Traveller Q&A: Official Answers To Your Questions

Last Updated 3 February 2000.

Digest 11

[This page is a copy of "Traveller Q&A", Travellers' Digest issue 11, Digest Group Publications, Boise, ID, USA, 1988, pp 38-39.]

Traveller Q&A provides answers to questions from readers on various aspects of Traveller, MegaTraveller, and 2300. If you have a question you would like to have answered, send it to: Digest Group Publications, Q&A, 8979 Mandan Ct., Boise, ID 83709. We will publish the best of these questions and answers in this column. (Editor's Note: We especially need 2300 questions. if you have any questions on 2300, by all means, send them in.)

Every single answer published in this column is seen and approved by Marc W. Miller, the leading designer of Traveller and 2300. We want to stress to our readers that anything appearing in Traveller Q&A is official unless explicitly stated to be a variant.

Why is the 'ton' used to measure both displacement (volume) and physical weight? For example, the G-Carrier discussed in Grand Census displaces less than 9 'tons', yet weighs 72 'tons' when empty. Is starship performance affected by cargos of excessive weights, even though they fit in the ship? - J. N.

MegaTraveller craft design clarifies the definition of the various types of tons on page 57 of the Referee's Manual.I agree with you that the terms can be confusing - which is why I tried to get away from using "tons" for volume, and using kiloliters instead for vehicle and spacecraft design. Our preference here at DGP is to clearly specify when we are talking about a displacement ton. For example: a Scout/Courier has a size of 100 displacement tons. To recap, here's the definitions given in MegaTraveller:

Tons Displacement: A widespread method of specifying a space vessel's size is to give its volume in terms of the amount of liquid hydrogen it would displace (as if it were immersed in a vast sea of liquid hydrogen). Tons displacement is not to be confused with the craft's weight in metric tons (that is, its actual mass). A starship that displaces 100 tons may actually weigh over 1,000 metric tons. A displacement ton is a measure of volume rather than weight; one displacement ton equals 13.5 kiloliters of volume.

Volume:A craft's volume is the amount of space it takes up. Volume is measured in kiloliters - a kiloliter equals one cubic meter. Thus a cube that is one meter on a side has a volume of one kiloliter. A kiloliter contains 1,000 liters; 13.5 kiloliters equals one ton of displacement.

Weight:A craft's weight is measured in metric tons. One metric ton equals 1,000 kilograms.

To answer your question about excessive cargo weight affecting starship performance, in MegaTraveller, loaded weight is computed using the mass of a cargo hold totally filled with water (i.e., 1 metric ton per kiloliter). This, clearly, is more massive than a typical cargo load.

Clarifying the distinction between displacement and mass has several interesting effects on the MegaTraveller craft design system. MegaTraveller ship performance (agility) is based on true ship mass, not displacement, so ship performance is realistically affected by changes in the ship's mass. I think this makes starship design in MegaTraveller both more fun and more challenging.

For example, if you want to armor your ship's hull to the hilt, you'll pay the price. Your ship's mass is going to sky-rocket, and your ship's agility will suffer. The ship's displacement remains unaffected. -Joe D. Fugate Sr.

Can energy accumulated in the jump drive capacitors from a black globe generator in combat be used exclusively to power a jump, or must jump fuel be used in any case? - J. K.

As stated in both High Guard and the MegaTraveller Referee's Manual, a starship's jump drive capacitors can be used to divert or "bleed off" the energy absorbed by a black globe when the screen is hit in combat. The rules, however, are unclear on this point, largely because of the word "capacitor". Because the jump drive capacitors are being used, many have just assumed the energy could be used to charge the hull jump net, and thus send the ship into jump. Unfortunately, that does not work. The jump drive must still be used to charge the capacitors and power the jump.

The energy from the black globe is of a low grade, while the energy generated by the jump drive is of a much higher grade. The jump drive capacitors are able to absorb the black globe energy, but they cannot use it to effectively power the jump net in the ship's hull. The low grade energy allowed to leave the ship after the black globe is off exits the ship via the jump drive hull net as ordinary heat energy. It is useless for propelling the ship into jumpspace. (Incidentally, note why the black globe generator has to be off to allow the heat energy to leave. Were the energy allowed to leave while the globe was on, the heat build-up inside the black globe sphere would melt the ship's hull.)

The statement in the rules that says "If the ship absorbs enough energy to make a jump, and is supplied with sufficient fuel, it may jump" is misleading. The jump drive must still be used as normal to enter jumpspace. Whether or not a ship has a black globe really has nothing to do with going in-to jump. - Marc W Miller.

If you have bay weapons of a particular type, does that preclude turret weapons of that type? Do hardpoints cost or weigh anything? - J. K.

In original Traveller, you could not mix bay and turret weapons on the same ship. With the new MegaTraveller rules, you can. The new Universal Craft Profile is much more flexible in that regard.

Hardpoints do not cost anything per se. A hardpoint is a design designation when the craft is on the drawing board. The mounting hardware and the "weapon" itself that go into the hardpoint are where the cost and weight come in. - Joe D. Fugate Sr.

How do robot brains differ from starship computers? - J. K.

Robot brains tend to be more specialized and less deterministic (i.e., more synaptic). Robot brains are also optimized for size, since they must often fit in a very tiny space.

Starship computers must monitor, self-test, diagnose, and control literally millions of complex components. Because of this, the more predictable (and cheaper) deterministic computers are used. Some synaptic processing exists in starship computers at the higher tech levels (13+), but the synaptic results are always cross-checked by the deterministic portion. - Joe D. Fugate Sr.

It appears that the quantity of jump fuel needed for jumps higher than jump-1 has decreased in MegaTraveller. At jump-6 only 35% of the ship is needed for jump fuel, as opposed to 60% of the ship in the old system. Was this intentional? - R. D.

Yes, this was quite intentional. in making Striker fuel consumption fit with starship fuel consumption in the new system, it became apparent that a Striker fusion power plant consumed a lot more fuel than was indicated in the starship design systems for a power plant So to compensate, jump drive fuel requirements were reduced. However, the result is that the volume that must be devoted to fuel tankage as a whole was only slightly greater on the average. The net effect is that little change in total fuel requirements has been made. Here are some comparisons of ship fuel requirements:

Disp Mn Jn Old
Scout 100 2 2 40 tons 38 tons -2%
Seeker 100 2 2 30 tons 37 tons +7%
Free Trader 200 1 1 30 tons 46 tons +8%
Far Trader 200 1 2 30 tons 50 tons +10%
Fat Trader 400 1 1 50 tons 79 tons +7%
Yacht 200 1 1 50 tons 40 tons -5%
Patrol 440 4 3 160 tons 187 tons +6%
Merc Cruiser 800 3 3 318 tons 303 tons -2%
Lab Ship 400 1 2 90 tons 85 tons -1%
Safari Ship 200 1 2 60 tons 57 tons -2%
Close Esc 330 5 5 181 tons 185 tons +1%
Average: +3%

Notes: M = Maneuver, J = Jump. Variance is expressed as a percentage of total ship displacement, old to new. - Joe D. Fugate Sr.

According to my calculations, the Starships in the MegaTraveller Imperial Encyclopedia were all designed with a basic life-support volume and weight figure of 0.005. This is contrary to the figure of 0.050 as shown on the Environmental Controls table on page 81 of the Referee's Manual. Is this so? - J. F.

You are right! Good catch: that one slipped by us. The correct volume and weight figure for basic life-support is the 0.005 figure. Thanks for pointing this out. We'll make sure this gets added to the latest edition of the MegaTraveller errata, available by SASE from GDW. - Joe D. Fugate Sr.

Return to Tavonni Repair Bays
Return to Top of Page