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Long duration flight taking advantage of east to west 30km high altitude winds. Aiming for launch before 4/6/12.


  • 434Mhz RFM22b Tracker
    • Arduino
    • RFM22b
    • Ublox GPS
    • Continous Telemetry
    • 10mW over UK, 100mW out to sea
  • APRS Tracker
    • Based on stripped Baofeng UV-3R Handheld
    • Arduino - PWM to create tones and control radio
    • Aim for APRS packet on Europe - 144.800, APRS Sats 145.825 and North America 144.390
    • May require qrptracker to known when Sats overhead
  • Float Valve (phase 1) & Ballast (phase 2) system
    • uBlox GPS + PIC + RFM22b
    • Servo operated valve


  • Build RFM22b tracker - jcoxon
    • Replace V Reg - jcoxon
  • Code for 434 tracker - jcoxon
    • Fix higher power - jcoxon
  • Order UV-3R radio - done from HK, dispatched
  • Strip down UV-3R
  • Run on energizer lithiums
  • check if UV-3R can do packet from ATmega
  • Test ISS uplink via APRS
  • H2 vs He
  • Simple enclosure
  • Payload design
  • Geofence UK, APRS only turns on when out to sea
  • Vent valve to maintain altitude - Rocketboy
  • ?Ballast


Launch 1 26/5/12

  • Aim to launch 26/27 May 2012 - to test float capabilities
  • He 1600g Balloon
  • Single 434Mhz Tracker
    • Setup to tx 10mW over UK, up to 100mW out to sea
    • Test Eurus code
  • Current Status
    • Payload setup, working
    • Needs payload box, power supplies, testing,
    • Range tested - works well at 1.5km on ground, can hear signal at 2.3km
    • Test todo: Freezer test (with lithiums), long duration test
    • Completed: Payload, antenna,
    • To construct: GPS cable, Payload box, ?backup tx'er
  • Jobs
    • Buy batteries
    • Wire up battery packs
    • Glue battery packs in place
    • Add on/off switch
    • GPS cable (directly solder to GPS)
    • Attach Antenna

Notes for Launch 1

  • 640 = 4.2v (in) 2.1v(out)
  • Therefore to calc battery voltage Batt = Raw / 155
  • Cuts out at ~510
  • Mass = 250g (inc batteries, insulation and antenna)

Launch Day

Relatively easy launch from Lavenham, Suffolk - filled the balloon inside a barn allowing easy calculation of lift. In total had 500g of neck lift aiming for an ascent rate of 2m/s. Payload had a few last minute issues regarding powering up the radio thought to be related to the power switch, also we realised there was an error in the code which detected that we had passed -6.0 longitude to increased the radio power which needed to be fixed.

Launch was at 1603 with some gusts of wind requiring a running launch. It became clear that the radio/antenna wasn't working to full efficiency as the reception of the signal was very directional - this problem effected it through the whole flight. The problem was probably the use of 2 radials and being attached to the side of the payload container. The flight path was west as predicted however once it reached around 33km altitude it turned North and established a stable float at 34.5km. This was maintained overnight with very little altitude loss and the balloon travelled up over Manchester and then turned west over Liverpool. Sunrise was just south of the Isle of Man and it continued to travel North West making landfall over the south part of Northern Ireland. It was here that it passed -6.0 longitude and powered up to 100mW only to find that this killed the radio and no further telemetry was heard.

Many thanks to G0MJW and F6AGV for providing lots of data even at long range especially with the bad payload antenna.

  • Flight time was 19hours (until signal lost)
  • Float time was 15 hours (between 34 and 36km)


  • 4 radials
  • function to check radio is working
  • ? just use NTX2
  • don't bother with higher power (killed setup)
  • integer lat/lon worked?

Eurus 2


Similar flight to Eurus 1 however to attempt to float at a lower altitude (25km) in an attempt to take advantage of the faster winds.


  • Howyee 1600g balloon (aim for 2.5m/s ascent)
  • Neck valve + controller micro
  • Parachute
  • 434Mhz Tracker (similar to Eurus 1)
    • Based on uAva (Atmega328, Ublox 6, RFM22b)
    • Running plan13 for predicting ISS paths
    • Improved antenna

Eurus 2 Payload

  • Based on a uAva board
    • ATmega328 with arduino bootloader
    • RFM22b
    • Ublox MAX-6 GPS with chip antennna
    • Running at 8Mhz 3.3v
  • 1/4 Wave GP (4 radials) Antenna
  • Mass = 211g


$$EURUS,Count,HH:MM:SS,Latitude,Longitude,Altitude,Sats,Lock,NavMode,Battery Voltage,ISS Az,ISS El,APRS Status,APRS_Attempts*CRC16

Code can be found here: Github Combo.ino

The payload is setup to calculate the Az and El of the ISS in relation to the balloon and if it is in view it will send APRS messages. The payload however will not be carrying a capable radio to communicate with the ISS, partially as this is a high risk launch testing the new valve but also the ISS has changed its packet system from 2m to 70cm which makes it harder to get a relay. We'll still test the flight code as it may come in useful in the future.

Also the radio will be reset every 50 strings as well as the GPS being 're-setup' to avoid any problems with the individual components reseting and losing their configs.

Eurus 3

projects/eurus.txt · Last modified: 2013/07/22 17:16 by jcoxon

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