this post was submitted on 11 Oct 2024

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Slide Rule (sh.itjust.works)

submitted 1 month ago by Estiar to c/[email protected]

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I gotta post something, so I'll post the mechanical calculator that the flight school wanted me to get. How it works is that you can set ratios in the dial and multiply them. In this picture, it's 60:10 (or 60:1.0) so I can take any number from the inner circle in minutes and find out how many hours that is equal to on the outer circle.

There are also other things on this calculator, including a wind vector calculator, and charts. Most pilots don't use these anymore, but they still wanted me to know how to use one

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[–] [email protected] 26 points 1 month ago (1 children)

Not just ANY calculator. But something that will literally save your life when the electrics on the plane are blown and you need to get to that little airport via dead reckoning.

[–] [email protected] 2 points 1 month ago (1 children)

I wonder if we’ve semi automated some way to make arbitrary slide rules. Like some kind of software that you punch your functions into, or some table of info to be interpolated, and it lines everything up.

[–] Tar_alcaran 2 points 1 month ago (2 children)

I wonder if we’ve semi automated some way to make arbitrary slide rules.

This is how a lot of maths is already done by computers. For example, it's basically impossible to get a computer to do an integral of an arbitrary function, but there are a lot of methods to approximate the answers. And that's mostly by using "slide rule" methods of approximately getting the right answer. The computer just does it fast with smaller intervals than you'd do manually.

[–] [email protected] 1 points 1 month ago* (last edited 1 month ago)

There's a bit of a difference though between those computer driven iterative digital numerical methods and an analog continuous geometric object. It's like comparing pixel density and film grain. At a fine enough precision they become difficult to distinguish, but they are not the same. You could definitely use iterative methods to build a "continuous" solver at an arbitrary precision. We pretty much have to do it that way for any signficantly complex function.

Sorry, this comment got away from me and feels kind of incoherent now. I'm just trying to say that analog and iterative digital methods have subtle differences that one should remain aware of.

[–] [email protected] 1 points 1 month ago (1 children)

I’m aware of how computers use numerical methods to get numbers that are good enough for a given precision.

I meant more like a robust way to create physical slide rules for arbitrary uses. Here’s a set of tables of baking ratios, I want to comfortably look up x for a known y. That kind of thing.

[–] Tar_alcaran 2 points 1 month ago

I think what you really want is nomogram, which is like a non-moving sliderule in the form of a graph, which is great for "If I have X of thing A, and Y of thing B, how much of thing C do I get/need?" questions like baking ratios.

Unforuntately, I can't really find an nomogram generators online that I can get to work (though that might be a me-problem, and not a website problem)

[–] [email protected] 22 points 1 month ago (1 children)

Flight computer

Can it run doom?? :)

[–] [email protected] 2 points 1 month ago

It can plot a course for Mount Doom

[–] [email protected] 9 points 1 month ago (1 children)

Hey.... do yourself a favor and get a CX-3 flight computer. They're allowed on the written. Don't worry, you can thank me later 😜

[–] Estiar 1 points 1 month ago

It's in my to do list to buy

[–] [email protected] 9 points 1 month ago

I hate these things with a passion. When I did flight school my instructor made me use one nonstop. I've never used it since but I still being it as a backup

[–] [email protected] 6 points 1 month ago (1 children)

And you will never use it again after your ppl. Thank god!

[–] [email protected] 8 points 1 month ago (1 children)

For every useless thing I learned in college, it at least had a decent reason to be in the curriculum, whether because it provided historical context to what I actually work with or because it provided a strong mental model to understand what the programs that automagically do the work for you are actually doing behind the scenes which is invaluable when troubleshooting edgecases and failures

[–] [email protected] 4 points 1 month ago

In my experience, this is one of the devices that only creates more confusion in what already is a high stress environement. I get what you are saying, but i doubt there is a single pilot under the age of 60 that would ever use this device willingly. The heirarchy anymore is the in suite avionics, then secondary instruments, then Ipad, then, asking for vectors.

Its like an abacus. Theres just very little use for it anymore. And maintaining proficiency is only for the test.

[–] brown567 5 points 1 month ago

I freaking love mechanical calculators!

[–] [email protected] 4 points 1 month ago

That's the same one I have, even here in Australia.

Awesome piece of kit

[–] [email protected] 3 points 1 month ago

I have the same one. Still useful for density altitude, TAS, and time distance calculations. I still use it after all these years. Not the wind chart though. Fuck that noise!

[–] [email protected] 1 points 1 month ago* (last edited 1 month ago)

I've got a very rudimentary version of that on my watch! I didn't specifically want an aviation watch, just something radio controlled, solar powered, and resilient. This one is made with titanium and has sapphire instead of glass.

ETA: I've read the manual and a few articles on how to use the damn thing and I still don't get it. I usually forget that part of the display rotates with a dial.