Starship Design Example

[atpollard]

I was reading the

MT Starship Design Example

and was suprised at the comments on the required fuel. Am I alone in finding it excessive to provide fuel to allow 30 days of continous operation of the spinal mount, bay weapons and turret weapons. Would any starship survive even 24 hours (144 turns) of continuous combat? Rather than gut the ship of Jump Drives and Maneuver Drives, just reduce the operational time of the energy weapons.

I was just interested in hearing other thoughts.

 

[jtgibson]

Sadly, one of the (debatable) shortcomings of the MegaTraveller system is that it assumes that all screens, guns, drives, and other devices are running "hot" at all times. This helps balance out the fact that ships which have powerful weapons and drives actually need to mount tons of fuel and power plant output to be able to use them, but is a major handwave in terms of realism.

In the case of an aircraft, the engines have to run at nearly full power at all times -- an idling aircraft engine uses almost as much fuel as an engine at full power. In the case of a ground vehicle, the engine runs at minimal power when idling. The idea of how much power a spaceship uses when idling is a matter of debate, but one would assume that most of the weapons and screens would be completely unpowered, or running at only a capacitance-level setting.

I've been considering this in order to write a house rule, but haven't gotten to finishing it.

 

[aramis]

One of the things where MT differed from CT is allowing multiple PP's on at once. So for pirates, starmercs, and Naval Ships, I often put only a week for the combat plant, and 28 days (an imperial month) for the Base Ops Plant.

Also, in MT, you can run a plant down to (IIRC) 30% with a parallel lowering of fuel used; thus 7 days in Jspace is gonna count 3 days fuel for a typical single plant ship.

 

[GypsyComet]

In fact, the "multiple short duration" powerplant epiphany, which happened more than three years into the MT era, was what finally made CT designs workable below TL15.

In design terms this doesn't change the size of the "powerplant" itself, since anything you're going to install on a starship will be above the top threshold for volume efficiency, but it impacts the fuel needs hugely. If you wanted to get really picky and somewhat risky, you could designate 30 days duration for the LS/controls/etc *only*, reduce drives to about 20 days, and weapons/screens to 1-2 days. Given that drives and weapons are generally 90% of your power needs, a 60-70% reduction in non-Jump fuel needs is certainly possible.

The additional color isn't a bad thing either. "We've got multiple intercept bogeys. Engineering, bring Reactors Three and Four online and rig for battle."

 

[DonM]

But unfortunately, the Example was written to design thought when MT was published, and I'd want to do a completely different ship for the "PP Epiphany". (I've never heard it called that before, but that is certainly what happened).

 

[Whipsnade]

... the "multiple short duration" powerplant epiphany...

GC,

I remember first reading about the epiphany in a DGP Q&A column.

My first reaction was "Phew, my house rule isn't too far off..."

My second reaction was "Why the #*&&#$@@ didn't they tell us this in the beginning?"


Have fun,
Bill

 

[DonM]

I first saw it in an online discussion on GEnie just before I resigned as a Quadrant Editor for HIWG.

 

[GypsyComet]

GC,

I remember first reading about the epiphany in a DGP Q&A column.

My first reaction was "Phew, my house rule isn't too far off..."

My second reaction was "Why the #*&&#$@@ didn't they tell us this in the beginning?"

Based on the DGP construction example referenced above, the DGP folks hadn't yet had the epiphany. In fact, it was one of the more prolific ship designers who apparently started it. The MOST prolific designer, Rob Dean, was just one step away from giving us the epiphany years earlier, as his solution for lower TL designs was to simply reduce the duration across the board. This was already a pretty radical step, by the way. It took another designer to hit on the final solution.

It was apparent that DGP recognized the problem early on, however, as the MT design system was where Jump fuel requirements changed. Looking at the whole picture, this step was obviously the attempted fix to the runaway powerplant fuel problem (which derived from using Striker assumptions for much larger vehicles than Striker was meant for). In retrospect, DGP should have introduced another step in fusion plant scale efficiency instead, but what's done is done.

Of course, the other problem is a "reality check" issue, and is what led the TNE revision to reduce all power numbers by an order of magnitude or more. The reality check comes from the simple triple beam laser turret, which is a modest one displacement ton structure that is being asked to channel 750 MW in one side, feed that much raw power into three laser emitters, and fire the resulting beams out the other side. All without melting the whole thing (or the conduits running from engineering to the turret) into slag (or boiling the metals off as vapor, for that matter). Repeatedly. 750 MW is a LOT of juice.

 

[zonk]

So what, exactly, does the PP epiphany require in the way of changes? I, vaguely, understand that multiple powerplants are required because of fuel limits.

 

[GypsyComet]

Here is the section summary from the MT Ship Design Example, trimmed to show just the power:

Hull Section Total 0
Locomotion Total -892,500.02
Communication Total -0.200
Sensors Total -1,011.70
Weapons Total -563,580
Screens Total -106,125
Environ Total -73,903.74
Fuel Purification -1,265.63

The total powerplant volume will be the same whether we make the default single plant assumption or a multiple plant assumption, because we still want, in this case, to be able to generate all that power at once. However, instead of using the total, let's break it up into sections. Spreading the 27,287 KL/day fuel requirement around proportionately, we get:

Hull Section Total 0
Locomotion Total 14865 Kl/day
Communication Total 0.033 Kl/day
Sensors Total 16.85 Kl/day
Weapons Total 9386 Kl/day
Screens Total 1767 Kl/day
Environ Total 1231 Kl/day
Fuel Purification 21 Kl/day

Now, instead of multiplying the total by 30, you pick and choose.

Hull, Commo, Sensors, Environ, and Fuel Purification are all on the full 30 day ride for 1269 x 30 = 38070 Kl of fuel

Locomotion for a warship is a complex issue, and one that calls for a closer look at the intended mission of the ship. For now, let's assume that 5 days at full juice will be enough. 14865 x 5 = 74325 Kl of fuel.

Finally, Weapons and Screens. If a naval battle lasts longer than a day or two, you're pretty much hosed anyway, so lets provide enough endurance to run these systems for two days. 11153 x 2 = 22306 Kl of fuel.

So these plus the total power plants volume of 181910 Kl, adds up to 316611, which is below the 323699 Kl that was available. Bump our maneuver powering fuel endurance up to 5.4 days adds 5946 Kl to the fuel for a total of 322557. We can simply add that last 1142 Kl (about 81 dtons) to fuel as a "last gasp" or to cargo as more ration carrying space. A bowling alley is also a possibility...

That help any?

 

[zonk]

I see but I'm not sure I understand.

You are just saying that you have fuel for the what you need. You make the decisions on how long each piece is going to run during the 30 period.

I'm OK with that.

So... what's the problem? A rule problem?

 

[DonM]

Let's try it this way...

Under the way the rules were written, the assumption was that you'd design a power plant in MT the same way you would with High Guard: one power plant for everything for 30 days.

When the PP epiphany came about, the notion was this: you'd have one powerplant for standard junk, putting around and stuff, but no weapons, screens, etc.

And you'd have a SECOND PP, which was designed to power EVERYTHING, but for only a 6 to 24 hour period (that was really never settled).

The cool part was that, much like the "Jane's" books, ships had "cruising stats" and "combat stats".

But the biggest impact was on FUEL TANKAGE. And designs suddenly started looking like their High Guard counterparts again.

 

[GypsyComet]

I see but I'm not sure I understand.

You are just saying that you have fuel for the what you need. You make the decisions on how long each piece is going to run during the 30 period.

I'm OK with that.

So... what's the problem? A rule problem?

The problem that created the need for this solution originates with the CT miniatures game Striker, which was the first appearance of the all-inclusive hardware design systems. Intended for ground actions, the technological assumptions of the design systems were centered on vehicles. Striker was very complex to set up for (home computer spreadsheets being a few years away yet), but worked for its chosen purpose.

A grey area was the section that addressed using Traveller starships on a Striker table. This section set the equivalents for Traveller weaponry and ship hulls in Striker terms. It was clunky, but it worked. For Striker.

Then Striker was used as the basis for the MT vehicle and ship design chapter. All the same assumptions were in use, but buried under a pre-designed component layer. This included the use of Striker numbers for starship-scale powerplants, and the Striker assumptions for ship weaponry. The combination made even the lowly Free Trader a virtual lighthouse of waste energy, with the turrets needing some truly frightening amounts of power, and the amount of (normally invisible) gravitic energy pushing the ship around was enough to cause a tail glow similar to a white hot rocket flame. The fuel to power this was immense, and far beyond what CT starship systems had assumed. Suddenly, CT designs couldn't be made to work, mostly because of the fuel needs to run the entire ship at full power for the traditional 30 days.

The barrier was one of subtle wording and tradition. A ship had *one* powerplant. Period.

Despite this tradition, there was also a long habit amongst ship deckplan designers to make the Engineering space look "right", so you would often see maneuver drives split into two or more units. That it took us so long to apply this conceptually to powerplants is a bit shaming, but even then the Traveller playing public was just barely starting to network on this new-fangled thing called the Internet.

(Yes, I realize it can be hard to conceive of now, but the Web didn't exist during the MT run, and even the unified Internet was barely underway when TNE took over from MT. Most of the MT era was the realm of direct-dial BBS systems with no interconnection, or of sporadically connected universities and government servers passing email and newsgroup information around. "Online" communications were still a non-trivial exercise, there were relatively few people to talk to, and bandwidth was a precious commodity.)

The conceptual leap of designing as if the "unified" powerplant was actually a cluster of dedicated plants, and assigning mission-determined fuel durations to each sub-plant, really came about because of the increasing communications between far-flung players. Without that, the published "There is but one Powerplant, and 30 days is its Duration" assumption would probably never have been challenged.

 

[zonk]

So was this the final group ... not decision, but general agreement? That the single powerplant was replaced by multiple powerplants, each with it's required fuel tankage? But since the other pp only ran during specific times the whole required less fuel?

I realize it's long passed but wouldn't it have been simpler to just figure the fuel on the parts that are being used? I mean that is effectively what was done, but required the second (or more?) pps? Not that that actually made any difference if I, vaguely, recall the construction sequence. Two pp would take the same space as a single twice as large?

 

[GypsyComet]

It was called an Epiphany for a reason. Many of the people using the design rules had been beating their heads against the "fuel problem" since MT came out.

Yes. Unless a particular "sub-plant" falls below one dton (14kl) displacement, the volume for the whole won't change.

The reason this method works better during design is that the calculations are straightforward. That is, they are the same calcs you are using anyway, but you are using them three or four times instead of once.

Coming up with some sort of Power-Time profile and fitting fuel usage under the multiple-order curve accomplishes the same thing, but with more math of a sort that, frankly, a lot of people have never been exposed to.

As noted before, just the concept of knocking *any* starship endurance below 30 days was a bit heretical. There were thus several conceptual barriers between the rulebook and the solution.

A side effect of this way of thinking is that a ship that doesn't use its hungrier systems already has its lower level fuel usage calculated, and can go for much longer than 30 days by using that fuel for the general systems plant.

 

[robject]

This is totally fascinating and completely new to me. Thanks for posting this!!

 

[jfetters]

Indeed! I vaguely remember the articles that have been discussed in the thread - I am going to have to dig through and see if I can find it.

I notice in TNE that Power plant fuel consumption is done on a per YEAR basis with regards to fusion. Is this one of the reasons behind that?

 

[DonM]

Be aware that there are other tweaks to the rules that are obvious if you change the way you look at them in the MT design system...

For example, when we first bought MT, the "jump units" and "maneuver units" tables totally confused us.

Imagine our embarassment about three months later when (I think) in a round robin mailing by Ed Edwards, Clay Bush pointed out that all those two extensive tables were was a fancy way of reprinting the "Drive Potential Table" from High Guard with absolutely NO changes.

IE- Jump Drive space is equal to (Jump # + 1) % of the ship, and Maneuver drive is equal to (Maneuver # x 3) -1 % of the ship.

A guy in our group liked using odd hull sizes, and had been "interpolating from the tables" madly using Lotus spreadsheets. Needless to say, he had some interesting words to say about the creators of the design system at that point.

Wish I still had those old spreadsheets.

 

[zonk]

A guy in our group liked using odd hull sizes, and had been "interpolating from the tables" madly using Lotus spreadsheets. Needless to say, he had some interesting words to say about the creators of the design system at that point.

Wish I still had those old spreadsheets.

Don, you're a cruel cruel man :rofl:

It's a fascinating story. I wish I had been interested in MT but I dropped out just before it came it.

 

[GypsyComet]

If my example is confusing to you (I know it is to me, somewhat) it's because I was trying to follow the same procedures that the DGP Design Example did. Some of those are bass-ackwards, though I can see some of the point in doing it that way, since the example does call attention to some factors hidden in odd corners of the design system. My own thought processes when using the MT design system are quite different...

Having been exposed to Striker, I was able to dive right in when the MT design system hit, and the big Design Example was much less useful as a result. What it did help with was a weak point in the design system presentation. A point helped only by the rather stilted collection of construction examples provided up to that point. Namely, "Which of these tables do I ignore if I'm building a starship vs a tank?"