Last night I began reading the rules for Mayday, GDW’s space combat game using the ships and themes from Traveller Book 2 as a hex-based board game. It looks fun! (The game is available in PDF form from DriveThruRPG for $9.99 and is included in the Classic Traveller CD-Rom/Thumbnail from Far Future Enterprises.)
A few things became clear reading the rules.
First, there is a reason Traveller’s starship movement is vector based and has templates for gravity wells around worlds. Marc Miller really likes vector based movement and gravity wells!
If you look at his game Triplanetary, you’ll see an entire game built around using vector based movement for racing and battling in space. The game came out 4 years before the original Traveller rules. Then, in the following years, Miller writes Traveller and uses the focus found in Triplanetary to create the movement and combat found in Book 2. Then, a year later, he takes the ships and details from Book 2 and basically uses the core concepts of Triplanetary to create a new board game as part of the Traveller line. Once you look at all three games at the same time you simply see the pattern!
(By the way, Steve Jackson Games is currently Kickstarting a new edition of Triplanetary. There are seven days left.)
But to more much practical details became clear when reading the Mayday rules.
For years I have been baffled by two elements of ship-to-ship combat in Traveller. First, how do missiles move? Second, how do the clouds of sand from the sandcasters move? The rules do not say (not in the 1977 edition, not in the 1981 edition, not in The Traveller Book, not in Starter Traveller). And these two components are really important to space combat!
But if you open up the rules to Mayday all becomes clear. In part because Mayday is a stripped down, simplified version of Traveller space combat. It is designed as a board game, not a miniature war game. And I believe Miller made sure that the language and explanations of the rulebook would be easy to understand for the more casual gamer.
I’m going to note these details here in case they are of help to you. (Many people have figured this stuff out by now. But I know these two points have remained a mystery and much discussed matter for decades.)
MISSILES
Missile movement is defined by its propulsion system. The propulsion system is defined by two numbers, commonly separated by a capital G. The first number is the maximum number of Gs which the missile is capable of in a turn; the second is the number of G-burns of fuel the missile can make at maximum G.
For example, a 1G1 propulsion system can accelerate a maximum of 1G per turn, and is capable of burning fuel to achieve 1G once. A 6G6 system can accelerate to a maximum of 6G per turn, and has enough fuel to reach 6G six times. A 3G3 system can accelerate to a maximum of 3G in one turn, and has fuel to allow reaching 3G for three turns.
Special Supplement 3: Missiles explains all this. But I have to say, reading it in Mayday finally made it click.
Of particular note: Both Mayday and Special Supplement 3: Missiles create templates for different kinds of missiles, with different sorts of propulsion, guidance, detonation systems and more.
As a general rule Special Supplement 3: Missiles states, “the standard missile in Traveller is a 5G6 continuous burn.” This mean that missiles in Traveller have a 5G thrust available per turn, that they can accelerate up to 5G six times before running out of fuel, and that they will keep moving toward their target as efficiently as possible until fuel runs out.
There are other factors one can apply from the rules based on various types of missiles and build. But that previous paragraph is enough to allow you to use the missiles in Book 2 as written.
(Note: Special Supplement 3: Missiles is part of FFE’s Classic Traveller CD-Rom collection.)
SAND
This one is easy, and what I always thought. (But, again, Book 2 does not state). From the Mayday rules:
Ships equipped with sandcasters may launch clouds of obscuring crystals (sand) which interfere with laser fire and small weapons such as missiles.
Sand may be launched in the ordnance launch phase, provided that the missiles are not launched from the ship in that phase. The launch program must be running in the computer for the sand to be hunched.
Mark the present position counter of the launching ship with a blank white counter. For as long as the ship does not change course, the counter remains in place, indicating that a cloud of sand surrounds the ship.
So, as long as the ship does not change vector the sand provides cover. If the ship changes vector, the ship ends up in one place and the sand keeps going the way it was.
Easy-peasy! But again, never defined in the Book 2 rules.
Tales to Astound! 
I need to see if the launched devices contain the launcher’s velocity. It certainly sounds like that’s what’s happening with the sand.
Yes. The missiles start at the launching ship’s vector. But upon launch can add its own propulsion to the ship’s vector to make its own vector.
Good catch. I will add that to the post.
CT77, Book 2, page 30, Ordnance Launch section, paragraph 3, sentence 3: “All ordnance which is launched has the launching ship’s vector, which must be taken into account.”
CT81, Book 2, page 32, paragraph 1, sentence 3: “All ordnance which is launched has the launching ship’s vector, which must be taken into account.”
In both versions, the term “ordnance” is constantly used to refer to both missiles and sand.
Yup. There it is. The thing that always flummoxed me was “Okay, it has the launching ship’s vector which has to be taken into account. But was is the G of the missile?” I never knew the other half of the equation.
Ha, when I saw the headline I thought you were going to delve into the ultimate Traveller mystery: the fate of the Free Trader Beowulf.
Does a 6G6 missile move speed 6 for 6 turns, or does it move speed 6 on turn 1, speed 12 on turn 2, up to speed 36 by turns 6, and then it is out of propulsion and goes straight?
The default missile movement is full thrust (6G) for six turns. That means it uses it’s full 6G every turn in order to close on itstarget.
Keep in mind that “G” is a measurement of length and direction. The missile can apply 6Gs in any direction to try to hit the target.
If it was going in a straight line every turn, then yes, every turn it would add 6Gs to its thrust and go further and further every turn. If 1G of thrust equals 100mm then on the first turn it would travel 600mm, on the second turn it would travel 1200mm, on the third turn 1800mm and so on.
However, if the missile applies it’s 6G thrust at an angle in another direction, it would add the previous vector (direction and length) it was already traveling with the new vector (direction and length) of the new thrust.
So: If a missile is traveling 1200mm forward, and applies a full 6G thrust at a right angle of its current movement, it would have a new vector about 1300mm at an angle of about 26 degrees to the right of its previous vector.
Now the new vector is 1300mm in a new direction. If the missile on the next turn applies a forward thrust of 6Gs it will move 1800mm in the same direction.
Diagrams help make this make sense! Check out the example from Book2/The Traveller Book for greater clarity.
And perhaps someone around here made a tutorial somewhere.
Sorry to comment on such an old thread, but I’ve been working through these exact questions and came across your post – your whole Out of the Box series is great, by the way, and really helpful. However, missiles do not work quite as you state, although this is not clear from either Book 2 or Mayday.
A 6G6 missile can’t accelerate to 6G for 6 turns, it can only accelerate to 6G for one turn, using all 6 of the G-burns it carries to do so. Or if it’s a type that can control it’s burn, it can accelerate by 1G for 6 turns, by 2G for three turns etc. The examples in the Missiles Supplement, page 3 under the heading ‘Propulsion Systems’ are the only place where this is made clear, it seems.
I was just trying to sort this out myself today and was surprised to see that the maneuvering thrust of missiles was never specified in the LBBs. I don’t remember being confused about it when I played hacked in the day, but it’s clearly just missing from the books. Thanks for sorting this out for me.
1g1, 3g3, and 6g6 are poor choices, vs. 1g1, 3g3, and 3g6. I still don’t know how missiles work, but if I pick up mayday I’ll have a better chance.
scratch that, sorry.