## Thrust and Movement in combat

Discuss the Traveller RPG and its many settings
JNJ
Stoat
Posts: 58
Joined: Tue Mar 13, 2018 4:01 pm

### Thrust and Movement in combat

Hi,

It is said in the space combat chapter that :

"In order of initiative, each ship can allocate Thrust to
either movement (closing or increasing the range between
it and another ship) or combat manoeuvring (docking with
another vessel, lining up a shot or dodging incoming fire)."

My question is : If a ship allocates 1 Thrust point in the 1st round and 0 in the 2nd round, does't it means it "stops" in the 2nd round ? = 0 move

Should'nt it be more logical in space that he keeps is 1 Thrust momentum, even if not allocating another point in round 2 ?

Thanks for your help.
JN
mac40k
Shrew
Posts: 24
Joined: Thu Mar 01, 2018 12:04 am

### Re: Thrust and Movement in combat

The ship continues to move, but without applying additional thrust it isn't doing anything to actively close or increase the range between it and another ship/object. So if you are chasing a ship after round one, you still are in round two, but aren't continuing to close the gap and may actually get further away if the other ship continues to apply thrust to open the gap.
JNJ
Stoat
Posts: 58
Joined: Tue Mar 13, 2018 4:01 pm

### Re: Thrust and Movement in combat

Hi Mac40K,

Seems an acceptable explanation. Thanks

JN
AnotherDilbert
Cosmic Mongoose
Posts: 4253
Joined: Wed Dec 23, 2015 2:49 pm
Location: Sweden

### Re: Thrust and Movement in combat

"Thrust" is acceleration, not speed. A ship will, like an ice-hockey puck, continue with the same speed until someone whacks it (applies thrust).

As Mac40k says, if both ships continue with the same speed the range will not change, even if both ships continue to travel at roughly the same speed in roughly the same direction.

The range band system is highly simplified so that we do not need to keep track of ships' exact positions and velocity vectors, just a rough relative position. More accurate, but also more complex, models can easily be used, e.g. a one dimensional vector system where we keep track of relative position and each ship's speed toward or away from the enemy (thrust is then change in speed).
JNJ
Stoat
Posts: 58
Joined: Tue Mar 13, 2018 4:01 pm

### Re: Thrust and Movement in combat

Ok, seems clear when ships are going in the same direction.
But what if they are going in opposite dfirection (both are going toward the other one to decrease range between them) ? As both continue with the same speed, range should decrease by this factor each round even if not appliying more thrust ?
So to go back to the rules, if both have 1 thrust in round 1, and none applies extra thrust points in round 2 :
- If going the same direction, distance stays the same.
- If going toward each other, distance should decrease by 2 points as they both keep momentum ? (that's my question)

MonkeyX
Banded Mongoose
Posts: 203
Joined: Wed Feb 21, 2018 11:52 am

### Re: Thrust and Movement in combat

I’d say if you don’t use Thrust the the position stays as it was. Assume the ships perform loops and other trick in the same band and don’t get any closer. I found this space combat track incredibly handy. http://www.rpgnow.com/product/193820/Mg ... =161_25550
Condottiere
Warlord Mongoose
Posts: 8307
Joined: Mon Sep 23, 2013 8:23 pm

### Re: Thrust and Movement in combat

It's abstract; the assumption at the start of battle is that both sides orientate themselves towards each other.

Logic tells you that it's a moving battlefield, and that slower ships, or ships knocked out are going to drift off as the front shifts, which would be far more likely for smallcraft.

If both commanders decide to furball, everything gravitates towards the middle.

If I had a battlecruiser centric force against one with battleships, I'd keep the range open.
AnotherDilbert
Cosmic Mongoose
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Joined: Wed Dec 23, 2015 2:49 pm
Location: Sweden

### Re: Thrust and Movement in combat

MonkeyX wrote: I’d say if you don’t use Thrust the the position stays as it was. Assume the ships perform loops and other trick in the same band and don’t get any closer.
A ship can't change speed or direction without using thrust.
https://en.wikipedia.org/wiki/Newton%27 ... _first_law

Making a loop takes an atmosphere and wings or lots of thrust.

Think of two cars travelling along a road, as long as neither accelerates the distance between the cars will not change much despite both cars continue to travel. It's not a perfect analogy nor is it a perfect system, but it is simple.
JNJ
Stoat
Posts: 58
Joined: Tue Mar 13, 2018 4:01 pm

### Re: Thrust and Movement in combat

Simple system and I think mostly adapted for small fights between 2, 3 ships with a strong narrative side.

That said, I checked meanwhile LBB2, Mayday and Intercept and I think I will use vectors and map for space combat.
It's quite simple also, can handle any kind of combat, and answers above questions.

It also keeps the "wargame/boardgame" part of Traveller which I find great...going from wargame to RPG and back. I like to imagine Traveller like this.