The torpedoes that this launches keep the lateral momentum from the ship that fires them, meaning if you fire them while you are strafing the ship, they will have horizontal momentum that you need to compensate for while aiming. Some players find it useful to decelerate while flying directly towards the target (C + W) in order to nullify any relatively sideways movement. Reaper torpedoes have a 0.5 second arming time so firing at point blank will cause them to bounce, unpredictably.
Only up to date for version 0.96. It is likely still broadly correct but not verified for the most up to date data yet. Please double check the Version History.