"Correct" Book 2 Drive Tables

[daryen]

One of the major things that have always bothered me about the Book 2 Drive tables (including jump, manuever, and power plant) is that the chart gets horrible skewed once the ship hulls pass 800 dtons. At that point, they start pulling things in on the drive performance table so that the bigger ships get much better performance in order to allow J6/M6 performance with the imposed limitations of the 24 drive letters available. This makes the bigger ships much better than they should be. However, this is fairly easy to fix with the application of maths.

To figure this out, I replaced all of the drive letters with sequential numbers of 1-24 instead of A-Z (minus I and O). Then I extended the table to go as high as needed to let the implied formulas fit hulls all the way up to 5000 dtons. Doing this reveals that the 5000 dton hull requires a drive number of 150 to get a performance of 6. The other thing one notices is that we don't really need all 150 drive numbers. We only need about 30 or so of them. But, if we then combine numbers a bit (like putting 20 and 21 together and 120 and 125 together), we can barely squeeze everything back into the 24 slots the drive letters provide us.

The result is a table that is the same through drive letter F, but then starts increasingly ramping up from there. Letters G-J increase by 2, K-M increase by 3, N-S increase by 5, and the last seven increase by 10, 15, 20, and the last one by 25 to let us get to the drive number 150. This results in a drive number that looks like this:

The non-bold letter in parentheses are the original drive letters. So, for example, the new drive letter M is the same as the original drive letter W.

For the performance, we get:

Fuel requirements do not change, but, again, I strongly recommend using the 0.01*hull*Power to calculate the Power Plant fuel so that, again, things aren't so heavily skewed towards large ships. That is in no way necessary, as the official fuel requirements work well enough. Do note that all standard ships over 200 dtons will have to be recalculated for these updated drives because all drive letters G and above mean something different now. However, they shouldn't change in performance; it will just be a different drive letter. Any ships 1000 dtons and larger will have performance changed, however, which is the whole point of this exercise.

I know no one will ever use these tables, but I had fun putting them together. It was a fun challenge to keep the 24 letter limitation, but still make things fully work through 5000 dton hulls. Enjoy!

BTW, I took these tables from Cepheus. Cepheus uses the exact same tables and formulas as Book 2 (*), but adds in some extra hull sizes. Rather than delete the extra hull sizes, I decided to just leave them in. The above tables still apply to Book 2 exactly.

(*) There is one exception. Maneuver drive A has a size of 1 dton in Book 2, but 2 dton in Cepheus (as a one-time break of that formula). I made things match Book 2 in these charts.

 

[aramis]

You're not the first to do similar, both the extraction of the implied formulae and producing a variant table.
I, myself, did similar in the late 80's (when learned how to use Appleworks spreadsheet on the Apple II).
Then I gave up and went MT....

That said, Nicely done! Well justified and presented.

But one thing is missing (and it's not readily apparent in CT Bk2): tech level for various sizes? Standard CT or not?

 

[daryen]

I would just continue to use the TL table given in TTB/Book 3. It lets better performance happen earlier on larger hulls, but that's the penalty for redefining what the letter codes mean. Honestly, I could be talked into just limiting jump using the traditional TL chart, and not limiting any of the drives by TL. In other words, you can make a drive Z at TL 9, but that still isn't going to give you jump 6 until TL 15. Before then you're just wasting space and money. (Or do both: keep the TL table from TTB/Book 3, but in addition limit jump to the traditional TL chart.)

I know I couldn't possibly be the first to do it. It is just too obvious. Plus, I am not 100% sure that my approach is actually correct. Even so, it does what I wanted it to do, which is quit giving huge advantages to larger hulls when all players get is tiny hulls.

Also, I made a mistake in the Drive Performance table at the ends of the 1400 and 1600 hull size lines. Corrected chart is here:


In addition, I explicitly note the three entries I fudged in dark red. In all three cases, they barely missed the target number (by one), but I let it slide. To be more strict, just reduce the number by one and, in the case of 1200 ton hulls, add a 6 for the R drive. (Yes, this means that the way I compressed the drive sizes, without the fudge, a 500 ton hull jumps from J4 to J6 in the chart. I'd leave that one alone, at the least.)

 

[daryen]

As a follow-up thought, the other efforts I had seen before (including what was done in MgT HG 1e) was to extend the tables past Drive Z. I didn't want to do things that way. I wanted to re-scale the drives as needed to fit into the A-Z system. That way it still stays simple and it is easy to use, but it fully covers ship sizes from 100 to 5000 tons. There were a couple comprises in it, but overall I was pleasantly surprised at how well it worked out.

P.S. Just noticed that the title should have said "Corrected", not "Correct". And, yes, the title was intentionally presumptuous.

 

[Grav_Moped]

The interesting bit about the drive tables (to me, anyhow) is that before the TL-15 drives W-Z, there is only one exception to the underlying formulae: the size J drive in a 2000Td hull has its performance rounded up (it should have a rating of 0.9 and thus a dash in the table, but instead has a rating of 1). I'd half-expected glitches at the Size J and Size P drives as a copyright trap, but they didn't go there.

 

[kilemall]

Verah nice!

 

[daryen]

Example ship changes ...

The Traveller Book:
Type A, Type S, Type R, Type Y, Type L, and Type K are all unchanged.
Type T: change maneuver-H and power-H to maneuver-G and power-G. Just a label change.
Type C: change drive-Ms to drive-Js. Just a label change.
Type M: change jump-J and power-J to jump-H and power-H. This reduces cargo by 8 to 121. (The original drive-J was skipped, so it "overdrives" to the next step at the cost of the space removed from cargo.)

CotI:
Type J and Type P are unchanged.

The Traveller Adventure:
Type VA and Type VJ are unchanged.
Type VP: change maneuver-K and power-K to maneuver-H and power-H. Just a label change.
Type RT: change jump-V, maneuver-E, power-V to jump-M, maneuver-E, power-M. Reduce cargo by 8 to 122.
Type AT: change jump-Z, maneuver-Q, power-Z to jump-U, maneuver-K, power-U. Reduce cargo by 288 to 971.
Type TI: change drives-W to drives-M. Just a label change.
Type TJ: change drives-Z to drives-U. Reduce cargo by 360 to -166 (i.e. it doesn't fit).
Type AH: change drives-W to drives-N. Reduce cargo by 40 to 4029.
Type CT: change jump-Q, maneuver-E, power-Q to jump-K, maneuver-E, power-K. Just a label change.

As you can see, the more performance on the bigger hull causes the bigger change. Which is the entire point of the changes being made. This really comes to roost for the TJ. Which, again, is the point. The TJ was explicitly built on the compression at the high end of drive chart, effectively exploiting a loophole. With the "corrected" tables, the TJ is screwed.

To make the TJ work is hard. You'd need to drop the maneuver drive to M, giving 2G performance, force double occupancy (while allowing for the significantly increased engineering crew) to save a few staterooms, and use the "proper" Book 2 PP fuel requirements (itself its own loophole), and you *almost* make it work. There is no cargo outside the shuttle, however. Also getting rid of the shuttle makes the math work and gives a really small cargo hold.

So, with that small sample size, the "correct" tables seem to do what is intended, yet every single design still works (even the massive AH), with one exception. And that exception is the one design that was literally built around the incongruities of the original tables.

 

[infojunky]

Well now, I am pondering ship construction again. Currently I am staring at Book5 and contemplating the The K'Kree shipbuilding rules from that alien module to fit Book5 ships into Book2 style combat.

Though the small ship universe of book2 Appeals to me quite a bit. I have run out tables like MgT for 25 standard drives with 5000 dTons limited to the performance of one, though the concept of multiple drives does amuse me as well.