Reverse-engineering the electronics in the Globus analog navigational computer | Hacker News Reader

Reverse-engineering the electronics in the Globus analog navigational computer

righto.com

158 pointsrcarmo26 comments

I hope someone makes a replica, including the rolling physical globe (though maybe with an Arduino or RasPi in place of some of the clockwork).

Or maybe it inspires other uses of a rolling physical globe. For example, a steampunk "global video meeting" device (Zoom/Jitsi/etc. client), including globe that animates to show participants. Vintage round B&W CRTs to display them, old-timey radio audio distortion, optional transatlantic accent filters, brass and gauges, etc. Maybe for a novelty in an office common area, kids' technology museum, or somewhere. If it was reproducible open source designs, the devices could talk to each other, such as between two museums, maybe to shake up the familiarity of modern video communications and remind what a wonder it is that we can interact around the world casually.

To simplify it down to being 3D printed and driven/positioned by a computer should indeed be straightforward. It looks like a lot of the mechanical complexity is there for lack of a digital computer.

A couple of servos, one to roll, one to pitch the ball and then a lot of quaternion math on the Pi should get you there.

The clever thing about the globe is that it doesn't do arbitrary rotations, so the mechanical connections are simplified. Instead, it has two degrees of freedom through two fixed, co-axial shafts.

Specifically, the globe rotates at an angle of 51.8°, corresponding to the launch angle of the spacecraft. Spinning the globe at this angle gives you the orbital track without any real computation. The other rotation is the Earth around its axis. The trick here is that the equator is a fixed frame, while the two hemispheres are rotated based on the input shaft.

Ken Shirriff is just awesome. He regularly posts on Mastodon¹ about his reverse engineering endeavors of old x86 chips.

[1] https://mastodon.social/@kenshirriff@oldbytes.space

Thanks! I primarily post on Twitter as @kenshirriff but also post on Mastodon.

Everyone here watches Curious Marc on YouTube, right?

If not, here are part 1 and 2 of opening up and repairing the thing:

- https://www.youtube.com/watch?v=dmHaCQ8Ul6E

- https://www.youtube.com/watch?v=CP5dfjxdkQ4

And a 47 second time-lapse video of the Globus doing 7 orbits:

- https://www.youtube.com/watch?v=nDHtJy9cpC0

(there is an earlier time lapse video as well, linked in the blog post)

And, of course, his and his friends' amazing Apollo Guidance Computer restoration series: https://www.youtube.com/playlist?list=PL-_93BVApb59FWrLZfdli...

If you follow the channel you know all about Master Ken.

What a beautiful device! If I had one I would struggle between wanting to preserve it untouched and repurposing it with mechanical and electronics implants as a display to see where a given space object is; imagine watching it track the ISS in real time. Preserving it would probably win, but now I'll hardly resist the temptation to buy the first globe I see at the next pawn shop...

In fact, try to find a second if you can, it will resolve your first dilemma (or it would for me, ha ha).

This thing is just amazingly cool and clever. I am curious if this was a critical piece of capsule instrumentation or more of an onboard backup? I have no idea how Russian space missions are run so it’s not clear to me how much is done at their equivalent of ground control vs. what is done on board.

In particular I am wondering about that landing mode.

It is custom made for each spacecraft, since it can only rotate on the planned flight path. I think it's a good guide for the astronaut where they are in the globe and the globe also have markers of communication tower they can contact.

At least on the early Soviet space missions, the cosmonauts had almost no control by default and most of the control was by onboard sequencing. The controls were actually locked with a combination lock. The Globus was more of a backup. The landing mode feature wasn't added until 1967.

Based on the book "Beyond" (Walker) about the early Soviet space program and Yuri Gagarin. A very interesting book and I recommend it.

I love seeing teardowns of old space tech. Having worked on safety critical projects I know that if something is proven and works it is generally not replaced unless something substantially better comes along, so I wonder if the soyuz still flies with these electromechanical wonders.

I think the Soyuz-TMA spacecraft (2002) upgraded to the Neptun-ME system, which has digital displays rather than the Globus.

П217 germanium transistors - I remember them. They were a top at the П213-П217 range, normally you would be lucky to get hold of 213 or 214. Used them on the last stage of my first audio amplifier.

An interesting thing about these transistors is they look like standard power transistors in a metal TO-3 package. However, the transistor itself is in a round metal package, and the metal flange is separate, and holds down the transistor. Soviet electronics is like an alternate universe where things are similar but also unexpectedly different. (Vintage IBM electronics has the same feel.)

Ironically, this page is blocked in Russia...

It is not blocked for me. I am in Russia.

403

К сожалению, доступ к странице ограничен.

Хм, проверил еще раз. Все равно работает. Может быть временная блокировка со стороны Cloudflare?

Really cool, I have often wondered about the "maps" in the Russian helicopter cockpits.

I think they also move depending on the heading and direction of the helicopter to show the relative position for navigation.

Would be interesting to see how they worked.

Pic of cockpit - https://www.alamy.com/dashboard-in-a-russian-soviet-helicopt...

Does someone open access mirror? Blocked for me.

https://web.archive.org/web/20230306135640/http://www.righto...

Thank you!

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