Ship Design Philosophies

[SpyderGS]

I've been tinkering with ship design and I am somewhat puzzled by the general design philosophy in the overall Traveller universe.
Correct me if I am wrong, but here we pick a pre-sized and generically shaped hull and try to cram as many goodies into it as we can.
In reality (yes I know it's a bloody game, but bear with me), we pick out all the goodies we need to make this craft what we need and then fit a hull around it. So if all you stuff comes out to 2231 tons that's your ship. I realize that some things are based on hull tonnage, but for the most part they won't affect the size categories, and if they do, a quick recalc using the next model up generally corrects that.

I'd like to hear other people's takes on this.

Thanks!

 

[tjoneslo]

In High guard, most of the important components (MDrive, JDrive, Power Plant, fuel for the above, armor) are all a percentage of the hull. That leaves weapons, crew, and cargo as non-percent-of-hull-based components. And the number of weapons you can mount is a % of hull size, such that a 101 ton hull can't mount any more weapons than a 100 ton hull. And the crew requirments are based upon the size of the drives and number of weapons.

So, since a majority of the components that fit into a starship hull are based fully or partly upon the size of the hull, using nice round numbers for the hull size makes the math easy.

The components first approach you advocate isn't wrong, it's just that the HG and T20 starship design systems have been optimized for structure first design. That is, changing the size of your hull requires recalculating the values of 75% of the components with in the hull. So why bother doing the work when you don't have to, besides every ship needs a little cargo space.

 

[Falkayn]

Originally posted by Spyder:
I'd like to hear other people's takes on this.

Well, I designed a 40.5 ton fighter the other day because I couldn't quite get everything I wanted into 40 tons ... if you're using a ship design spreadsheet/program that bases itself on the underlying formulas then you can pretty much take a hull as a starting point, do everything else and then finesse the actual hull size larger/smaller and see what you can end up with.

Let me know if you'd like to look at my T20 Starship Design spreadsheet.

 

[BrennanHawkwood]

I'd also consider the in-game vs. out-of-game angle. Just because we design ships starting with a hull and working in because it is the most convenient way of doing it with the game's design system, doesn't mean that things are done that way in-character. There is no reason that you can't indicate that the designers started with certain components as the base requirements and worked out when you write up the flavor text describing the ship.

 

[BigBadRon]

Trillion Credit Squadron games usually specify requirements for drives, fuel tankage, etc, for the ships. The hulls then have to be selected to suit those components and the other bits and pieces that have to go in.

In game I think it's fair to assume that the designers start with the interior components and fit the hull around them. The hull-first method is simply a game-device to make designing ships easier.
The only exception might be with the "standard hulls", as in the case of the type "S" scout and type "J" seeker which are based on the same hull. If the hull is already available (and it's cheap) then it might be easier for the architect to select components that fit within that hull.

 

[Bishop Odo]

There is one rule that helps a little that 20% fudge factor, so that 40.5 ton fighter is ok. I have been thinking that because of all the errors in the T20 and the other systems ship stats, such as the T20 omission of airlocks and cargo doors, to boost the fudge factor in MTU to 40%, or even going to the ½ jump fuel option rule, I have also, been entertaining the creation of my own system, a tweaking of the current T20 and MT, that would allow more performance variation with out jeopardizing safety, and adding racial specialties to ship designs.

After all, with all the errors out in circulation, is having to redo a few ships, that much of a bother and most of the time you can let it slide, after all this is a role-playing game not a truly completive board game.

 

[tete]

i think the size first makes sense. If you were
working for a car company they would tell you they want a new mid-size car (or whatever) then the engineers would have to try to make all the wanted features fit and they may have to fudge or scrap some of them basied on cost or size. Just the way i look at it

 

[Tom Schoene]

FWIW, my general approach to ship design is to write two lists. One consists of all the percentage-based components (drives, fuel, armor, etc.) The other consists of all the fixed systems (screens, spinal weapons, and associated power plants). From these two, I can do a rough cut estimate of the overall size of the ship. I'll usually round up a bit to include any elements that were overlooked, and to give some general cargo space (even warhips need room for spares and supplies).

For example, if my ship has 65% of its volume accounted for in percentage based compnents and has 1000 tons in fixed components, I know the total displacement will be around 2860 tons. I would round up to 2900, or even to 3000 to leave a little growth margin.

 

[GypsyComet]

The 20% fudge factor is for going from stats to deckplans, not for fiddling the design numbers themselves...

 

[Spyder_GS]

Well, I had been working on a number of spreadsheets to do this work, BUT Falkayn has kindly sent me a copy of his which is nothing less than fantastic! It does everything I've been looking for and it works just fine for the components first approach...I simply fill out the desired components first, get a quick overage from the totals line and then slap in a hull with a slightly infalted number to permit installation of the percentage base items. I can then continue to play with the hull size until I get the fit I want.

There are plenty of instances where there will be preset hull sizes, I will not deny that, but major shipbuilders construct one-offs and additional ships built of that type make it a standard hull size.

Most likely I will use a mix of the two philosophies. Thanks for all the feedback!

 

[christopher.boote]

Historically, the reasons for an 'outside-in' approach were twofold.
i) The Larry Niven / Known Space paradign, of a series of fixed size, mass produced hulls held over from CT, into MT and then onwards.
ii) (as discussed above) the size of Fuel Tanks and Bridge (ONLY! in CT) were %age based - so it made it trickier to design inside-out. But not impossible - all the drives and whatnot are fixed sizes in CT.
Theoretically this makes designing ship plans for CT ships easier - you just design a Type A J drive, then a type B, C etc until you have fixed deckplans for every drive type. However, noone else seems to do it that way

 

[Falkayn]

Originally posted by Spyder:
Well, I had been working on a number of spreadsheets to do this work, BUT Falkayn has kindly sent me a copy of his which is nothing less than fantastic! It does everything I've been looking for and it works just fine for the components first approach...I simply fill out the desired components first, get a quick overage from the totals line and then slap in a hull with a slightly infalted number to permit installation of the percentage base items. I can then continue to play with the hull size until I get the fit I want.

For those interested in that spreadsheet, it can be found on my Traveller Downloads page.

 

[Tom Schoene]

Falkayn:

Very handy. I've been playing with this for a few days and found a couple of things that probably need fixing

1) Meson Screen power use. The number in the table needs to be multimplied by (0.01 * displacement) to get the total power requirement. This is an easy fix.

2) There's no way to specify larger batteries of turret weapons. That mneans the gunners required nmumber is usually too high. This one isn't so easy a fix.

3) I believe that the first airlock is included in the bridge displacement, so it should not eat up 3 tons worth of otherwise usable space. This is of course a topic of some debate.

 

[Falkayn]

Originally posted by Tom Schoene:
Falkayn:

Very handy. I've been playing with this for a few days and found a couple of things that probably need fixing

1) Meson Screen power use. The number in the table needs to be multimplied by (0.01 * displacement) to get the total power requirement. This is an easy fix.

2) There's no way to specify larger batteries of turret weapons. That mneans the gunners required nmumber is usually too high. This one isn't so easy a fix.

3) I believe that the first airlock is included in the bridge displacement, so it should not eat up 3 tons worth of otherwise usable space. This is of course a topic of some debate.

Tom, thanks for the feedback!

1) Good spot, I'd seen that once before, but forgot to add it into the calcs, I'll update the spreadsheet.

2) You're right, there is no easy way to do this, particularly if you want to mix battery sizes. I decided to KISS it and have the recommended crew size specify the max number of gunners - feel free to put less (or more). That whole crew area works a bit like that...

3) I can see the point, but for the moment I am erring on the side of it being extra. If I'm wrong then my ship designs can all spend an extra 3 tons on something else!

Cheers,

 

[jfwking]

A very handy item indeed, many thanks for making it available.

A slight problem at the bottom, when buying ships stores the cost is in credits but is in the Mcr column which pushes the price up a bit as it is added as Mcr onto the ship price. 35 high passangers cost more than the 800 ton ship I was designing

Also a question. How do you get ships troops on smaller ships, they only seem to show on capital ships ?

 

[sea_tyger]

Originally posted by Captain Jonah:
A very handy item indeed, many thanks for making it available.

A slight problem at the bottom, when buying ships stores the cost is in credits but is in the Mcr column which pushes the price up a bit as it is added as Mcr onto the ship price. 35 high passangers cost more than the 800 ton ship I was designing

Wow, you're right...that's some expensive air. Excellent program, otherwise!

 

[Falkayn]

Originally posted by Captain Jonah:
A very handy item indeed, many thanks for making it available.

A slight problem at the bottom, when buying ships stores the cost is in credits but is in the Mcr column which pushes the price up a bit as it is added as Mcr onto the ship price. 35 high passangers cost more than the 800 ton ship I was designing

Also a question. How do you get ships troops on smaller ships, they only seem to show on capital ships ?

Your welcome!

That bug has been fixed in the next version already. I will get something out in the next couple of weeks.

The THB doesn't mention the idea of ship's troops so I left it off the recommended crew list. That area is only loosely coupled with the actual number of staterooms, so I didn't get creatve with it. But, now that I have a nicely laid out printout that reports those details I can see that some additions might be useful, such as:
- Ship's Troops
- High Passengers
- Middle Passengers
- Low Passengers

These last 3 might get their own area so as to not be reported in the total "Crew" number.

 

[tenntrav]

I downloaded your most escellent spreadsheet. There seems to be a bug in the Missle Bay weapons area. USP for 100 ton is 8 and for 50 ton is 9. Similar issues with the nukes.

Also, the note on Spinal mounts says valid values are 0-1 when it should be 0-2 (2=Meson).

The divide by 1MCr was mentioned earlier, so I'll leave that.

TTFN

tenntrav

 

[tenntrav]

Also, check out the service and ship's troops functions in the capital crew. For a 17,500dT cruiser, I'm getting 105 ship's troops and 36 service crew. It might be the other way around, but 105 troops is too high.

tenntrav

 

[CarlP]

I also wanted to add my kudos for the spreadsheet. I've got some old designs from CT that I've been trying to convert over to the new system, and this spreadsheet is going to make the project manageable. Thanks! I look forward to the corrected version.

Carl