Hum, first test with stock FX torp file and new patch:
Ennemy boat 1500m right in front of me 90° angle, speed 0 in 1942;
Fired 11 torpedos ---> no one hitted boat!

(in fact 2 but were dud)
Tried magnetic position, impact position, slow speed, fast speed, medium speed, various depth...no chance.
Got about half circle ones, many premature explosions (even on circling ones for very first time!) and 2 DUD ones when hitting hull at 90°...

Think the % of defection in FX torp file has to be greatly reduced