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.

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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.

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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.

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Build Your Own Avionics Suite, If You Dare

If you’re really interested in aircraft and flying, there are many ways to explore that interest. There are models of a wide range of sizes and complexities that are powered and remote-controlled, and even some small lightweight aircraft that can get you airborne yourself for a minimum of expense. If you’re lucky enough to have your own proper airplane, though, and you’re really into open source projects, you can also replace your airplane’s avionics kit with your own open source one.

Avionics are the electronics that control and monitor the aircraft, and they’re a significant part of the aircraft’s ability to fly properly. This avionics package from [j-omega] (who can also be found on hackaday.io) will fit onto a small aircraft engine and monitor things like oil temperature, RPM, coolant temperature, and a wide array of other features of the engine. It’s based on an ATmega microcontroller, and has open-source schematics for the entire project and instructions for building it yourself. Right now it doesn’t seem like the firmware is available on the GitHub page yet, but will hopefully be posted soon for anyone who’s interested in an open-source avionics package like this.

The project page does mention that this is experimental as well, so it might not be advised to use in your own personal aircraft without some proper testing first. That being said, if you’ve heard that warning and have decided just to stay on the ground, it’s possible to have a great experience without getting in a real airplane at all.

Open Source Modular Rocket Avionics Package

Cambridge postgraduate student [Adam Greig] helped design a rocket avionics system consisting of a series of disc-shaped PCBs arranged in a stack. There’s a lot that went into the system and you can get a good look at it all through the flickr album.

Built with the help of Cambridge University Spaceflight, the Martlet is a 3-staging sounding rocket that lifts to 15km/50K feet on Cesaroni Pro98 engines. [Adam]’s control system uses several Arm Cortex M4s on various boards rather than having just one brain controlling everything.

Each disc is a module that plays a specific role in the system. There are a couple of power supply boards sporting twin LTC2975 able to supply custom power to a dozen different circuits. The power system has a master control board also sporting an M4. There’s an IMU board with the guidance system — accelerometer, magnetometer, gyroscope, and barometer, all monitored by an algorithm that computes the rocket’s position and attitude in-flight. There’s a radio board with a GPS receiver and an ISM band radio transceiver for telemetry, as well as a datalogger with 10 thermocouple measurement channels. Engines are controlled by the pyro board which controls firing currents on four different channels. The vertical spacers also serve to transmit power and data to neighboring boards.

If you’re interested in learning more, check out the project’s code and schematics on [Adam]’s GitHub repository.

[Adam] is no stranger to these pages, with his Nerf Vulcan turret published a few years back, as well as his balloon tracking rig published more recently. Photos are CC-SA and can be found in [Adam]’s Flickr feed.

A Next-Level Home-Built Flight Simulator

Every hobby needs to have a few people who take it just a little too far. In particular, the aviation hobbies – Radio control flying, FPV multicopter racing, and the like – seem to inspire more than their fair share of hard-core builds. In witness whereof we present this over-the-top home-brew flight simulator.

His wife and friends think he’s crazy, and we agree. But [XPilotSimPro] is that special kind of crazy that it takes to advance the state of the art, and we applaud him for that. A long-time fan of flight simulator games, he was lucky enough to log some time in a real 737 simulator. That seems to be where he caught the DIY bug. The video after the break is a whirlwind tour of the main part of his build, which does not seek to faithfully reproduce any particular cockpit as much as create a plausibly awesome one. Built on a PVC pipe frame with plywood panels, the cockpit is bristling with LCD panels, flight instruments, and bays of avionics that look like they came out of a cockpit. The simulator sits facing a wall with an overhead LCD projector providing views of the outside world. An overhead panel sporting yet more LCD panels and instruments was a recent addition. The whole thing is powered by a hefty looking gaming rig running X-Plane, allowing [XPilotSimPro] to take on any aviation challenge, including landing an Embraer 109 on the deck of the USS Nimitz Aircraft Carrier.

What could be next for [XPilotSimPro]’s simulator? How about adding a little motion control with pneumatics? Or better still, how about using a real 737 cockpit as a simulator?

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Hackaday Links: May 24, 2015

A few months ago, we heard about a random guy finding injection molds for old Commodore computers. He did what the best of us would do and started a Kickstarter to remanufacture these cool old cases. It’s the best story on retrocomputing this year, and someone else figured out they could remanufacture Commodore 64 keycaps. If you got one of these remanufactured cases, give the keycaps a look.

Remember this Android app that will tell you the value of resistors by reading their color code. Another option for the iOS crowd was presented at Maker Faire last weekend. It’s called ResistorVision, and it’s perfect for the colorblind people out there. An Android version of ResistorVision will be released sometime in the near future.

A few folks at Langly Research Center have a very cool job. They built a hybrid electric tilt wing plane with eight motors on the wing and two on the tail. It’s ultimately powered by two 8 hp diesel engines that charge Liion batteries. When it comes to hydrocarbon-powered hovering behemoths, our heart is with Goliath.

A bottom-of-the-line avionics panel for a small private plane costs about $10,000. How do you reduce the cost? Getting rid of FAA certification? Yeah. And by putting a Raspberry Pi in it. It was expoed last month at the Sun ‘N Fun in Florida, and it’s exactly what the pilots out there would expect: a flight system running on a Raspberry Pi. It was installed in a Zenith 750, a 2-seat LSA, registered as an experimental. You can put just about anything in the cabin of one of these, and the FAA is okay with it. If it’ll ever be certified is anyone’s guess.