6 ms·

I'm struggling to wrap my head around manufacturing so many parts to the needed tolerances and having them work under the temperature swings and forces seen in

I'm struggling to wrap my head around manufacturing so many parts to the needed tolerances and having them work under the temperature swings and forces seen in flight. Debugging these analog computers would involve a large number of engineering disciplines! Impressive technology and excellent article.

Animats 3y ago
It's not that hard. All the components here are common and well-behaved - gears, cams, bearings, shafts, mounting plates, and synchros. Only the mounting plates, shafts, and cams are fully custom. Everything else is an off the shelf part. It's like designing electronics - you use standard components, but boards are custom for the job. Design is mostly topology plus constraints to make it fit and keep vibration and backlash under control. There are mechanical equivalents to proto boards, sort of like Lego gearing, but all metal. W.M. Berg used to be the main US maker. So you make up all the functionality on a breadboard, test with inputs and outputs, then rearrange for production. The mechanical design is like medium duty clockmaking. Teletype machines are in roughly the same scale - the parts can be handled without tweezers and are not too fragile. (And all custom, with far more levers than gears.) It's possible to go smaller but everything becomes more fragile and wears faster. It's roughly the same technology as naval fire direction computers [1], but smaller and more automated. [1] https://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer https://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer
- OldGuyInTheClub 3y ago
  When I was in basic research I thought that concept development and prototyping represented the hard part of the work, requiring actual brain power. Show it works and the rest is "engineering." Then, I moved to industry where products have to meet size, weight, and power restrictions, be manufacturable, testable, deployable, and usable by people who have other things to do. Aircraft usually come down so add serviceability. For most space applications, it's even more stressing. Even within engineering disciplines there's a tendency to "throw the design over the wall to manufacturing." It usually leads to bad news. The transition from TRL(Technology Readiness Level) 4 to TRL 7 in NASA's parlance is called the "Valley of Death" for good reason. https://mkainsights.com/insights/fundamentals-operations/trl/ https://mkainsights.com/insights/fundamentals-operations/trl...
- eternityforest 3y ago
  One big difference is that it's all in 3D. Electronics is done with off the shelf parts, physical position doesn't usually matter to the millimeter, electricity follows the wire except with RF and high voltage. The other difference is that none of the techniques are familiar to anyone but MEs anymore. Most hackers know software, some of us can do hardware, a few can do light woodworking and 3D printing... but I've never implemented even basic logic in any mechanical way. Plus, they had to do it all WITHOUT CAD. Everything about it is impressive and really cool.
  - Animats 3y ago
    > The other difference is that none of the techniques are familiar to anyone but MEs anymore. There is that. But this thing isn't that bad. All the motion is slow. There are no gyros. The precision requirements are modest. It's only 2 1/2D; it's a vertical component stack. There are no diagonal shafts or long, odd-shaped levers. It's not power-limited to the degree that a clock is. Everything is statically driven; there are no components that depend on inertia, which is appropriate for an aircraft system. It doesn't have wheel and disc integrators, which depend on friction and are touchy. This thing is all gears and cams, which are well-behaved. As the original article points out, it performs a simple computation which is a well defined function of the current inputs. I've seen the ground-based mechanical computers that controlled a Nike missile, and those are similar technology as this but much more complex. I've restored century-old Teletype machines, and those are more complex than this thing. Now, those really did require mechanical genius to design. All the good Teletype machines were designed by two people, Howard Krum and Ed Klienschmidt. It took a long time, decades, to get the core design right, and even Siemens, which built their own variation, did not redesign the core decoding mechanism. William Burroughs designed the first really reliable adding machine mechanism, and Burroughs dominated that market for decades. Burroughs had to design by scribing lines on zinc sheets; paper drawings didn't hold dimensions accurately enough. Ottmar Mergenthaler's Linotype design barely changed over a century, being better than both its predecessors and successors. Those guys were mechanical design geniuses. This Bendix device is a good, workmanlike design, but not in that class.
    - eternityforest 3y ago
fumeux_fume 3y ago
It's impressive what the USA was capable of manufacturing from the 1940s to the 60s. My Bendix 6080 vacuum tubes were rated for use in missiles and can withstand very extreme conditions. Overkill for my application, but ensures years of reliable use in my headphone amp!
- OldGuyInTheClub 3y ago
  Agreed. I never thought much about fuzes but Curious Droid's video on the proximity fuze used during WW2 was eye-opening. Vacuum tubes surviving launch in an artillery shell... https://www.youtube.com/watch?v=N0SgC78YFPc https://www.youtube.com/watch?v=N0SgC78YFPc
edrxty 3y ago
I feel like the designers of this would feel the same way about the current solution involving sand that has been imbued with the ability to think. We take for granted the abstractions and mental models/tools we have to manage the complexity of the current paradigm. No doubt, the engineers who created this had their own structures for understanding the complexity at work here.
- eternityforest 3y ago
  It's almost like a foreign language! I was just in another discussion the other day about how I rarely use pen and paper, and how that affects my thoughts since my "native language" for thinking about the world is "stuff that can be said on a phone call, typed on a keyboard, or made with CAD primitives". Back in the day when everything started on paper there might have been a bigger variety of abstractions, because people were starting with a literal blank canvas and making their own tools to implement their ideas rather than most people largely just exploring the possibilities that naturally fit existing tools. Stuff is way easier now and overall tech is so much better, but I wonder if part of the cool factor people feel about old stuff is from the lack of constraint.
userbinator 3y ago
It's worth noting that when this was designed, mechanical clocks and watches, which work on similar principles, were already a few centuries old, as were various types of mechanical calculators. Moreover, I'd say that "debugging" one of these is actually easier in many ways than software --- everything can be inspected directly and manipulated.

Animats 3y ago

It's not that hard. All the components here are common and well-behaved - gears, cams, bearings, shafts, mounting plates, and synchros. Only the mounting plates, shafts, and cams are fully custom. Everything else is an off the shelf part. It's like designing electronics - you use standard components, but boards are custom for the job. Design is mostly topology plus constraints to make it fit and keep vibration and backlash under control. There are mechanical equivalents to proto boards, sort of like Lego gearing, but all metal. W.M. Berg used to be the main US maker. So you make up all the functionality on a breadboard, test with inputs and outputs, then rearrange for production. The mechanical design is like medium duty clockmaking. Teletype machines are in roughly the same scale - the parts can be handled without tweezers and are not too fragile. (And all custom, with far more levers than gears.) It's possible to go smaller but everything becomes more fragile and wears faster. It's roughly the same technology as naval fire direction computers [1], but smaller and more automated. [1] https://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer https://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer

OldGuyInTheClub 3y ago
When I was in basic research I thought that concept development and prototyping represented the hard part of the work, requiring actual brain power. Show it works and the rest is "engineering." Then, I moved to industry where products have to meet size, weight, and power restrictions, be manufacturable, testable, deployable, and usable by people who have other things to do. Aircraft usually come down so add serviceability. For most space applications, it's even more stressing. Even within engineering disciplines there's a tendency to "throw the design over the wall to manufacturing." It usually leads to bad news. The transition from TRL(Technology Readiness Level) 4 to TRL 7 in NASA's parlance is called the "Valley of Death" for good reason. https://mkainsights.com/insights/fundamentals-operations/trl/ https://mkainsights.com/insights/fundamentals-operations/trl...
eternityforest 3y ago
One big difference is that it's all in 3D. Electronics is done with off the shelf parts, physical position doesn't usually matter to the millimeter, electricity follows the wire except with RF and high voltage. The other difference is that none of the techniques are familiar to anyone but MEs anymore. Most hackers know software, some of us can do hardware, a few can do light woodworking and 3D printing... but I've never implemented even basic logic in any mechanical way. Plus, they had to do it all WITHOUT CAD. Everything about it is impressive and really cool.
- Animats 3y ago
  > The other difference is that none of the techniques are familiar to anyone but MEs anymore. There is that. But this thing isn't that bad. All the motion is slow. There are no gyros. The precision requirements are modest. It's only 2 1/2D; it's a vertical component stack. There are no diagonal shafts or long, odd-shaped levers. It's not power-limited to the degree that a clock is. Everything is statically driven; there are no components that depend on inertia, which is appropriate for an aircraft system. It doesn't have wheel and disc integrators, which depend on friction and are touchy. This thing is all gears and cams, which are well-behaved. As the original article points out, it performs a simple computation which is a well defined function of the current inputs. I've seen the ground-based mechanical computers that controlled a Nike missile, and those are similar technology as this but much more complex. I've restored century-old Teletype machines, and those are more complex than this thing. Now, those really did require mechanical genius to design. All the good Teletype machines were designed by two people, Howard Krum and Ed Klienschmidt. It took a long time, decades, to get the core design right, and even Siemens, which built their own variation, did not redesign the core decoding mechanism. William Burroughs designed the first really reliable adding machine mechanism, and Burroughs dominated that market for decades. Burroughs had to design by scribing lines on zinc sheets; paper drawings didn't hold dimensions accurately enough. Ottmar Mergenthaler's Linotype design barely changed over a century, being better than both its predecessors and successors. Those guys were mechanical design geniuses. This Bendix device is a good, workmanlike design, but not in that class.
  - eternityforest 3y ago

fumeux_fume 3y ago

It's impressive what the USA was capable of manufacturing from the 1940s to the 60s. My Bendix 6080 vacuum tubes were rated for use in missiles and can withstand very extreme conditions. Overkill for my application, but ensures years of reliable use in my headphone amp!

OldGuyInTheClub 3y ago
Agreed. I never thought much about fuzes but Curious Droid's video on the proximity fuze used during WW2 was eye-opening. Vacuum tubes surviving launch in an artillery shell... https://www.youtube.com/watch?v=N0SgC78YFPc https://www.youtube.com/watch?v=N0SgC78YFPc

edrxty 3y ago

I feel like the designers of this would feel the same way about the current solution involving sand that has been imbued with the ability to think. We take for granted the abstractions and mental models/tools we have to manage the complexity of the current paradigm. No doubt, the engineers who created this had their own structures for understanding the complexity at work here.

eternityforest 3y ago
It's almost like a foreign language! I was just in another discussion the other day about how I rarely use pen and paper, and how that affects my thoughts since my "native language" for thinking about the world is "stuff that can be said on a phone call, typed on a keyboard, or made with CAD primitives". Back in the day when everything started on paper there might have been a bigger variety of abstractions, because people were starting with a literal blank canvas and making their own tools to implement their ideas rather than most people largely just exploring the possibilities that naturally fit existing tools. Stuff is way easier now and overall tech is so much better, but I wonder if part of the cool factor people feel about old stuff is from the lack of constraint.

userbinator 3y ago

It's worth noting that when this was designed, mechanical clocks and watches, which work on similar principles, were already a few centuries old, as were various types of mechanical calculators. Moreover, I'd say that "debugging" one of these is actually easier in many ways than software --- everything can be inspected directly and manipulated.