Listening To The Sounds Of An 1960s Military Computer

Restoring vintage computers is the favorite task of many hardware hackers. Retrocomputing probably makes you think of home computer brands like Commodore, Amiga, or Apple but [Erik Baigar] is deeply into collecting early military computers from the UK-based Elliott company. Earlier this year he made a detailed video that shows how he successfully brought an Elliott 920M from the 1960s back to life.

It is quite amazing that the Elliott company already managed to fit their 1960s computer into a shoebox-sized footprint. As computers had not yet settled on the common 8bit word size back then the Elliott 900 series are rather exotic 18bit or 12bit machines. The 920M was used as a guidance computer for European space rockets in the 1960s and ’70s but also for navigational purposes in fighter jets until as late as 2010.

Opening up the innards of this machine reveals some exotic quirks of early electronics manufacturing. The logic modules contain multilayer PCBs where components were welded instead of soldered onto thin sheets of mylar foil that were then potted in Araldite.

To get the computer running [Erik Baigar] first had to recreate the custom connectors using a milling machine. He then used an Arduino to simulate a paper tape reader and load programs into the machine. An interesting hack is when he makes the memory reading and writing audible by simply placing a radio next to the machine. [Erik Baigar] finishes off his demonstration of the computer by running some classic BASIC games like tic-tac-toe and a maze creator.

If you would like to code your own BASIC programs on more modern hardware you should check out this BASIC interpreter for the Raspberry Pi Pico.

Video after the break.

Continue reading “Listening To The Sounds Of An 1960s Military Computer”

So How Does A Rocket Fly Sideways, Anyway?

It’s often said that getting into orbit is less about going up, and more about going sideways very fast. So in that sense, the recent launch conducted by aerospace startup Astra could be seen as the vehicle simply getting the order of operations wrong. Instead of going up and then burning towards the horizon, it made an exceptionally unusual sideways flight before finally moving skyward.

As you might expect, the booster didn’t make it to orbit. But not for lack of trying. In fact, that the 11.6 meter (38 feet) vehicle was able to navigate through its unprecedented lateral maneuver and largely correct its flight-path is a testament to the engineering prowess of the team at the Alameda, California based company. It’s worth noting that it was the ground controller’s decision to cut the rocket’s engines once it had flown high and far enough away to not endanger anyone on the ground that ultimately ended the flight; the booster itself was still fighting to reach space until the very last moment.

Astra’s rocket on the launch pad.

There’s a certain irony to the fact that this flight, the third Astra has attempted since their founding in 2016, was the first to be live streamed to YouTube. Had the company not pulled back their usual veil of secrecy, we likely wouldn’t have such glorious high-resolution footage of what will forever be remembered as one of the most bizarre rocket mishaps in history. The surreal image of the rocket smoothly sliding out of frame as if it was trying to avoid the camera’s gaze has already become a meme online, arguably reaching a larger and more diverse audience than would have resulted from a successful launch. As they say, there’s no such thing as bad press.

Naturally, the viral clip has spurred some questions. You don’t have to be a space expert to know that the pointy end of the rocket is usually supposed to go up, but considering how smooth the maneuver looks, some have even wondered if it wasn’t somehow intentional. With so much attention on this unusual event, it seems like the perfect time to take a close look at how Astra’s latest rocket launch went, quite literally, sideways.

Continue reading “So How Does A Rocket Fly Sideways, Anyway?”

Up Close And Personal With Some Busted Avionics

When he found this broken Narco DME 890 that was headed for the trash, [Yeo Kheng Meng] did what any self-respecting hardware hacker would do: he took it back to his workbench so he could crack it open. After all, it’s not often you get to look at a piece of tech built to the exacting standards required by even outdated avionics.

DME stands for “Distance Measuring Equipment”, and as you might expect from the name, it indicates how far the aircraft is from a given target. [Yeo Kheng Meng] actually goes pretty deep into the theory behind how it works in his write-up if you’re interested in the nuts and bolts of it all, but the short version is that the pilot selects the frequency of a known station on the ground, and the distance to the target is displayed on the screen.

Inside the device, [Yeo Kheng Meng] found several densely packed boards, each isolated to minimize interference. The main PCB plays host to the Mostek MK3870 microcontroller, an 8-bit chip that screams along at 4 MHz and offers a spacious 128 bytes of RAM. It doesn’t sound like much to the modern AVR wrangler, but for 1977, it was cutting edge stuff.

Digging further, [Yeo Kheng Meng] opens up the metal cans that hold the transmitter and receiver. Thanks to the excellent documentation available for the device, which contains extensive schematics and block diagrams, he was able to ascertain the function of many of the components. Even if you’re unlikely to ever go hands on with this type of technology, it’s fascinating to see the thought and attention to detail that goes into even seemingly mundane aspects of the hardware.

Hungry for more airworthy engineering? We’ve taken a close look at some hardware pulled from a civilian airliner, as well as some battle-hardened electronics that once graced the cockpit of an AH-64 Apache attack helicopter.

Aircraft Compass Teardown

We didn’t know what a C-2400 LP was before we saw [David’s] video below, but it turned out to be pretty interesting. The device is an aircraft compass and after replacing it, he decided to take it apart for us. Turns out, that like a nautical compass, these devices need adjustment for all the metal around them. But while a ship’s compass has huge steel balls for that purpose, the tiny and lightweight aviation compass has to be a bit more parsimonious.

The little device that stands in for a binnacle’s compensators — often called Kelvin’s balls — is almost like a mechanical watch. Tiny gears and ratchets, all in brass. Apparently, the device is pretty reliable since the date on this one is 1966.

Continue reading “Aircraft Compass Teardown”

Exploring Turn Of The Century RAF Avionics

The second hand market is a wonderful thing; you never know what you might find selling for pennies on the dollar simply because it’s a few years behind the curve. You might even be able to scrounge up some electronics pulled out of a military aircraft during its last refit. That seems to be how [Adrian Smith] got his hands on a Control Display Unit (CDU) originally installed in a Royal Air Force AgustaWestland AW101 “Merlin” helicopter. Not content to just toss it up on a shelf, he decided to take a look inside of the heavy-duty cockpit module and see if he couldn’t make some sense out of how it works.

Unsurprisingly, [Adrian] wasn’t able to find much information on this device on the public Internet. The military are kind of funny like that. But a close look at the burn-in on the CDU’s orange-on-black plasma display seems to indicate it had something to do with the helicopter’s communication systems. Interestingly, even if the device isn’t strictly functional when outside of the aircraft, it does have a pretty comprehensive self-test and diagnostic system on-board. As you can see in the video after the break, there were several menus and test functions he was able to mess around with once it was powered up on the bench.

With the case cracked open, [Adrian] found three separate PCBs in addition to the display and keyboard panel on the face of the CDU. The first board is likely responsible for communicating with the helicopter’s internal systems, as it features a MIL-STD-1553B interface module, UART chips, and several RS-232/RS-485 transceivers. The second PCB has a 32-bit AMD microcontroller and appears to serve as the keyboard and display controller, possibly also providing the on-board user interface. The last board looks to be the brains of the operation, with a 25 MHz Motorola 68EC020 CPU and 1Mb of flash.

All of the hardware inside the CDU is pretty generic, but that’s probably the point. [Adrian] theorizes that the device serves as something of a generic pilot interface module, and when installed in the Merlin, could take on various functions based on whatever software was loaded onto it. He’s found pictures online that seem to show as many as three identical CDUs in the cockpit, all presumably running a different system.

[Adrian] has uncovered some interesting diagnostic information being dumped to the CDU’s rear connectors, but he’s still a long way off from actually putting the device to any sort of practical use. If any Hackaday readers have some inside information on this sort of hardware, we’re sure like to hear about it.

Continue reading “Exploring Turn Of The Century RAF Avionics”

Fighter Jet’s Gyro Stays Upright Before It Self-Destructs

Aviation instruments are highly interesting pieces of engineering, and it is quite satisfying to watch the often over-engineered mechanisms behind them. If you are into that sort of thing it is worthwhile to check out [Erik Baigar]’s video where he explains the working principle of the attitude indicator from a Tornado jet.

The attitude indicator or artificial horizon of an airplane is one of the most important instruments, especially during poor sight. The ADI42-124 used in the Tornado jet is completely standalone and only needs a DC power supply which is why [Erik Baigar] can show it off while standing on his balcony. At the heart of this instrument is a gyroscope which consists of a spinning disc attached to a gimbal mount. Due to the conservation of angular momentum, the spin axis will always keep its orientation when the instrument is rotated. However, mechanical gyroscopes tend to drift over time and therefore include a mechanism to keep the spin axis upright with respect to the direction of gravity. The ADI42-124 uses an entirely mechanical mechanism for this based on free swiveling weights. Forget everything we said earlier about overengineering as [Erik Baigar] also uncovers a fatal design flaw which leads to the instrument’s self-destruction as shown in the picture here. Unfortunately, this will render most of the units you can buy on eBay useless.

Be sure to check out [Erik Baigar]’s webpage which is nerd paradise for vintage computer and avionics fans or watch another gyroscope teardown.

Video after the break.

Continue reading “Fighter Jet’s Gyro Stays Upright Before It Self-Destructs”

If You Are Planning On Building Your Own Space Shuttle…

One of the most complicated machines ever built was the US space shuttle (technically, the STS or Space Transportation System). Despite the title, we doubt anyone is going to duplicate it. However, one of the most interesting things about the shuttle’s avionics — the electronics that operate the machine — is that being a government project there is a ridiculous amount of material available about how it works. NASA has a page that gathers up a description of the vehicle’s avionics. If you are more interested in the actual rocket science, just back up a few levels.

We will warn you, though, that if you’ve never worked on space hardware, some of the design choices will seem strange. There are two reasons for that. First, the environment is very strange. You have to deal with high acceleration, shock, vibration, and radiation, among other things. The other reason is that the amount of time between design and deployment is so long due to testing and just plain red tape that you will almost certainly be deploying with technology that is nearly out of date if not obsolete.

Continue reading “If You Are Planning On Building Your Own Space Shuttle…”