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Short notes on the brainstorming concerning the next to come air data system.

The page will be updated on an irregular basis, it is a work in progress.

If you are interested in providing some hints about electronics design/other just contact us or post your suggestions.

Erik
Air data compute Github repo

Click the 3D model to rotate

At a glance, hardware under evaluation and issues

Sensor’s board

On the sensor’s board, there is one multichannel ADC that handles sensors signals conversion and communications with the local microcontroller (serial 3/4-wires preferred). The local microcontroller handles one USB connections as a slave device.

Issues: To find an ADC IC that can be hand soldered. Six channels minimum (good also 2X3 Ch or so) single ended. Single powered, 5V range. Internal reference and analog input range 0-5V. Digital interface to match on board microcontroller voltage.

Air Data Computer /ADC

Raspberry pi 3 B+

Issues: Sofar none

Leading idea

We need an ADS design that can be implemented by average level makers. So we should address assembly related issues and contain the budget. A shortlist of key points.

  • Capable to drive a Multi-holes probe MHP, 5 holes
  • All the electronic and mechanic design files, in free formats, should be available to the users
  • If it is not possible to use DIY printers to manufacture a specific part, then the 3D print should be possible with common 3D online print services
  • Electronics components should be available worldwide through online retailers
  • Printed Circuit boards should be easy to be printed by online services
  • The parts should be solderable by hand
  • Robust data acquisition system. Multichannel.
  • Able to support airborne operation and bike operation. Of course with a little hardware reconfiguration
  • Scalable. Users should not be forced to populate the whole sensor array
  • Users can change sensors and sensors ranges to accommodate their application
  • Air Data Computer, 3.3 Volt Teensy 3.6 Microcontroller
  • 5 Volt Sensors, Analog sensors
  • Operating sample frequency 50Hz
  • New ADC should be able to easily interface with Asgard ADC

What we want to measure?

How to measure?

6 Holes MHP

Full range uncertainties

  • Airspeed
    • Airborne 3 m/s
    • Bike 2 m/s
  • Angle of Attack/Sideslip
    • 2 deg
  • Temperature
    • 2 degrees Celsius

Sensors

  • One absolute pressure sensor for static pressure measurement. Atmospheric pressure range, 60000 Pa to 110000 Pa
  • Five differential pressure sensors. One for each probe hole. The measured pressure is that between the probe hole and the static pressure
    • Airborne
      • Range 1900 Pa
    • Bike
      • Range 231 Pa
  • One temperature sensor, it is needed to correct air density value
    • -20°C to 60°C range
Air Data System Layout

Layout

Two separate units. The ADC and the sensor’s board.

A USB cable connects the sensor’s board to the ADC. On the sensor’s board is present a microcontroller. The ADC will power up the satellite sensor units.

The ADC will be upgraded to be a single board computer.

Candidate electronics components

Common hardware

No. 1 Integrated data acquisition system by Analog devices ADAS3022BSTZ : 16-Bit, 1 MSPS, 8-Channels (Reference circuit)

No.1 Integrated data acquisition system by Analog Devices AD7606BSTZ-6

No.1 Digital I2C mux NX PCA9540BDP,118

No 1 Barometric pressure sensor. BARO-A-4V-MINI-PRIME All Sensors. Range 60000 Pa to 110000 Pa.

No 1 Temperature sensor. TMP36GT9Z Analog Devices. Range -40°C to 125°C

Bike application

No.3 Differential pressure sensors All Sensors ELVR-L01D-F1RT-I-NA5F , 1″ H2O , 250 Pa range.

Airborne application

Nos. 5 Differential pressure sensors. All Sensors ELVR-L10D-F1RT-I-NA5F , 2500 Pa range

EDA software

Printed Circuit Board: KiCad Eda

Enclosure: FreeCad

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