Air Data Computer

3 Articles

Reverse-Engineering A Shahed-136 Drone Air Data Computer

July 15, 2024 by 22 Comments
Top of the air data computer module, with pressure sensors, RS232 driver and DC-DC converter visible. (Credit: Le Labo de Michel, YouTube)

An air data computer (ADC) is a crucial part of an avionics package that can calculate the altitude, vertical speed, air speed and more from pressure (via pitot tubes) and temperature inputs. When your airplane is a one-way attack drone like Iran’s Shahed-136, you obviously need an ADC as well, but have to focus on making it both cheap and circumvent a myriad of sanctions. As [Michel] recently found out while reverse-engineering one of these ADCs. Courtesy of the Russo-Ukrainian war, hundreds of these Shahed drones are being destroyed every month, with some making it back down again intact enough for some parts to end up on EBay.

The overall design as captured in the schematic is rather straightforward, with the component choice probably being the most notable, as it uses an STM32G071 MCU and Analog Devices ADM3232 RS-232 driver, in addition to the two pressure sensors (by Silicon Microstructures Inc., now owned by TE). The DC-DC converter is a Mornsun URB24055-6WR3.

With the board in working condition, [Michel] hooks it up to a test setup to see the output on the serial interface when applying different pressures to the pressure sensor inputs. This results in a lot of ASCII data being output, all containing different values that were calculated by the firmware on the STM32 MCU. In the drone this data would then be used by the flight computer to make adjustments. Overall it’s a rather basic design that doesn’t seem to have a dedicated temperature sensor either, though [Michel] is still analyzing some details. A firmware dump would of course be rather fascinating as well.

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Reverse-Engineering The Mechanical Bendix Central Air Data Computer

October 19, 2023 by 9 Comments

Before the era of digital electronic computers, mechanical analog computers were found everywhere. From the relative simplicity of bomb sights to the complexity of fire control computers on 1940s battleships, all the way to 1950s fighter planes, these mechanical wonders enabled feats which were considered otherwise impossible at the time.

One such system that [Ken Shirriff] looked at a while ago is the Bendix Central Air Data Computer. As the name suggests, it is a computer system that processes air data. To be precise, it’s the mechanism found in airplanes that uses external sensor inputs to calculate parameters like altitude, vertical speed, Mach number and air speed.

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Asgard: The Open Source Air Data Computer

January 25, 2018 by 14 Comments

We get a lot of awesome projects sent our way via the tip line. Well, mainly it seems like we get spam, but the emails that aren’t trying to sell us something are invariably awesome. Even so, it’s not often we get a tip that contains the magic phrase “determine Mach number” in its list of features. So to say we were interested in the Asgard Air Data Computer (ADC) is something of an understatement.

Now we’ll admit right up front: we aren’t 100% sure who the target audience for the Asgard is, but it certainly looks impressive. Team member [Erik] wrote into tip line with information about this very impressive project, which is able to perform a number of measurements on incoming air, such as true speed, viscosity, and temperature. The team says it has applications ranging from HVAC to measuring the performance of bicycles. We don’t know who’s going so fast on their bike that they need to measure air speed, but of course the hacker community never ceases to amaze us.

Even if you don’t have a jet fighter that could benefit from a high performance ADC such as Asgard, you have to be impressed by the incredible work the team has done not only designing and building it, but documenting it. From the impeccably designed 3D printed case to the stacked PCB internals, every aspect of Asgard screams professional hardware.

Data collected from Asgard can be stored on the internal micro SD if the device is to be used in stand-alone mode, or you can connect to it over USB or Bluetooth thanks to the HC-05 module. The team has even put together some scripts to merge the Asgard’s generated air data with GPS position information.

We’re all for putting high quality sensors in the hand’s of the community and seeing what they can come up with. The spirit and build quality of this project reminds us of the impressive work [Radu Motisan] has been doing with his distributed air quality sensors.

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