Photons

Photons in Star Trek

The photon torpedo is a guided, warp capable weapon with an anti-matter war head.  Although the guidance in the films and series is never really seen, the best example is in the Undiscovered County finale battle with the cloaked BOP.  The guidance of the torpedo generally is pretty poor but it needs some sort of guidance to be a warp capable weapon.  It's a weapon formed by various plots over the years that has not been that consistent. The Undiscovered Country and Mutara Nebula duel in TWOK are probably the best two examples to use as a basis for gaming. 

For an anti-matter warhead the results are fairly weak as well, the best example are the way the shields of the Enterprise get rapidly depleted in Undiscovered Country and the  torpedo yield blows a hole in the saucer.  These are penetrating weapons and should have a hefty payload. For accuracy we look at TWOK where the Reliant misses the Enterprise (on purpose) as it enter the nebula. These are very long range weapons but their accuracy falls off with range.

Full Thrust

The pulse torpedo in Full Thrust is a direct implementation of the photon. 

A Pulse Torpedo launcher tires a bolt of plasma contained with a gravitic field, which is able to punch through Screens and cause significant damage to any target. Torpedo launchers may be mounted to fire through the FORE arc of a ship ONLY. Each launcher may fire one Torpedo per game-turn; engaging a target with Torpedoes requires the use of one Fire Control system, which may NOT also be used to direct Beam Batteries that turn, even at the same target.

Pulse Torpedoes have a maximum range of 24". One D6 is rolled per Torpedo fired, and hits are scored on the following rolls:

At range of:

0-6" Required score to hit: 3 to 6

6-12" Required score to hit: 4to 6

12-18" Required score to hit: 5 or 6

18-24" Required score to hit: 6 only

For each Torpedo that successfully hits the target ship, roll a second D6: the result is the number of Damage Points inflicted on the target (ie: from 1 to 6 pointsl. Note that Screens do NOT reduce the damage done by Torpedo hits.

There are as few issues with this weapon as described, need for a separate firecon isn't seen in Star Trek but they need a sensor lock. They also don't ignore shields. The range is also too low for a warp capable weapon.

We could have used the normal missile but they are slow and bulky and expensive and the photon magazine of a cruiser is 200, they are not a good fit.

Fleet Book

The salvo missile is similar to how a photo behaves. But the rules are too complex  on book keeping and we would need a near limitless magazine.

Cross Dimensions

Adds range classes to the torpedoes 

Torpedoes in CROSS DIMENSIONS now have numeric classes. The default is 1, which was the only class in the original edition of FULL THRUST.

Each extra class above 1 adds 3 MU to the torpedo range bands, so a class-2 torpedo hits on a roll of 2 at range 0- 9, 3 at range 9-18, and so on up to 6 at range 36-45. The damage for all classes of torpedo remains at 1D6.

Range classes not really a thing in Star Trek.

Project continuum

Adds pulse torpedoes (SAP) pp 41

Pulse Torpedoes are one of the most common projectile weapons in use. At short range they are very accurate, and a lucky hit can deliver a large amount of damage. Pulse Torpedoes are Semi-Armor piercing weapons.

As a projectile weapon, Pulse Torpedoes ignore Standard Screens. If a Pulse Torpedo hits, it inflicts 1d6 point of damage, Semi-Armor piercing (SAP). The chance of a hit decreases with range.

These are sort of correct apart from the no effect against shields as clear in Star Trek shields stop them to some degree. In this case standard screens would not be a good substitute for a Star Trek shield.  Continuum adds more types too. Standard, long & short range. 

There are more types overloaded pulse torpedoes getting a bit Starfleet Battles like, has a greater yield & damage. Variable strength pulse torpedoes allow the ability to fire long, short or standard range shots. This range limit doesn't appear in Star Trek.

The rules are getting quite complex with overloaded weapons exploding and setting the range setting for the variable types.

Discussion

So in summary pulse torpedoes are probably the best starting point. But there need to be some changes. 

The weapon should seek as it's a missile. If you have a sensor lock it should only miss if you lose the lock or the target evades or there are atmospheric conditions like the Mutara Nebula.

The weapon should be very long ranged and warp capable. The weapon should be stopped by shields or be leaky as in the battle in Star Trek VI. A direct hit from a photon with no shields should take out most of your ship for example in Star Trek II the reliant loses a whole nacelle. Two or three hits and it's game over without shields unless its a very large ship. Cruisers and destroyers will be coming apart after a couple of direct non-shielded hits.

There should be a way to set a proximity photon as seen in Balance of Terror, they aren't really phasers. The proximity photon needs a point of aim and a blast radius, similar to a salvo missile.

As to types normal anti-matter and quantum are two we see most commonly. Each type should have a proximity setting. The quantum torpedo should have a yield of at least double a normal anti-matter warhead as it uses a quantum singularity as its warhead.