Not exclusive to the US though, check out the "Torpedovorhalterechner" ;) http://www.tvre.org/en/torpedo-fire-control-system-on-german-u-boats http://www.tvre.

Not exclusive to the US though, check out the "Torpedovorhalterechner" ;) http://www.tvre.org/en/torpedo-fire-control-system-on-german-u-boats http://www.tvre.org/en/torpedo-fire-control-system-on-german... Scrolling down there's a nice photo with removed cover.