Detailed articles on the avionics of NASA’s space shuttle(spaceflight.nasa.gov)
spaceflight.nasa.gov
Detailed articles on the avionics of NASA’s space shuttle
https://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/avionics/
13 comments
From the second link,
>Interestingly the indicators are incandescent bulbs…
>an odd choice as they have used LEDs as indicators on the PCBs as we will see later.
Lightbulbs have well-understood failure mode (open circuit) and detection of such failures; it's exceedingly rare for a lightbulb to fail half-way. Contrast that with LEDs which can fail while remaining as either open or closed circuit. This (costly & lengthy airworthiness certification aside) is why even modern airliners use lightbulbs for avionics indicators - often in redundant pairs. One of very few maintenance items commercial pilots are allowed, and indeed trained, to perform routinely is replacing the indicator lighbulbs.
In-depth coverage by Mentour Pilot: https://www.youtube.com/watch?v=RifyTCwwNy0
>Interestingly the indicators are incandescent bulbs…
>an odd choice as they have used LEDs as indicators on the PCBs as we will see later.
Lightbulbs have well-understood failure mode (open circuit) and detection of such failures; it's exceedingly rare for a lightbulb to fail half-way. Contrast that with LEDs which can fail while remaining as either open or closed circuit. This (costly & lengthy airworthiness certification aside) is why even modern airliners use lightbulbs for avionics indicators - often in redundant pairs. One of very few maintenance items commercial pilots are allowed, and indeed trained, to perform routinely is replacing the indicator lighbulbs.
In-depth coverage by Mentour Pilot: https://www.youtube.com/watch?v=RifyTCwwNy0
TIL!
For a few seconds I started thinking about packaging LEDs with onboard LDRs so any failure that results in not-100%-light-output produces an open circuit... but I can see the result having too many moving parts to comfortably pass certification. If such a thing is even possible to make.
Your mention that LEDs can fail closed rules out a current-consumption monitoring system...
And then a "light up all the indicator lights" button (which IIRC does exist?) connected to a camera and machine vision system would _work_, but it'd probably be a ton more expensive (to build _properly_) than just sticking with incandescent bulbs.
For a few seconds I started thinking about packaging LEDs with onboard LDRs so any failure that results in not-100%-light-output produces an open circuit... but I can see the result having too many moving parts to comfortably pass certification. If such a thing is even possible to make.
Your mention that LEDs can fail closed rules out a current-consumption monitoring system...
And then a "light up all the indicator lights" button (which IIRC does exist?) connected to a camera and machine vision system would _work_, but it'd probably be a ton more expensive (to build _properly_) than just sticking with incandescent bulbs.
> I like fonts from old things :/
You are not alone my friend. I also have now taken a local copy of that font test jpg :)
You are not alone my friend. I also have now taken a local copy of that font test jpg :)
The vertical mounting of the CRT is interesting. Any idea what that decision was made? These things obviously would not have a lot of high motion to display/refresh, but it's such an unnatural feeling thing to do, at least to a video enginer's way of thinking.
My guess is
- to fit within the bounds of the space allocated within the cockpit dashboard
- to fit enough information on the screen so the end result isn't cramped
- to possibly take advantage of an existing CRT assembly that already existed somewhere in the world, so they weren't commissioning a custom design (and the tooling required)
- to fit within the bounds of the space allocated within the cockpit dashboard
- to fit enough information on the screen so the end result isn't cramped
- to possibly take advantage of an existing CRT assembly that already existed somewhere in the world, so they weren't commissioning a custom design (and the tooling required)
Wow this covers a lot of my job, and is really concise and well written.
This might be the best link ever posted to HN for me. Thank you.
This might be the best link ever posted to HN for me. Thank you.
What kind of job do you do? My vague guess is NASA historian or tour guide.
These articles would be of interest to anyone developing flight avionics systems for spacecraft, airplanes, or, I can imagine, drones.
Yea flight avionics, sort of. Aerial camera systems and the UI to control them.
Wow, that sounds really cool.
I really like the UI design that goes into avionics - the fact that every possible scenario has to be thought out and handled, and that the end result has no flashy eyecandy or extraneous functionality; it's all function, it's all required (or it's not there); everything on the screen at any given time is significant, and (hopefully) care is taken that the amount of data (ie, significance) showing at any one moment is not information overload. A very hard balance to get right, I'm sure.
The rigor and discipline imposed over the process of software architecture and implementation in aviation (moreso than medical devices, it would seem) is both inspiring and instructive, and I definitely look up to it.
I must admit I'm genuinely interested to learn more about how the role of UI design plays into avionics construction - I've leaned toward UX for quite a while (I think I started headscratching about the subject around 13-14, although I didn't know that was what it was called at the time) and I think it's probably something I'd do pretty well at when I'm finally looking for a job. Web UX is... frustrating and demotivating, though. I don't want to kill myself doing that.
I really like the UI design that goes into avionics - the fact that every possible scenario has to be thought out and handled, and that the end result has no flashy eyecandy or extraneous functionality; it's all function, it's all required (or it's not there); everything on the screen at any given time is significant, and (hopefully) care is taken that the amount of data (ie, significance) showing at any one moment is not information overload. A very hard balance to get right, I'm sure.
The rigor and discipline imposed over the process of software architecture and implementation in aviation (moreso than medical devices, it would seem) is both inspiring and instructive, and I definitely look up to it.
I must admit I'm genuinely interested to learn more about how the role of UI design plays into avionics construction - I've leaned toward UX for quite a while (I think I started headscratching about the subject around 13-14, although I didn't know that was what it was called at the time) and I think it's probably something I'd do pretty well at when I'm finally looking for a job. Web UX is... frustrating and demotivating, though. I don't want to kill myself doing that.
There's much more than avionics if you navigate up the path:
https://spaceflight.nasa.gov/shuttle/reference/
https://spaceflight.nasa.gov/shuttle/reference/
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But it has no pictures! And the font is so tiny :( my eyes can read it, but my brain's getting scared by the walls of text.
What I'd love to see is photos of the various modules, and then further photos of all the insides.
--
Probably the thing I want the most - as crazy as this probably sounds - is a character ROM dump. I like fonts from old things :/
I recently learned that the bit of avionics with the weird keyboard in it that's typically found in "large" aircraft is called a Control Display Unit, or CDU. (Here's a random 747 cockpit with two shown facing upwards: http://flic.kr/p/aFRHt4). I did an image search for CDU font, and promptly had one of those times I immediately hit the jackpot: http://sigmatechnica.com/lynx-helecopter-cdu-semi-teardown/ has a 2048x1536 photo of someone who randomly got a CDU from a Lynx helicopter off eBay to poke at, and took a bunch of photos of everything they could make it do, including the font-self test!
That's the kind of thing I wish I had, but for random industrial equipment - and, sure, the space shuttle. (Know where I can find ROMs for old avionics? lol)
For the VT220 font-rendering geeks, the CRT in the mentioned CDU (no model info :( ) happens to be mounted vertically.