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Comment by nradov | Hacker News Reader

WW II American torpedoes didn't have inertial guidance. They used gyros for directional control and just ran in a straight line after making a single turn onto the set course. Occasionally the torpedo would get stuck in that turn and run in a circle. Towards the end of the war the Navy also started introducing homing torpedoes, but those didn't use inertial guidance either.

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> 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...

Clear the Bridge [0] was an autobiographical account of WW2 from the captain of the Tang. O'Kane covers the experience of this incident in the book.

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...

This may have been common enough that I distinctly remember it as something that could happen when playing Sub Battle Simulator in ‘91 (or around that year): https://en.wikipedia.org/wiki/Sub_Battle_Simulator

A gyro by definition IS inertial guidance.

Not really. By definition an inertial guidance or navigation system has to do some sort of integration of inputs over time. Gyroscopes are typically used as part of inertial guidance systems, but connecting a gyro output directly to a rudder input wouldn't by itself be considered as inertial guidance. The device wasn't doing anything to calculate absolute position based on inertia.

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