I don't believe torpedo speed should be a factor in wirebreak. The wire unreels from the torpedo and should be stationary in the water even when the torp is at max speed -- at least, one would hope the designers spec'ed the reel mechanism to work at max torp speed.
The sub is where the problem is. The wire unreels from the breech-end of the tube as the sub travels through the water, thus it stretches through the torpedo tube and past the muzzle and outer doors. Theoretically, the wire should be stationary in the water as the sub maneuvers. However, high speeds and/or turn rates can cause the wire to 'snag' at the muzzle/outer door and break.
Can make wire break dependent only on sub speed, turn rate* (use rudder angle?) and distance from the launch point?
*Actually, wire break will depend on magnitude of turn from original launch heading, and is more likely if the sub turns in a direction away from the side the torpedo's initial run-out course.
Complicated, ain't it?
