Engineering done with slide rules? (monitor, computers, equipment, systems)

[drunk on kool aid]

Slide rules are indelibly associated with engineers and scientists of the pre-calculator era. However, slide rules are only capable of three significant digits. The use of more cumbersome log tables can give four or five place accuracy. Was all the wonderful engineering of yesteryear done using just a few place accuracy? I'm talking about early nuclear development, aircraft design, astronomy, massive civil engineering projects, etc.

Was everything checked by paper and pencil calculations or were huge, primitive computers and adding machines used? Curtas?

I'm in awe of the achievements that were made using calculating machines which would be utterly destroyed by a present-day, 99 cent calculator.

[Charles]

Mind boggling those things put a man on the moon. In nine years. While today it takes 20 years to build a space station with every engineer having Pentium 4 PCs with all sorts of modeling tools available to them on their desks.

[Submariner]

I used a slide rule in highschool and in college. I served 20+ years in the US Navy, mostly on subs where I used a slide rule routinely.

Our hull design;
sonar systems;
hydraulic plants;
the nuclear reactor;
the system that launches the missiles [they can 'throw' a missile so hard that from 150 feet underwater the missile will fly up and out of the water and then continue another 500 foot in the air, where the missile will ignite. The test the missile launch system using a 75-tonne cylinder of concrete that we throw in the air];
the missiles themselves [which fly through the atmosphere to vacuum then orbit and line-up on their first target, then after dropping the first payload they re-orient themselves onto their next target, again and again for all 14 payloads/targets];
our atmosphere monitoring systems [each gas in our atmosphere is monitored separately and dealt with separately];
Oxygen generators;
the list of amazing equipment goes on and on.

My primary system was a mainframe computer which navigates. By controlling a bunch of very accurate inertial instruments [gyros and accelerometers all on gimbals] they calculate every acceleration to derive velocities, to navigate by. But to do this we first have to map the gravity wells of the planet, and measure the gravity forces exerted on us by the sun, moon, and each planet in our system. We need to know all of these ever-changing numbers and plug them into formulas which are all dynamic, and needed to navigate underwater for months at a time. While my computer did very long formulas all the time, we had to re-check each input periodically for reasonableness to ensure the believability of the output from those formulas.

The Defense Contractor Tech-reps that assist us commonly would rotate between working on our gear and working with NASA. A lot of the same formulas are used in both situations, along with many very similar equipment.

And it was all done using slide rules.