Drive Volume %s

[pasuuli]

Looking at the core rules, I see that CT Book 2 is followed -- for the first few drives, anyway, then the curve gets gentler to get more mileage out of the drive letters.

I like the larger relative drive sizes in the core rules, but the progression doesn't seem to follow a formula. Of course, this doesn't really matter -- until we get to High Guard.

Then looking at High Guard, I see that there are formula for calculating drives, but they're even more different than the core rules. Or maybe they're not, but I can't see the relationship.

Okay, so I like the formula to be there. But, I also like the drive sizes from the core book.

Doesn't it seem reasonable to have one set of formula to rule them all?

 

[sideranautae]

Doesn't it seem reasonable to have one set of formula to rule them all?

Yes, I think it wold be a better idea.

 

[Jeraa]

Doesn't it seem reasonable to have one set of formula to rule them all?

It would be reasonable to have one, unified ship design sequence. Instead we have 3 (small craft, 100-2000 ton ships, and 2000+ ton ships).

There is no (good) reason to have 3 separate design sequences for what is basically the same thing. One design sequence, with minor changes to fit the different size of ship, is all that is really needed.

 

[Reynard]

Other editions have created a unified design system that even incorporate vehicles and robots. I have to assume Mongoose licensed the use of Classic Traveller systems with some variation and additions. I believe the inconsistencies with Core and High Guard began there and ported over.

The MgT Core K.I.S.S.ed the ship design rules while High Guard should have allowed an extended, detailed system for all ship designs as the original did. I don't have the Original High Guard nearby but wasn't the ship profiles and combat system also different than the Core rather than just additional rules?

 

[dragoner]

Doesn't it seem reasonable to have one set of formula to rule them all?

Whatever is simplest and gets the job done for the game is best. Reality, you would go by thrust vs mass, which is not the way Traveller does it anyways.

 

[sideranautae]

Reality, you would go by thrust vs mass, which is not the way Traveller does it anyways.

If MgT used reaction mass drives that would be the case. MgT uses gravitic drives which could just as well effect all mass in given volume equally. A la gravity imparting the same acceleration on a feather (1 gr.) or lead weight (100 kg.) in the same grav well...

 

[pasuuli]

Maybe worse than having 3 different design systems would be breaking compatibility. Suppose a unified system broke capital ships? That would be bad. And if it broke small ships, that might even be worse. I hate that. It seems to be a no-win.

So looking at small ship design, it seems to be directly related to the core book ship design system, doesn't it? So in a way it isn't all that different, except in scale.

 

[sideranautae]

So looking at small ship design, it seems to be directly related to the core book ship design system, doesn't it? So in a way it isn't all that different, except in scale.

It is different in scale and other rules. Relating to weapons carried and the like. Also, it is difficult to design some of the higher G M-drive small craft. Also, some of the computer automation rules for TL's in the 11-15 range are actually below what exists at TL 7. So, some errata needed there as well

 

[Infojunky]

I like the larger relative drive sizes in the core rules, but the progression doesn't seem to follow a formula.

There is a formula for all three drives:
Maneuver = (H x M / 200) x 2 - 1
Power Plant = (H x P / 200) x 3 + 1
Jump = (H x J / 200) x 5 + 5

Where H = Hull tonnage. And the other variable is the drive rating.

Mind you there are some Rounding outliers when translating these number to a chart.

 

[pasuuli]

I like the larger relative drive sizes in the core rules, but the progression doesn't seem to follow a formula.

There is a formula for all three drives:
Maneuver = (H x M / 200) x 2 - 1
Power Plant = (H x P / 200) x 3 + 1
Jump = (H x J / 200) x 5 + 5

Where H = Hull tonnage. And the other variable is the drive rating.

Mind you there are some Rounding outliers when translating these number to a chart.

That formula works very well, until I get to the 800 ton hull. Then things seem to go wrong. Or maybe I'm doing something wrong? By the way, I'm using the very handy Spacecraft Design Sheets from Moon Toad, which is just the ship design tables from the core book and HG together... maybe there are some typos in here?

Since I only have Moon Toad with me, and not the core book, I can't look this up, but can someone tell me if Jump-4 in a 1000t hull actually displaces 105 tons? In this supplement it only displaces 75 tons... which just seems wrong.

If so, and the formula actually applies to the entries in the core book, then perhaps Moon Toad has errata to deal with.

 

[Reynard]

A 1000t ship with J4 in the Core book is 75t. That formula above makes it 105t. Big difference.

 

[Infojunky]

Since I only have Moon Toad with me, and not the core book, I can't look this up, but can someone tell me if Jump-4 in a 1000t hull actually displaces 105 tons? In this supplement it only displaces 75 tons... which just seems wrong.

Drives P, Q, R, by the TMB revised. 75, 80, 85.

Ok, a note of clarification, the numbers I pulled where from the T5 draft, which I have from a number of sources is the same draft that was ceded to Mongoose for the draft of their edition of Traveller. With that i haven't used any of Moon Toad's products nor given much of the capital ship construction rules from Mongoose's version of High Guard a look. (Personal Note, re High Guard/Capital ships, I generally run a small ship universe game in which most ships are under 5000 dtons, and the ships that exceed that are universally commercial hulls. Said ships generally exists a rough mock ups to find out costs and load volumes under CT's High Guard, as they were created to flesh out economic trade volumes for intra-system ship traffic volumes. As such the few times I have had need of the big liners i use those numbers.)

 

[Infojunky]

A 1000t ship with J4 in the Core book is 75t. That formula above makes it 105t. Big difference.

Your absolutly right and took numbers from T5 and not my notes.... (Crap where is my cheat sheet!?!?!)

 

[sideranautae]

A 1000t ship with J4 in the Core book is 75t. That formula above makes it 105t. Big difference.

Your absolutly right and took numbers from T5 and not my notes.... (Crap where is my cheat sheet!?!?!)

If you find that formula for MgT DO please let us know. Could come in handy.

 

[Infojunky]

Ok this is a little embarrassing, when i was figuring out the letter drives i was working off of old CT notes and other editions of Traveller, and as such the equations I quoted work for those editions and only kinda work for Mongoose. As the potential table in the TMB as a hook in it significantly lowering the amount of drive needed for the larger adventure class hulls.

As of right now I don't have a easy equation for the Standard Drives for MgT.

 

[pasuuli]

As of right now I don't have a easy equation for the Standard Drives for MgT.

It seems that drives become more powerful when used in larger hulls. If this increase in power is directly related to the hull volume in a consistent manner, then perhaps we do have a formula in there somewhere.

Now, if we take those drives as being "atomic" or "axiomatic" then maybe a generalisation could be made at the upper levels, by which formula could be derived for larger drives. And at the lower levels, the original equation is preserved, and so maybe it could apply to small hulls, to some degree (maybe that application is what Mongoose did for small hull drives in the first place).

 

[pasuuli]

Findings So Far

There are two zones that guide drive strength: from 100 thru 600 tons, and 700+ tons.

First Zone. The first zone, encompassing hulls from 100 thru 600 tons, is completely regular and identical to the CT Book 2 drive potential table.

Second Zone. The second zone re-jiggers the drive strengths so that the drive potential progresses at the "600-ton" level, at a rate of one point per 200 tons. Thus the relationship is that of an offset from a 600 ton hull, something like this:

Jump Rating = [Drive "Power" / 600] - [Hull volume - 600]/600
Jn = [Power - Hull]/600 + 1

Assume that "Drive Power" is in increments of 200: A=200, B=400, C=600, K=2000, V=4000, and so on.

For example, a 1200t hull with an "S" drive (power=3400):

[3400 - 1200]/600 +1 = 2200/600 + 1 = 4.6 = 4.

Drive Volume. Drive Volume from "Power" is

Drive Vol (tons) = Power/40 + 5.

So

Jn = [Power - Hull]/600 +1
Power = 600 x (Jn - 1) + Hull
Power/40 = (600 x (Jn-1) + Hull) / 40
Drive Vol = 5 + (600 x (Jn-1) + Hull) / 40
= 5 + (600 x (Jn-1) / 40) + Hull/40
* = 5 + (15 x (Jn-1)) + Hull/40

* this turns out to be slightly incorrect, perhaps by a constant (10), perhaps not.

Testing that with an 800t hull at Jump 3:

J-Drive Vol = 5 + (15 x (2)) + 800/40
= 5 + 30 + 20
= 55 tons

Close - looks like I'm off by 10 tons. But it's close.

 

[sideranautae]

Findings So Far

Close - looks like I'm off by 10 tons. But it's close.

That's why I just went with a simple formula for all ships 100+ tons.

 

[GypsyComet]

The volume-performance efficiency of drives starts poor at the small end of starships and gradually improves up to 2000 dtons, then flattens. I have no problem attributing this to undefined overhead elements of the drives that don't change volume at the same rate as the working parts at first, but which eventually just get lost in the round-off and/or scale with the drives after a certain point.

The graphs are a bit bumpy since Mongoose uses only whole tons (which is particularly bad in the subcraft).

 

[Infojunky]

More that once I have been tempted to go back to CT's Book 5 for basic starship construction, then add back in the the bits and pieces that seem to work best. or even better go to that percentage system and rebuild "standard" drives that based on a idealised tonnage and then mix and match from there.