Earlier quoted context omitted.
> Occasionally the torpedo would get stuck in that turn and run in a circle. Well that's not a great failure mode, if it can come right back at vessel which launched it ... imagine trying to implement a self-destruct failsafe with that tech back then ...
At least two US Navy submarines were sunk by their own torpedoes making circular runs. The main failsafe mechanism disabled the detonators until the weapon had run out a certain minimum distance but obviously that wasn't effective in circular runs. https://www.usni.org/magazines/naval-history-magazine/2011/j...
While two US Navy subs were known to be sunk in this manner, there remain several subs not claimed by either Germany or Japan that just never returned.
0 - https://www.amazon.com/Clear-Bridge-Patrols-U-S-S-Tang/dp/08...