Impulse

Impulse drives in Star Trek

Impulse drive in Star Trek is used for tactical movement. Most of the battles are at impulse, though there are warp battles in several TOS and TNG episodes.  The canonical impulse battle has to be TWOK in the Mutara Nebula.  Here the ships move on impulse power and we see that they turn not nimbly but quite slowly, the Enterprise sweeping in to the 6 o'clock of the Reliant. 

For big ship battles the best are in DS9 Sacrifce of Angels and Tears  of the Prophets. To be honest most of the DS9 battles the big ships lumber in and just slug it out. While the more nimble ships weave in and out.

IAnother good example is Prelude to Axanar where the impulse battles though at close quarters are well choreographed. There are several Axanar battles that never made release that are worth checking out.

So we are looking for a system that has this sort of feel for Full Thrust. There are two sub-light manoeuvring systems cinematic and vector movement. The vector system is nothing like Star Trek so we will focus on cinematic. 

In FULL THRUST RULES

Full Thrust - page 6

The normal cinematic movement system allows you to use half your thrust rating for turning rounded up.

The THRUST RATING of a given ship is the TOTAL maximum amount of Thrust that may be applied in any one Game Turn. In one Turn, ANY OR ALL of the available Thrust may be used to change the ship's VELOCITY (up or down, to accelerate or decelerate the ship), but only up to HALF the THRUST RATING may be applied to COURSE CHANGING; in other words, a ship with a THRUST RATING of 4 could accelerate or decelerate by up to 4" per Game Turn, or could apply up to 2 points of Thrust to Course changes and still be able to make a 2" change to velocity in the same turn. The ship CANNOT however, apply MORE than 2 of its available Thrust points to changing Course.

Fleet Book - Page 5

Fleet Book introduces vector movement, rolling ships and rounding odd thrust down for course changes. The rolling of ships is supported for StarTrek as a lot of the battle scenes have ships rolling see DS9 in particular.

Rolling Ships

Although FT makes no attempt to simulate 3-dimensional movement or combat (as explained in the FT rulebook, we feel that the additional complication far outweighs the benefits gained), there is one simple rule addition that we are including here: the ability to “roll” a ship 180 degrees on its central axis, thus effectively swapping the port and starboard sides (the ship is “upside down” relative to the other ships on the table). This manoeuvre can be very useful when ships start to lose systems due to damage, as it can allow undamaged weaponry to bear on targets that would otherwise be on the wrong side of the ship. To perform a roll, the player simply notes RO in his movement orders for that turn; the roll expends 1 thrust factor, which comes off the “turning” allowance - i.e.: a thrust-4 ship, normally capable of 2 points of turn, could only turn 1 point if it also rolled that move (but it would still be able to use its other two thrust factors to accelerate or decelerate as normal). The roll then occurs at the start of the ship’s movement, and a “rolled” marker is placed by the model to indicate its inverted condition. Rolling has no effect on combat EXCEPT that the ship’s port batteries now bear to starboard, and viceversa. An inverted ship may, of course, roll back “upright” in any subsequent turn, or may remain inverted as long as the player wishes. For simplicity of play, it is suggested that rolled ships should still have their movement orders written in relation to the actual miniature rather than their theoretical inverted condition - thus an order written for a Port turn will still turn the model to the left, even though to the inverted ship this would actually be a “starboard” turn. Keeping to this convention should, hopefully, avoid a lot of potential confusion and arguments!

ODD-NUMBERED THRUST FACTORS

It is permitted to design ships with odd-numbered Thrust factors (eg: Thrust-3); such drives operate just as for even-numbered ones except that to determine the thrust available for course changes the thrust rating is halved (as normal) but is rounded DOWN, so that a ship with Thrust-5 is only capable of 2 points of course change. Note, however, that ships which (through design or through drive damage) have a Thrust factor of 1 may always change course by 1 point per turn, but may not accelerate or decelerate at all while doing so.

My feeling is that the rounding down makes Star Trek ships too sluggish and we should follow the original FT rules or make them even more nimble.

Full Thrust Warlords - Page 6

Has the same movement rules as the Fleet Book and rounds down odd number turns for thrust.

Full Thrust Cross Dimensions - Page 20

Full Thrust Continuum - Page 21

Has the same Fleet book rules but introduces advanced drives. 

Unusual species or ships may be capable of amazing spins and turns due to their advanced drives. These are rare: it is not enough for such ships to be more agile than others, but to be able to perform manoeuvres impossible to normal ships. To differentiate advanced drives from normal drives, a slightly different symbol is used on the System Status Display, and when the thrust rating of an advanced drive is written down it is suffixed by an “A” to indicate that the advanced drive rules should be used. Ships with advanced main drives move and manoeuvre in exactly the same way as other ships with one exception: they are permitted to use up to all of their thrust rating to change course instead of half. A ship with an advanced drive with a thrust rating of 6 could actually make a full 180°aboutface in a single turn, though its path would in fact be an L-shaped manoeuvre rather than a turn in place, as it is still bound by the normal rules about splitting course changes between the start and midpoint of the movement.

These would be unbalancing against normal ships but if all Star Trek background ships have them then it would not. It therefore seems that the Star Trek impulse drive is best based on the advanced drive.