I've got a video for you in which I have torps change their momentum in unexpected and weird ways. Should be easy enough to reproduce.
- Equip RZBs with torps
- fly attack vector longer than 7km
- manually drop torps with a few seconds' separation
- check their momentum before activation.
- wait for activation
- watch them go haywire not always, but very frequently.
I can't tell you what causes it.