Jump Drive Efficiency Question

[Sifu Blackirish]

IMTU the progression of sizes and jump fuel usage is reversed. At TL9 a jump drive designed with HG takes 7% space, and takes 60% fuel to perform jump-1.

I took the time to rewrite the jump potential chart by TL and was surprised to see that with a 5000 ton ship, I can only achieve jump-1 at TL15.

Did I make a mistake in assuming that Book 2 drives use the same percentages as HG? That is
jump--1--2--3--4--5--6
%-----7--6--5--4--3--2

Comments are welcome and appreciated.

 

[mike wightman]

LBB2 uses a different drive paradigm to High Guard.

In LBB2 the jump drive is the largest component, where in HG the maneuver drive is the largest.

I still think that someone made a mistake with the drive percentage table in High Guard first edition, and it was never corrected

 

[robject]

I'm surprised. I thought jump drives always required 10% fuel per parsec jumped, regardless of tech level... well, assuming Classic Traveller or T4, that is...

It seems to me that your TL9 example would still only require 10% volume for jump fuel.

 

[parmasson]

I always wondered about that. Shouldn’t ten tons of jump drive at TL15 buy you more jump for your Credit then at TL10?
Just for sake of argument . . .

Free Trader
TL-10 Jump 1
TL-13 Jump 2
TL-15 Jump 3

 

[robject]

Perhaps. It might depend on what parts of the jump drive are improvable. They're not like conventional technology. But, we know there are areas where jump drive improvement, er, improves:

High tech (TL14+?) jump drives seem to be able to burn unrefined fuel.

Very high tech drives (TL16+) seem to work on ships under 100 tons (TNE?).

At least according to MT, fuel requirements are lower than CT. That guides me to decide that very high TL drives (16? 17?) have half the fuel requirement. That's an IMTU.

 

[daryen]

The important thing to remember is that Bk2 and Bk5 are completely different design systems, with different goals and underlying assumptions. While the rules do allow components to be used back and forth, they are very different in regards to the drives.

The two major assumption differences are:
1) As mentioned above, in Bk2 the jump drive component is the biggie; in Bk5 the maneuver drive component is the biggie. Unlike Sigg, I think they intentionally made the change and would have changed Bk2 if they thought they could.
2) TL requirements. In Bk2, TL limits the available modules regardless of capability. In Bk5 the actual capabilities are limited. So, in Bk2 you can build a J2 ship built at TL9 (the scout) and a J3 ship built at TL10 (the patrol cruiser); the J4 X-boat is only TL9. In Bk5, that is not possible. You need TL13 to build a J4 ship, regardless of size.

Trying to reconcile the Bk2 and Bk5 design systems will only lead to frustration. Don't bother; just pick a system and use it.

This is true for all of the systems. TNE is especially true in this regard. The TNE design system changed lots of things, not just jump fuel requirements. Quite frankly, the GT design system is closer to CT than is the TNE design system.

All jump drives may burn unrefined fuel. You just run an increased risk of misjump. To eliminate that risk, you need a fuel purifier (provided in Bk5 and later systems) or learn to buy refined fuel (in Bk2). Increased TL has no influence on this operation.

Increased TL has no affect on jump drive operation in any way. Drives never get any better. Sure, they can jump farther, but they don't operate any better or more effeciently. A TL9 J1 drive is in all ways identical to a TL15 J1 drive.

Jump fuel is also inconsistent across design systems. In Bk2, Bk5, T20, and GT it takes 10% of the hull volume in fuel. In MT and TNE it takes 5% plus another 5% per jump number. (This was done to compensate for the much higher power planet fuel requirements.) (I have no idea what T4 did.) Again, the fuel requirements don't change regardless of TL. So, (in CT or T20) a 200 dton ship needs 40 dtons of fuel for a 2 parsec jump. This is constant regardless of TL and regardless of what the actual jump rating of the drive is (as long as it is at least J2).

This is all OTU. Obviously, many people change things to suit them better. But the above is for the OTU.

 

[robject]

I agree with Daryen's opinion, that the drive changes in HG were intentional. I tend to also agree with Sigg in the opinion that it was not necessarily an improvement.

At least in CT, some jump drives are better than others -- in their ability to burn unrefined fuel with no risk. So we know there is some type of improvement; but perhaps in CT there's an implied front-end refinery in certain jump drives which doesn't take up much volume. In game terms, that's a "better" jump drive.

As for TNE, what I want to know is if any TL is allowed to build jump boats. Anyone know?

 

[mike wightman]

Originally posted by daryen:
The important thing to remember is that Bk2 and Bk5 are completely different design systems, with different goals and underlying assumptions. While the rules do allow components to be used back and forth, they are very different in regards to the drives.

Not only different design systems, but they create different game universes.
LBB2 is a small ship univers, where PC scale ships have some roll to play.
HG switches things to a big ship universe where a PC scale ship is a blip compared to the smallest true warship - by the latter I mean the multi kiloton stuff, not the sub-1000t escorts.

The two major assumption differences are:
1) As mentioned above, in Bk2 the jump drive component is the biggie; in Bk5 the maneuver drive component is the biggie. Unlike Sigg, I think they intentionally made the change and would have changed Bk2 if they thought they could.

They produces revised or second edition CT, The Traveller Book, and the Starter set all after printing and then revising High Guard.
The opportunity to bring one or the other game into line was there.
It's a conspiracy I tell yah

2) TL requirements. In Bk2, TL limits the available modules regardless of capability. In Bk5 the actual capabilities are limited. So, in Bk2 you can build a J2 ship built at TL9 (the scout) and a J3 ship built at TL10 (the patrol cruiser); the J4 X-boat is only TL9. In Bk5, that is not possible. You need TL13 to build a J4 ship, regardless of size.

Again, totally different univers paradigm.

Trying to reconcile the Bk2 and Bk5 design systems will only lead to frustration. Don't bother; just pick a system and use it.

Except there are canon designs that do mix the two

This is true for all of the systems. TNE is especially true in this regard. The TNE design system changed lots of things, not just jump fuel requirements. Quite frankly, the GT design system is closer to CT than is the TNE design system.

Yep, I agree.
Although TNE ships are easier to translate to GT using GT Starships and GURPS vehicles than they are to CT/HG/T20.

All jump drives may burn unrefined fuel. You just run an increased risk of misjump. To eliminate that risk, you need a fuel purifier (provided in Bk5 and later systems) or learn to buy refined fuel (in Bk2). Increased TL has no influence on this operation.

In LBB2 military and scout jump drives can use unrefinrd fuel with no penalty.

Increased TL has no affect on jump drive operation in any way. Drives never get any better. Sure, they can jump farther, but they don't operate any better or more effeciently. A TL9 J1 drive is in all ways identical to a TL15 J1 drive.

Unless you bring in the rules from MT where very high TL drives become more fuel efficient.

Jump fuel is also inconsistent across design systems. In Bk2, Bk5, T20, and GT it takes 10% of the hull volume in fuel. In MT and TNE it takes 5% plus another 5% per jump number. (This was done to compensate for the much higher power planet fuel requirements.) (I have no idea what T4 did.) Again, the fuel requirements don't change regardless of TL. So, (in CT or T20) a 200 dton ship needs 40 dtons of fuel for a 2 parsec jump. This is constant regardless of TL and regardless of what the actual jump rating of the drive is (as long as it is at least J2).

T4 used 10% per jump number too.
And as I said earlier, the jump fuel required is reduced at very high TLs in MT - but since MT is the only ruleset to ever detail the tech up to the games TL boundaries there is nothing to contradict it

This is all OTU. Obviously, many people change things to suit them better. But the above is for the OTU.

It can't all be for the OTU because it contradicts itself. You thus have an AOTU situation for each change of ship paradigm.
LBB2 1st edition OTU is different to LBB2 2nd edition is different to HG 1st edition OTU is different to HG 2nd edition OTU is different to MT OTU is different to TNE OTU is different from GT ATU is different from the T20 OTU.

It gives you a lot of choice I suppose

I agree with daryen earlier - pick the one you like and stick with it. You can always borrow bits from elsewhere if you can make them fit, and you can change anything you like in YTU

 

[mike wightman]

Originally posted by robject:
I agree with Daryen's opinion, that the drive changes in HG were intentional. I tend to also agree with Sigg in the opinion that it was not necessarily an improvement.

It's a conspiracy to cover up GDW's mistakes...

{joking}

At least in CT, some jump drives are better than others -- in their ability to burn unrefined fuel with no risk. So we know there is some type of improvement; but perhaps in CT there's an implied front-end refinery in certain jump drives which doesn't take up much volume. In game terms, that's a "better" jump drive.

It would have been nice if they had said that military drives cost a bit more or something.

As for TNE, what I want to know is if any TL is allowed to build jump boats. Anyone know?

The jump boat fiddle comes about because FF&S gives a minimum jump drive module size of 2m^3 at any TL.
I can't see anything that stops you building jump boats at any TL 9+.
TL9 maximum jump 1 2m^3 jump module can shift a 7dt ship through jump space.
TL11 jump 2 craft could be 4dt.
TL12 jump 3 craft could be 3dt.
TL13 jump 4 craft could be 2dt.
TL14 jump 5 craft could be 2dt.
At TL15 a 2m^3 jump 6 drive could move a 2dt "ship" - jump torpedos return

 

[mike wightman]

Here's the fuel efficiency progression from MT for very high TLs:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> TL fuel multiplier
9-16 x 1
17 x 0.8
18 x 0.6
19 x 0.4
20 x 0.2
21 x 0.1</pre>[/QUOTE]Use the normal jump fuel formula for your rule set and then multiply by the TL factor given above to arrive at actual jump fuel required.

 

[mike wightman]

So the TL16 world Vincennes invests heavily in civilian jump research and builds an experimental TL17 jump 6 engine.

After flight tests and calibration the engineers are delighted to find that the ship only requires 60% x 0.8 = 48% of its hull volume in jump fuel.

Elsewhere, in a secret military research station in the Vincennes system the black projects division has pushed jump tech all the way to TL18.
They can outfit a jump 6 ship that only requires 60% x 0.6 = 36% of its hull tonnage in jump fuel.

 

[Tobias]

Originally posted by Sigg Oddra:
Not only different design systems, but they create different game universes.
LBB2 is a small ship univers, where PC scale ships have some roll to play.

Which role? The role of PC ships only switches from being dwarfed by 100kton ships to being dwarfed by sky-darkening swarms of 2000-ton ships.

The opportunity to bring one or the other game into line was there.

It would have required a major rewrite of the rules and the published designs - something that didn't happen until MT.

Except there are canon designs that do mix the two

Which ones? Anyway, the fact that there are published errors doesn't make them less erroneous.
In any case, mixing HG and Bk2 usually takes the form of obvious cheating. Bk2 maneuver drives and HG jump drives in the same ship, anyone?

It can't all be for the OTU because it contradicts itself. You thus have an AOTU situation for each change of ship paradigm.

Well, it is obvious for one that the OTU is a "big ship universe" ever since it was beginning to be defined.

Regards,

Tobias

 

[mike wightman]

Which role? The role of PC ships only switches from being dwarfed by 100kton ships to being dwarfed by sky-darkening swarms of 2000-ton ships.

The 800t merc cruiser is a force to be rekoned with in a universe where 400t SDBs defend systems and the top of the line Imperial battle cruiser is the Kinunir, four of which are all that is needed to defend the Spimward Marches

It would have required a major rewrite of the rules and the published designs - something that didn't happen until MT.

You mean like tha major rewrite of High Guard first edition to produce sedond edition, or more like the major rewrite that produced second edition, or revised, CT in 1981 and then The Traveller Book and later Starter Traveller?

Which ones? Anyway, the fact that there are published errors doesn't make them less erroneous.
In any case, mixing HG and Bk2 usually takes the form of obvious cheating. Bk2 maneuver drives and HG jump drives in the same ship, anyone?

The Gazelle as originally presented in JTAS was armoured and equipped with PAWs, and the Kinunir, with its black globe and PAWs.

Well, it is obvious for one that the OTU is a "big ship universe" ever since it was beginning to be defined.

Yep, as the OTU was detailed it moved further from the original small ship universe - although TNE almost brought it back

 

[far-trader]

Originally posted by Sigg Oddra:
The jump boat fiddle comes about because FF&S gives a minimum jump drive module size of 2m^3 at any TL.

I'm still of a mind that the above was a gross and silly blunder and what was really meant was that the minimum size of a jump drive module was to be 2 tons at any TL (same as previous editions) but then when translating everything to m^3 nobody changed the number. And nobody fixed it in the errata either. Why? Because the ones who noticed didn't complain, they got their jump torps back and were thrilled

 

[mike wightman]

I like my jump torpedos

And if they admit to the FF&S blunder they'd have to admit the LBB2/HG slip as well

 

[mike wightman]

Going back to the ships I quoted above as mixing things, there's a more likely explanation and that is that the Gazelle and the Kinunir were designed using High Guard first edition - although they would have to be fudged from that since the PAW turret is implied but not actually listed

There is another source of mixed designs and that is the Games Workshop licenced product IISS Ship Files - it even gives LBB2 rules for energy weapons and nuclear dampers.

As far as mixing the ship paradigm goes Supplement 7 Traders and Gunboats shows that LBB2 first edition designs exist in the same universe as High Guard second edition designs - which is another problem entirely - and yet LBB2 second edition can't replicate the design of the X boat.

 

[far-trader]

Originally posted by Sigg Oddra:
As far as mixing the ship paradigm goes Supplement 7 Traders and Gunboats shows that LBB2 first edition designs exist in the same universe as High Guard second edition designs - which is another problem entirely - and yet LBB2 second edition can't replicate the design of the X boat.

Same thing in Supplement 9 too

 

[mike wightman]

Yep, and by Supplement 9 the OTU has completed the switch to large ships and High Guard TL progression - except of course for the TL9 Scout being jump 2, and the TL10 X boat being jump 4.

I don't know why they didn't redesign them using High Guard?

A TL13 X boat is easy, and the scout can be built at TL11.

 

[mike wightman]

Oh, and Dan, I haven't forgotten about that TL21 jump equipped battledress idea either

 

[Tobias]

Originally posted by Sigg Oddra:
The 800t merc cruiser is a force to be rekoned with in a universe where 400t SDBs defend systems and the top of the line Imperial battle cruiser is the Kinunir, four of which are all that is needed to defend the Spimward Marches

A universe where an 800 ton Merc Cruiser is a force to be reckoned with requires and extensive modification of the economic base points of Traveller. Either Starship prices need to be modified by a factor of, say, about 100 or population levels do.
If you don't, an 800-ton ship is insignificant.
As for the Kinunir as major fleet units: This whole perception is based on a rumor by a civilian. Knowing the kind of bullshit rumors that real-life civilians tend to spread about military hardware...

You mean like tha major rewrite of High Guard first edition to produce sedond edition, or more like the major rewrite that produced second edition, or revised, CT in 1981 and then The Traveller Book and later Starter Traveller?

No, I mean a major rewrite like MT. The CT editions can be called re-edited at best.

The Gazelle as originally presented in JTAS was armoured and equipped with PAWs, and the Kinunir, with its black globe and PAWs.

Yep, and both were originally somewhat different from their final, "official" HG selves. The earlier versions were likely produced using a WIP version of HG (or HG1?).

Yep, as the OTU was detailed it moved further from the original small ship universe - although TNE almost brought it back

TNE? Small ship universe? Not one bit! Do you own Battle Rider? Have you looked at the starship encounters table in TNE?
The first TNE product I ever bought was Brilliant Lances, and after looking at that I, too, thought, they were aiming for a small ship universe. BR and the TNE rulebook soon proved me wrong.

Regards,

Tobias