Torpedoes are quite vulnerable to surface gunfire when they run on the surface, like the ones in SimplePlanes do. I would request a depth setting that can be adjusted through the parts settings menu.

The minimum depth is surface running, and the deepest it should run is 50 feet.
The whole reason why torpedes were extremely effective is because the enemy couldn't out-run them, and they couldn;t see the actual torpedo because it was running below the surface.