Torpedoes are slow but incredibly powerful missiles, which pack enough damage to destroy whole capital ships but are too slow to hit fighters. Torpedoes are mounted in the cruise disruptor/ torpedo mount. Only very heavy fighters and heavy fighter are able to carry the torpedo mount. Like all disposable items there are limited to 50 rounds.
Be careful not to accelerate sharply after firing a torpedo, it's entirely possible to catch up to your own torpedo and blow yourself up.