Photon torpedo vs. phasers - what is the use of both in-universe

Question

Watching Star Trek I've observed that phasers and photon torpedos are used interchangeably and seemingly at random. I know that probably writers didn't think/care but I look for explanation in universe.

The presence of 2 weapons in single vehicle is usually justify by different targets and use, say machine gun for soft targets (infantry) and main gun for hard ones (other tanks). Otherwise it only increase problems (incompatible ammunition, increased maintenance cost etc.). So what are the differences between those two?

Answer 1

One is energy-based (phasers) and the other is matter-based (torpedoes) with an explosive yield. I remember reading once that it in a confrontational situation, the phasers would typically be used to weaken another ship's shields and then the torpedoes would finish the target off.
Also the phasers were used more to disable ships than to destroy them, as they could target more precisely.

Answer 2

According to the Technical Manual phasers are constrained to the speed of light so are of less use in confrontations that are taking place under warp drive. Photon torpedoes have warp capability (though not full warp drives) and so can go faster than light speed and engages ships also doing so.

Also photon torpedoes can be used as mines which phasers can not.

Answer 3

I suspect there is a desire on the part of the writers to have an analogy to pre aircraftcarrier battleship fighting. Phasers are like deck guns, and torpedos, are like their namesake. One has longer range, and is quicker to aim, and the other is slower, but does more damage. Most spacewar stuff, wants to reenact war world two battles, either naval, or bombers versus fighter planes.

Answer 4

It is mentioned several times in Voyager that photon torpedoes are irreplaceable. Although fans have counted the number of photon torpedoes fired throughout the entire series and found it to be much higher than the number given explicitly in one of the first episodes, it nonetheless provides an in-universe reason not to want to waste them.

Answer 5

Another good reason to use them differently is that torpedoes can track a target where as a phaser is fired directly. If it misses, it misses. If you recall, one of the movies, a Klingon ship is cloaked but leaking particles (photons was it?) and they modified a torpedo to run the particles down to the source to kill the ship.

Answer 6

I know this a technical discussion about different capabilities, but phasers have become progressivly less powerful as the series progressed from Star Trek to Voyager. In the original series, where the plots were written by classic sf writers from the golden age of sf, and as such were dense with new sf concepts, there is some discussion about how vastly powerful they are. I don't know the episode, but it is about two humans who crash landed and were badly damaged and the aliens allow them to be viewed as complete and unbroken.

In that episode, they need to break into the underground fortress (it was the episode with the lift underground); they use a tripod phaser, which is really powerful. They say that it 'should have blown the hill in seconds' even though the telepathic aliens are generating an image in the crew's minds of an unbroken hill at that point.

The point is, Kirk discusses firing the phasers from space, but they're worried (if you read the script) that the phasers are going to really destroy everything, cutting into the planet down to the core, and even destroying it, cutting it in half. Those were super power cutting beams that are vastly powerful, unimaginably fed by antimatter engines.

Contrast that by the time of Voyager. Phasers can't even penetrate shielded hulls or borg. I know I'm harping, but comparatively, if the Enteprise met the Borg, they would slice the cube into bits.

The whole progression of the series has softened it from a sf series into a script with spaces for sf words. Choose a word.

Answer 7

Phasers and torpedoes are, as was mentioned, much like deck guns and torpedoes in WWII-era naval warfare. The idea of the Klingon and Romulan warbirds being able to cloak and thus be hidden was a direct analog to the German U-boats.

Tactically speaking, you want as many types of weapons as you can get when you're in a fight. This applies virtually across the board, in all situations. If one weapon doesn't suit the situation, you bring another. It's why police officers don't just have guns, but batons, tasers and pepper spray as well.

Back in-universe, phasers are the go-to weapon. Phasers are energy-based, meaning as long as you have sufficient power you can continue to fire them. They are very powerful against most unshielded targets, and can be brought to bear from nearly 360 degrees (provided all phaser banks are operating nominally). Lastly, being a beam, they can usually be aimed and fired pretty quickly at a target at almost any renge at which the weapon is effective (even right up close). However, depending on the race's level of technological advancement, phasers often have minimal effect on shields or even ship hulls. They are also limited by the speed of light, so they cannot be used while travelling at warp.

Torpedoes are the Star Trek equivalent to the same weapons in naval combat, or to anti-ship missiles like the Harpoon or Exocet. Get hit with one of these with your shields down and your ship has a big gaping hole in it. The explosion also requires a lot of shield power to repel and can cause damage even with shields up. They also require minimal power to fire, making them the principal weapon of cloaked ships like the Klingon Bird of Prey, and they can be used while the ship is travelling at warp, as they maintain a "warp bubble" generated by the firing ship. However, they are an expendable weapon; it is implied that torpedoes are too complex a machine to replicate, even without their antimatter payload. They are also, for the most-part, non-seeking; they must be given their initial guidance from the firing ship, and if the "sight picture" changes (the ship radically changes course or speed) the torpedo can miss. Torps have a maximum rate of turn and come out of the launcher along the fore-to-aft axis of most ships in the universe (there are a few turreted launchers), meaning their effectiveness in a "broadside" confrontation is reduced. This makes torpedoes a weapon you use in head-on combat when you are pretty confident that you will hit your target, usually meaning relatively close range.