[pmcf]

In 1989 I was a data systems tech on a Destroyer going through some overhaul at the shipyard in Pascagoula Mississippi. Moored right next to us was the battleship Wisconsin. Huge relic from WW2 but still going through modernization. A bunch of us that worked on combat systems got invited for a tour of their fire control systems.

Wow. Just wow. All mechanical computers calculating fire control solutions for the big 16 inch guns. The guys giving the tour were well beyond the age for regular military retirement. Come to find out, they were all reactivated because practical knowledge of the mechanical computers had since left the navy. That was a very cool day.

[retrac]

By the end of WW II American torpedoes were automatically programmed (direction, speed, fusing) before firing. The heavy calculations would be done by the shipboard firing computer while the parameters set would be used by the simple computer on the torpedo (which had inertial guidance). I struggle to imagine how people managed to design such things with just pencils and slide rules.

[nine_k]

BTW these computers were mostly very functional, in the modern sense. They took inputs from instruments and controls, and computed functions, all usually continuous, smooth, real- or complex-valued. These functions' values, computed as voltages, frequencies, angles, etc were directly controlling some actuators, rudders, throttles, etc.

It's also highly compositional, as in applying relatively simple functions to results of other such functions, etc., which you can reason about analytically, and can plot on paper or an oscilloscope as a part of development and testing loop.

Disclaimer: all my hands-on experience with analog computers is from a one-semester course decades ago, using analog electronic, not mechanical devices.

[nradov]

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.

[flohofwoe]

Not exclusive to the US though, check out the "Torpedovorhalterechner" ;)

http://www.tvre.org/en/torpedo-fire-control-system-on-german...

Scrolling down there's a nice photo with removed cover.

[InDubioProRubio]

There were also a large number of captains, who refused to trust anything coming out of the navys design bureau and testing facilities and personally made sure, that computers were never used or even ripped out, to only use a "working" impact fuse. Those distrusting captains continued there "protecting the crew from dysfunctional crap" missions well up into the vietnam war. Engineering failures have serious consequences and ripple effects.

[grumpyprole]

Yes, in fact even a Harrier Jump Jet was designed with pencils and a slide rule!

[UncleOxidant]

In 1981 I was just out of high school and had a summer job at NUWES - Navel Undersea Warfare and Engineering Station in Keyport, WA. I was in a group that was refurb'ing fire control computers from submarines. They kind of looked like those stand up video game consoles that became popular in arcades soon after - except these cabinets were made of solid aluminum. They were full of gears and resolvers - analog computers. The "display" was all analog. And they were all being replaced with new gears and resolvers. I recall that there was another group nearby that was experimenting with microcomputers - they had some S-100 boxes like IMSAI 8080s.

[flavius29663]

I remember seeing one of those computers on Wisconsin, but I only saw it after decommission, as a museum piece. Those computers are truly mind boggling, if you're reading this and you're close to Norfolk you should visit battleship Wisconsin.

[ricktdotorg]

same goes for being in SoCal and going to visit the USS Iowa in San Pedro. it also has similar mechanical computers, it's a fantastic day spent clambering around the ship. sometimes they do "stay overnight in the bunks" nights, I can highly recommend it!

[cwillu]

Apropos: https://www.navalgazing.net/Fire-Control-Part-1

[zerohm]

I had a co-worker at the Navy Yard that said he was an Anti-Aircraft tech during the Korean War. When he said they used 'mechanical computers' I had to stair up into space for a minute to figure out what that meant.

[Loughla]

My uncle was on the Wisconsin and operated the big guns during the first Gulf war.

I never really had context as a kid for how large that ship is, and was just astounded by the distances they would shell.

[pmcf]

This was right before the gulf war so I may have met him! Assuming he was a gunners mate, that crew had a lot of moments of touching history. Besides mechanical computers, it’s a really dangerous place since they had to handle massive bags of flash powder.

My ship was near the USS Iowa when turret two went up. A sobering experience when you think how much risk the turret crews are in just by doing their jobs.