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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, h
ardware under evaluation and issues
- Pressure sensors
- ELVR-L01D-F1RT-I-NA5F, output 0÷4.25V
- ELVR-L10D-F1RT-I-NA5F , output 0÷4.25V
- BARO-A-4V-MINI-PRIME , output 0÷4.25V
- Analog to digital converter
- 8 ch ADS8344N/1K 16 bit, external Vref
- 8 ch LTC1293DCN#PBF 12 bit, external Vref
- 8 ch AD7856ANZ-DIP(SOIC-24) 14 bit, Internal Vref 4.096V
- Precision matched resistor-divider MAX5492RA01100, ratio 1.1
- Standard Clock Oscillators DIP-14 5V 4MHz
- Arduino nano microcontroller
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
Issues: Sofar none
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?
- True airspeed
- Angle of attack
- 20 degree
- The angle of attack is not necessary
- Angle of sideslip
- 20 degree
- 30 degree
- Outside air temperature
How to measure?
Full range uncertainties
- Airborne 3 m/s
- Bike 2 m/s
Angle of Attack/Sideslip
- 2 deg
- 2 degrees Celsius
- 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
- Range 1900 Pa
- Range 231 Pa
- One temperature sensor, it is needed to correct air density value
- -20°C to 60°C range
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
No. 1 Integrated data acquisition system by Analog devices
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
No.3 Differential pressure sensors All Sensors ELVR-L01D-F1RT-I-NA5F , 1″ H2O , 250 Pa range.
Nos. 5 Differential pressure sensors. All Sensors ELVR-L10D-F1RT-I-NA5F , 2500 Pa range
Printed Circuit Board: KiCad Eda