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Old April 25th, 2009, 11:23 PM
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Default Perspective on Traveller Space Combat

While participating in this thread, , I wrote the post below. It's a bit of a detour from the OP in that thread (which centered around High Guard and not Book 2 space combat), and I think some of the concepts I mention about the reality of Traveller space combat may be worth further discussion.

I'm guessing that not every Traveller GM has thought about Book 2 space combat in quite this way.

The remark I was replying to stated that ship "facing" is not an issue in Book 2 combat. I agreed, with these comments....

Yep. They figure 1000 seconds is enough time for the ship's thrusters to angle the ship in any direction, so facing is not an issue.

Plus, a ship can roll (which is probably what's done) without actually changing facing, bringing weapons to bear.

For example, a ship is traveling left to right across your bow. The weapons turret is on the dorsal side of the vessel, but you are observing the ventral side. All the ship needs to do is roll along its axis, bringing the dorsal side to bear on you, and the vessel's vector is never really changed. It's still moving in the same direction at the same speed.

Things get a little more dicey when the ship coming at your, bow on, or you are chasing a vessel, observing it's aft section. Still, the way most Traveller designs I've seen in illos. shows a turret that has a good field of vision fore and aft.

For this reason, actual ship's facing is a detail that isn't worth the trouble during Book 2 space combat (with Range Bands).

I would like to note, though, that when space combat is carried out, it is usually carried out at a low vector (low speed).

For example, using Range Bands, a ship with a Vector of 3 is moving 3 Range Bands (30,000 km) per turn. Let's say the ship's Captain decides to reverse course and return to where it came from. If that ship is rated with a M-1 drive, it will take that vessel just 3 space combat turns to bring the ship to velocity 0 and another turn to accelerate to velocity 1. (4000 seconds to "slow down" from traveling 30,000 km in one direction, reversing course, to a speed of 10,000 km per turn in the opposite direction.)

Just think of a combat scenario where the ship becomes engaged with an enemy when the ship is at a very high velocity.

For example, let's say a ship, with an M-1 drive, is done with its planetary duties and heads out to the nearest gas giant to refuel before jumping to the next world.

Just using the easy numbers from the Typical Travel Times chart, a close gas giant is 600,000,000 km away. It will take the M-1 ship 136.1 hours to make that journey.

Consider that, for 68.5 hours, the ship will be accelerating at maximum thrust, then, it will flip around, and travel "backwards", using it's drives to decelerate for another 68.5 hours (GMs should remember that it shouldn't be uncomon at all to see vessels traveling "backwards" in systems).

Let's say that the ship is attacked at 60 hours out from the main world. Just how fast is the ship traveling at that point?

A space combat turn is 1000 seconds. 60 hours is 216,000 seconds. So, what we're saying is that the ship has accelerated, constantly, in a straight line, for 216 space combat rounds.

That means the ship's velocity, in space combat turns, is 216 at that point (provided the ship started at velocity 0): That means the ship is traveling 2,160,000 km per turn. Guess how long it will take this ship to decelerate to a relative stop and start accelerating in the opposite direction (as I used in the example above)? That's right. 60 hours. Meaning: It ain't gonna happen any time soon.

(To put this speed in perspective: The farthest Earth-Moon distance is 405,696 km. The ship, with an M-1 drive, will be traveling over 5 times this distance in just over 15 minutes. Now, go outside at night. Look at the moon. See how far away it is. Then imagine 5 times that distance. NOW you get a grasp on just how fast our little M-1 drive ship is traveling after 60 hours of thrust.)

That's a hell of a speed. And, an M-1 drive can only alter that course by 10,000 km each 1000 second combat turn.

Effectively, if the ship is attacked 60 hours into its journey, the ship is traveling basically in a straight line, and there's not much the crew of the ship can do about it even if they wanted/had to.

That's the bad news.

The good news is that any pirate vessel looking to intercept the ship will have to match vectors, using its drive, and will essentially be traveling in a straight line also at this high rate of speed. More good news is that the ship will see the pirates coming on sensors long before the pirates accomplish their task of matching vectors.

On the other hand, the ship will be able to do little to stop the pirates from coming even though the pirates have been detected.

In this sense, Traveller space combat is a lot like 17-18th century sailing ships. They see each other coming for a long time, and then they start firing on each other when either reaches weapons range.

If you think about the above scenario, the ship and the pirate vessel will match vectors and just take pop shots at each other, just like going "broadsides" with old sailing vessels.

Maneuverability and weapon class are key to Traveller combat. If the pirate vessel is rated at M-3, and the ship is rated at M-1, this gives the pirates the ability to approach quicker (they'll still be seen coming) and get out of the situation quicker (as they should, the pirate vessel is 3 times more maneuverable).

As far as "facing goes", the ship can just shut off the drives, and use the attitude thrusters to face the ship in any direction desired (so, facing, again, is not an issue), but the direction of thrust and speed of the vessel will remain the same, no matter which way the bow is facing.

So, yes, really, "facing" is not really a factor. Range Bands do handle it well because, well, Range is all that we're really talking about. You don't need plots, 2-D or 3-D, because it's all about range.

Last edited by Supplement Four; April 25th, 2009 at 11:27 PM..
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