power to maintain the jump field, which contains and guides the hydrogen during the jump. Higher tech drives can generate more sophisticated field geometries to configure the jump field so that they can "burn" the fuel bubble harder for a faster transit. (That's how I justify the fact that some drive/hull combinations should be able to achieve jumps beyond their tech level. Yes, they have the POWER to do that, but not the sophistication.)

 

[Egil Skallagrimsson]

Good point Egil - however, that paragraph started with: 'This is mostly a settings issue - its not really a game mechanics balance issue'.

Was merely pointing out that the game mechanics weren't broken by the idea - logically, within a setting (notably the OTU), it might not make very much sense.

Like I said, BP, agreed with the rest of the post, and understood the paragraph, just thought your suggestion, commenting about the likely effects of the rule suggestion, was not the best.

Egil

 

[Egil Skallagrimsson]

Since the power plant supplies the power to the jump engines and jump fuel is used primarily to expand the jump bubble and all jumps take the same amount of time, then why does a jump-2 take twice the jump fuel as a jump-1?

I'm happy with the current system, personally.

The way imagine it, each level of jump pushes our ship one "deeper" into J-space, which is increasingly hostile to matter and ablates the "jump bubble" at a higher rate. Thus you need a bigger bubble for faster transit.

The jump bubble protects the ship, and is just enough extra matter be annihilated in the week the ship takes to "bob back up". You can always pump out more hydrogen (which will flare off on re-entry into the universe), but less hydrogen will just result in parts of your ship evaporating (or more likely your re-entry being skewed so badly that it fails, since your hull is not refined hydrogen).

In your system, maybe you would decide that the jump bubble does not evaporate.


Though another less-canonical explanation I'm toying with is this:

The energy of the ablated hydrogen as channeled by the jump field is used to propel the ship. The J-drive draws power the whole time you are in jump (else you wouldn't need a matching power plant) and uses that power to maintain the jump field, which contains and guides the hydrogen during the jump. Higher tech drives can generate more sophisticated field geometries to configure the jump field so that they can "burn" the fuel bubble harder for a faster transit. (That's how I justify the fact that some drive/hull combinations should be able to achieve jumps beyond their tech level. Yes, they have the POWER to do that, but not the sophistication.)

Now, these are two examples of quality, top notch, handwavium!

Egil

 

[hdan]

Now, these are two examples of quality, top notch, handwavium!

Thank you, kind sir. My hands are a bit worn out after that excercise.

 

[AlphaWhelp]

Came in here to suggest a middle ground between crazy Jump fuel requirements and ridiculously overpowered Hyperspace drive.

Using Energy Efficiency rules from Signs & Portents, and a Warp Drive, you can traverse the galaxy significantly slower than a Hyperspace drive, while at the same time not requiring copious amounts of fuel. In fact, travel time will remain roughly the same as it would with a Jump drive if you didn't need to stop and refuel and process hundreds of tons of fuel after every jump.

For example, at TL14, 400 ton ship with a Power Plant & W-Drive M can travel at Warp-6 for 25 weeks on 24 tons of fuel before needing a 25th ton of fuel.

If this is too little fuel, then just don't use energy efficiency, Warp drives still use way less fuel than Jump. The same ship above simply travels at Warp-6 for one week on 24 tons of fuel, Warp-6 for two weeks on 48 tons of fuel, and so on.

 

[Egil Skallagrimsson]

Came in here to suggest a middle ground between crazy Jump fuel requirements and ridiculously overpowered Hyperspace drive.

Using Energy Efficiency rules from Signs & Portents, and a Warp Drive, you can traverse the galaxy significantly slower than a Hyperspace drive, while at the same time not requiring copious amounts of fuel. In fact, travel time will remain roughly the same as it would with a Jump drive if you didn't need to stop and refuel and process hundreds of tons of fuel after every jump.

For example, at TL14, 400 ton ship with a Power Plant & W-Drive M can travel at Warp-6 for 25 weeks on 24 tons of fuel before needing a 25th ton of fuel.

If this is too little fuel, then just don't use energy efficiency, Warp drives still use way less fuel than Jump. The same ship above simply travels at Warp-6 for one week on 24 tons of fuel, Warp-6 for two weeks on 48 tons of fuel, and so on.

Personally I have no problem with the restrictions that the fuel requirements of jump drive involve, it creates a certain kind of dynamic, trade etc., perhaps with a comparatively "slow" kind of FTL (you're still travelling several light years in one week, pretty safely, which is impressive enough!)

Not sure that hyper space drive is over powered, just different. If the 3I setting used hyper drive then it would be very different, probably much larger, and much more centralised.

The alternative drives just don't fit with 3I, but, that's not a problem. If you design your own universe, then other drives might well fit your ideas best.

Egil