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Fill Tube

14 09 2014   //   Written by Yannick   //   Classified in : HAB  //  Tags : balloon, cord, fillTube

I builded the fill tube folowing ideas of this UKHAS wiki page.

As I don’t have something to create a grove, I used a PVC waste water plug that already have some kind of grove by design.

  • I strongly glued the flexible fill on it.
  • To close the remaining space, I added some wet newspaper sheets to create a temporary “wall”.
  • I used a hot glue gun, and let the hot glue fall all around the both sides of the newspaper.
  • I drilled a small hole to attach a nylon cord to be used for weighting and to secure to the ground bebore launch.

I was very happy with it.
Looks strong and very easy to build.

Raspberry Pi USB Hotplugging

19 08 2014   //   Written by Yannick   //   Classified in : HAB  //  Tags : USB, HotPlugging, capacitor

The payload had a backup transmission using a USB 3G/SMS dongle (Second hand / 10€) to send SMS with coordinates in case of failure of the NTX2.

As it is useless and waste of battery to power the USB dongle during all the flight, I used a script to power it (using a GPIO and a relay) only when the payload was back to the ground (altitude bellow 2 Km).

But when testing my script and the “hot plugging”, I noticed the Raspberry PI A failed (freeze / reboot) everytime the USB 3G/SMS dongle was plugged.
After some investigations, I found the folowing links explaining about the “inrush current” and the Voltage Droop”


The USB.org whitepaper explain:

I n accordance to the USB Specification Revision 2.0, the VBUS power lines must be bypassed with no less than 120µF capacitance of low-ESR capacitance per USB port.

So I soldered a “Low ESR” 220uF and this fixed the issue \o/ !

Note: this problem was known by the RaspberryPi foundation as it seems to have been fixed with the new version B+ that have “better hotplug and overcurrent behaviour”.

Uggy payload - Data analysis with gnuplot

12 06 2014   //   Written by Yannick   //   Classified in : HAB  //  Tags : altitude, pressure, temperature, gnuplot


We previously get some data collected by Habitat server, but in this post, we are using Gnuplot to plot our data.
This is data that has been stored on the payload, not only the data sent to Habitat server during te flight.

Data sent during the flight do not contain:

  • Data for every minutes of the flight
  • Data about some sensors (like pressure)

To have my files in the same time zone as Habitat, I subtracted 1 hour with date command as bellow:

for i in `cat toto | awk '{print $1}'`; do date -d "$i 1 hour ago" | awk '{print $4}' >> tutu; done

Use of gnuplot

Gnuplot can be installed on Debian with a simple apt-get install gnuplot.

Exemple of commands used to create the graph.

gnuplot> set title "Altitude"
gnuplot> unset key
gnuplot> set xlabel 'Hour'
gnuplot> set ylabel 'Altitude'
gnuplot> set grid
gnuplot> set xdata time
gnuplot> set timefmt '%H:%M:%S'
gnuplot> set format x '%H:%M'
gnuplot> plot 'altitude_data_UTC.txt' using 1:2 w lp
gnuplot> set y2tics
gnuplot> plot 'altitude_data_UTC.txt' using 1:2 w l, 'pression_data_UTC.txt' using 1:2 w l axes x1y2
gnuplot> plot 'altitude_data_UTC.txt' using 1:2 w l, 'temperature_data_UTC.txt' using 1:3 w l axes x1y2 ,'temperature_data_UTC.txt' using 1:2 w l axes x1y2

We are lucky, the graph created is similar to previous graphs from x-f.lv

UGGY Payload data

Temperature vs altitude

2 DS18B20 sensors were used (Internal/External)

Pressure vs altitude

BMP085 was used.
It is rated as:

Pressure range: 300...1100hPa (+9000m...-500m  above sea level)

So.. I was expecting nothing below 300 hPa… but instead I get something that makes sense up to 34Km… :)

Altitude plotted is from the GPS receiver. (NOT a guess from the BMP085 from calculated pressure)

Uggy payload - Temperature and ascent rate

25 05 2014   //   Written by Yannick   //   Classified in : HAB  //  Tags : ds18b20, temperature, ascentRate, altitude


Payload has been launched with 2 DS18B20 temperature sensor.
One was inside and another one outside.

There are several ways to “study” graph.
One easy way is to use data from Habitat available on on x-f.lv

External temperature

  • Lower value was -40°C around 10 000 meters. (And possibly after burst)
  • Temperature drop again when the payload is falling very fast after drop.
  • As it is data from Habitat, not the payload itself, there are some missing data.

Internal temperature

  • Lower value is -4°C

Altitude / Ascent rate

  • Ascent rate was around 5m/sec (Expected was 5.5m/sec)
  • Descent rate after burst is 40m/sec
  • Descent rate when landing was around 6m/sec (expected with the parachute size)

UGGY payload signal receivers

25 05 2014   //   Written by Yannick   //   Classified in : HAB  //  Tags : receivers, callsign

Who received the UGGY payload signal ?

This data can be extracted from Habitat Server

CallSign Location Other Min altitude Max altitude
G8DHE Worthing, West Sussex, UK Website 14 150 30 076
PE2G Netherlands 25 164 33 506
jijdaar Netherlands 23 047 30 076
PB0AHX Netherlands Website 27 472 33 632
RAGONDIN French chase car Scottish operator ;) ~ 120 33 130
Uggy French chase car website ~ 120 2 811 (then moved as driver)

Great to have listeners outside France ! Thank’s guys :)

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