Reverse-engineering a three-axis attitude indicator from the F-4 fighter plane
righto.com
righto.com
And it amazes me how many analog tricks they used. Modern day would be a couple lines of code.
In 1954, Rex Rice wrote this piece about preferring a simple plugboard as the means of programming a computer, versus any sort of abstraction with a programming language (https://dl.acm.org/doi/10.1145/1455270.1455272). So it was still very much up for debate, whether high-level programming languages were even the right solution for the problems being faced.
But I agree with you, our forefathers were simply geniuses to have figured out how to manipulate the physical world to produce mathematical computations. Early in his career, my dad had to disassemble and reverse-engineer some Soviet-made aerospace devices, and he still fondly recalls how superbly engineered and precise the Soviet devices were. I wish there was more information out there about Soviet computing, but the winners do write history after all.
But then you look at it and think Yeah, obviously they're not going to have MTBF times in the millions. It's going to be hundreds of hours - once a week, or maybe every few weeks between real hard crashes.
How would that change your behaviour.
This is why I have my doubts about existing designs for quantum computers, the quantum algorithms we are trying to solve in hardware require an analog design and we rejected analog computers before, mainly because they were unable to scale. This inability to scale is the same problem we see with quantum computers.
This is a huge departure from the physical world, and it speaks to what a massive benefit computers bring.
Impossible to know, though the use of nuclear weapons by an enemy was probably on everyone's mind, and diversity of redundant systems may have been applied in case some hypothetical enemy air defense came about during the lifespan of the aircraft.
(Only pondering though, I have had the same idle thoughts about making my own Russian Soyuz mechanical navigation instrument too from this other writeup of Ken's https://www.righto.com/2023/01/inside-globus-ink-mechanical-... but somehow the idea of making replica soviet vintage tech isn't as appealing as it was a few years back...)
The number of planes without a vacuum system but with electrical mechanical attitude indicators is quite small. Your best bet are electric mechanical backup instruments used on earlier installations of the all-glass G1000.
Take a look at Diamond DA40 and DA42 for electrical backup attitude indicators, but for example their next models (DA50 and DA62) use all-glass backup instruments.
I'm not sure how accurate the magnetometers are, and how accurate the calculated compass heading can be, but I recall a project where I used a pair 6DOF accelerometer/magnetometer breakout boards to measure the angle change between the body and the grind setting adjustment ring to datalog my coffee grinder, and I was getting 10bit resolution degrees which all _seemed_ to accurately track the small sub 1 degree adjustments when dialing in the grind. Although I'll admit to not taking the time to understand all the math involved to get from the raw 3 axis acceleration and microTesla magnetic measurements to compass heading, I just copy/pasted sample Arduino code which gave me 1 decimal place degrees. But my grinder has 100 "notches" around the 360 degrees of the grind adjustment ring, and my data logger at least looked like it was accurately/repeatably showing changes down in the quarter to half a notch range.
So while I don't think $50 worth of stuff from Adafruit will get you <0.01deg/hour gyro drift rate, with magnetic calibrations and sensor fusion you could probably hit at least 0.1deg long term precision/accuracy, so over 10 or more hours you'd have "navigation grade" accuracy. Which is probably "good enough" for anything traveling at less that a couple of hundred MPH. 0.1deg error is about 1km every 600km - so if you were sailing from Sydney to San Francisco (with no GPS or astro nav equipment) which is ~12,000km, you'd be within 20km or so when you got there. Which seems "close enough" for anything except delivering nukes.
Sure, the F-35 is a multirole fighter aircraft with a gun - so is the F-15E, but that doesn't make it a dogfighter. If you're in a position where a guns solution is your only kill option in an F-15 or an F-35, something has gone terribly wrong. Pretty much everything about both jets is designed to operate in a theater with extremely high levels of air support and friendly materiel. It is assumed that they won't get into a dogfight because it is extraordinarily rare for an F-35 to exhaust two AIM-120s in a single sortie, let alone the 6 it can carry in stealth mode or the whopping 12 AMRAAMs that the F-15 can lug along.
Even as far back as the Vietnam War, forcing a missile truck like the F-4 into a dogfight with a MiG-15 was a death sentence. You don't need a very active imagination to suppose how an F-35 fares in a guns-only dogfight against an Su-27.
Also, you are not carrying that many MRMs on an eagle unless it's the new one with quad packs.
EDIT: I believe I've also seen F22s but I have no idea where they're from.
In old gun fights (which just don't happen anymore), shots were likely to come from behind (so, they intersect the pilot) or the top (so, through the canopy if they're hitting the instruments). This has to do with the orientation both planes are probably in if one is shooting at the other. Go back farther and you get shots from the front, not from fighters (head-ons are very difficult to pull off outside of videogames) but from bomber tail gunners - very old planes from WWII even had bulletproof glass in front of the pilot for this reason. If the F35 has gotten into a gunfight, the pilot has fucked up, it's not a dogfighter and wasn't designed to be one.
Even nowadays, if the missile or flak pops next to the cockpit and has managed to damage the instruments, there is a very strong chance the shrapnel has also hurt the pilot to the point that they're not flying home that day. This is the most likely way for the F-35 to be damaged in the modern era.
There are obviously scenarios where the instrument panel gets damaged but the pilot is okay, but it's such a low probability scenario that they likely deemed it to be less harmful than the benefit they foresee in a glass cockpit.
Presumably that also would be duplicated. Why go to all the effort of having two displays but still have the risk of a single backlight going out and making both displays useless?
I have never really thought much about it, but I guess the actual LCD thingie is manufactured in one piece and the control signals just being split between different computers somehow, but I don't know anything about how these things are made! :)
There are companies that make displays that have clear conductors over the screen so they can heat them so they can be used and maintain function even when on the deck of an aircraft carrier in the arctic.
There are companies that still make CRTs for specific military purposes.
These screens are safer, more reliable, and durable than the mechanical systems they replace.
[1] https://www.collinsaerospace.com/what-we-do/industries/milit...
Wait, you're the Linux/4004 guy, aren't you? That project was truly amazing.
His “lab” was basically all about testing and simulating environments for the instruments. He had tons of sayings about not having room for error in his line of work. This is as close as you can get from “building bridges” and to this day I don’t think I have seen this level of attention to detail/perfection in any other profession.
His job involved electronical engineering , mechanical engineering and programming amongst other things, not to mention a deep knowledge of the physics of these environments.
Back then also the tools or source of information that were available to them were quite crude compared to what we have now.
His spare time was all about flying, pimping his ham radio gear with all kind of “home made” electronics, build antennas and messing with computers. I guess he’d qualify as a “Hacker” nowadays.
Also, I've never been at a place that tested FW patches as well as full releases, so...do you _really_ want to install somebody else's random FW patch? I don't unless I have some known problem with a fix in the release notes...