This is the website of Gene Slover (now deceased). He was a firecontrolman in the navy back in the day. Now I don't care about the navy, nor do I really care about Gene. What I do care about is mechanical computers.

Firecontrolman in this context is the dude who operated the Mk 1 fire control computer on navy ships. Gene's website is significant to me because it has a massive amount of information on the design and operation of that computer.

It's wild to me that information this detailed is out there, cataloged by someone who actually operated the system.

Here's a short writeup that I posted elsewhere to explain why I think the computer is so cool:

The mark 1 fire control computer is an entirely mechanical computer that reads in the speed of the ship in water, the wind direction and speed, the pitch and roll from waves, the ballistic characteristics of the guns all the way down to how worn in the barrels were, and so on. Then a gun director feeds it the bearing, elevation, and distance to a target, and it does that rapidly so the computer can establish a vector.

So at one end you have a guy with a telescope/rangefinder that he points at the incoming plane, and that's all mechanically connected through a calculating machine that aims the guns the right direction, sets the fuzes to the right distance, and applies "corrections for gravity, relative wind, the magnus effect of the spinning projectile, and parallax" so that the shells explore right on a plane that zooming by.

They did all that with levers, cams, gears, mechanical integrators, etc. And they made that super complex machine reliable enough that it was used in a loss-of-life application. That's some pretty badass engineering imo

Here is a much more in depth page about it than the Wikipedia entry: https://eugeneleeslover.com/USNAVY/CHAPTER-25-C.html

And his page has a flow diagram that shows all of the inputs, intermediate quantities and outputs of the thing. I wish I could actually read them :( https://eugeneleeslover.com/USN-GUNS-AND-RANGE-TABLES/FLOW-SCHEMATIC-COMPUTER-MK-1MOD-7.html

I mean check this shit out. They had an adjustable integration step size so that you could manually adjust to balance between firing solution speed and accuracy:

The rate control system of Computer Mark 1A includes sensitivity units which control the time required by the computer to reduce errors in generated rates to the point where the corrected rates are sufficiently accurate to compute adequate gun orders. Sensitivity may be thought of as the speed with which the errors are corrected by the rate control mechanism. If the errors are corrected within a relatively short time interval, the sensitivity is considered to be high, and if the errors are corrected within a relatively long time interval, the sensitivity is considered to be low.

Blows my mind.