Torpedo launcher was a common term for systems that deploy projectiles such as torpedoes and probes. Polities known to have used such devices include the Cardassian Union, the Dominion, the Klingon Empire, the Romulan Star Empire, and the United Federation of Planets.
Hardware History
The pre-Federation Earth Starfleet already employed torpedoes and equipped the Template:ShipClass with launchers. (ENT: "Fight or Flight") Starships and installations of the Federation Starfleet also made use of torpedoes and launchers.
In 2266, the USS Enterprise encountered a Romulan vessel with a launcher capable of firing powerful plasma torpedoes. Plasma torpedoes and launchers capable of firing them would remain in the Romulan arsenal well into the 24th century. (TOS: "Balance of Terror"; DS9: "Image in the Sand")
The Template:ShipClass was equipped with torpedo launchers by 2272, and a trio of such ships made use of them in an unsuccessful strike against V'Ger that same year. (Star Trek: The Motion Picture)
By the mid-24th century, Starfleet had fielded a notably different design for its starships and installations. In addition to having a markedly longer acceleration tube it was able to launch multiple projectiles (up to 10) at once in a single salvo, an improvement from previous designs that could only launch projectile one or two at a time. This improved design was mounted on the Galaxy, Nebula and Sovereign classes. (TNG: "The Arsenal of Freedom", "Redemption II"; Star Trek: First Contact)
- It appears that by the mid-24th century Starfleet had two types of big launchers, judging from on-screen performances. The older type, with its low rate of fire (demonstrated in Star Trek VI: The Undiscovered Country), seems to have been retained for use aboard smaller ships, such as the Miranda, Excelsior, and Intrepid classes.
On the other end of the scale, the Template:ShipClass was fitted with launchers designed to fire very small projectiles, such as miniature torpedoes. (DS9: "Past Prologue")
Encounters with the Dominion before and during the Dominion War revealed that Jem'Hadar ships were also able to launch ordnance, including torpedoes purchased from the Karemma. (DS9: "Starship Down", "Valiant")
During the Dominion War the Cardassians deployed launchers aboard low-mobility weapon platforms such as those encountered in the Chin'toka system. (DS9: "Tears of the Prophets")
Background
Technical Manual
The Star Trek: The Next Generation Technical Manual suggests that the launcher systems aboard the Galaxy-class are coilguns, with each tube being served by two loaders that arm the torpedoes prior to launch. The characteristic flash that occurs when a torpedo launches has led some to speculate that the launchers maybe railguns instead. As another possibility, they could use antigravity to launch projectiles given the prevalence of such technology in the Star Trek Universe. Since the matter has never been discussed on screen, the matter is open to interpretation.