BallastHalo 3
Flight Report
Status
- Landed in France! Found in a field - working out recovery plans
- OnlineRadio.fr - French Radio Amateur Coverage
- Traveled 419km
- Flew for 6hrs 15mins
- Max altitude 30.5km
- Launch Video on Youtube
Report
Setup began at 13:00 at Churchill bar, getting a lock with the lassen was relatively easy due to the presence of a backup battery, other jobs included filling the ballast tank, sealing the top of the the payload and adding space blanket. Other jobs included rigging the parachute and lines to the balloon and payload. Launch was a little late finally being let off at 15:00 exactly, there was slightly more free lift then we wanted as we'd managed to spill some of the ballast before hand and hadn't readjusted our calculations which resulted in a faster ascent rate of 3.5m/s. The ascent of the flight was good, started off getting data with a FT817 and whip outside, once other stations were receiving we retreated indoors - unfortunately couldn't get a good signal indoors but as the other stations were receiving well we gave up from our site.
The 3.5m/s gradually decreased down to ~2m/s and the balloon passed over the western tip of London and then south, passing into the English Channel just east of the Isle of Wight. During the passage over the Channel the balloon's ascent rate began to oscillate between 0.5m/s and up to 3m/s which meant that the flight computer was unable to detect a long enough float and so didn't try and drop any ballast. As we approached France it became increasingly difficult to get complete packets as to many stations the payload was dropping over the horizon, during this period a proper float was established and the master flight board signaled for the secondary board to dump ballast - however at this point it seems that the secondary board stopped working (not sure if related). Finally the balloon burst at an altitude of approximately 30.5km and descended by parachute - a few packets were received of the descent and the characteristic tones on the radio were heard. The payload was found in a field near Sées in France, at present we are coordinating the return - perhaps by post or collection in January.
Data
- Light Sensor
- Day = 100, Night = 0,
- found that sunset at altitude occurs ~50mins after sunset at sea level,
- close to sunset it was possible to see the rotation of the payload as the sensor toggled between 15 and 0.
- External Temperature sensor
- Lowest temp = -53C
- Went below 0 after only 7 minutes at an altitude of 1600m
- Internal Temperature sensor on secondary board
- Lowest temp = -33C
- Internal Temperature sensor down by pump/batteries
- Lowest temp = -23C
- Internal Temperature sensor on GPS (with polystyrene and space blanket)
- Lowest temp = -29C
- Pump Sensor - before we managed to spill the ballast it was reading 105, after the spill it read 75 though it was quite variable between 50 and 70 - not very reliable!
- GPS - good lock throughout - around 8 - 10 sats
- Ascent rate calculations seemed pretty accurate
- Blue - External Temperature
- Red - GPS Temperature
- Green - Pump/Battery Temperature
- Purple - Internal Temperature
Lessons
- Photocells do work well as day/night sensors it was reading 65 during the day and 0 at night
- LED/Photodiode ballast sensor isn't very stable
- i2c can be an arse
- Not sure a secondary board is really necessary
- Big improvments are needed in float detection and ballast logic
- Provide pseudo-code to help followers know what should and shouldn't be happening
- Individual insulation with polystyrene and space blanket is good at keeping in the heat
- Batteries run warm so keep important things near them
- Have a funnel to fill the ballast tank
- Need a better hotwire cutter
- More planning should go into construction of payload case - needs to be better sealed as well
- Should contact potential listeners in advance can't rely on last minute emails
Forecast
Aim
- Test ballast tanks that might get used for AtlanticHalo Trans-atlantic flight
- Achieve float altitude, after 30mins drop 100ml ballast, record change in float, wait 30mins drop 100mls, repeat until empty.
Components
- Atlas flight computer
- Lassen IQ GPS Module
- 200-070-006-050 200 Series Peristaltic Pump
- 500ml ballast (denatured ethanol)
Status
- 29/11/09 - Completed Daughterboard onto stripboard - Flickr with notes
- 9/11/09 - Lassen IQ PCB constructed, Daughter AVR constructed, have interfaced internal temperature sensor and also a photocell (day/night detection)
- 26/10/09 - Lassen IQ PCB Breakout board shipped, still waiting for sparkfun order
- Now have i2c working between the 2 boards and reporting temperature.
- Breadboarded the daughterboard
- Have soldered the Atlas PCB
Planning
Construction
Sensors
Ballast Control
Communication
- Main Downlink - 434.075Mhz, 10mW, RTTY, 50 Baud, 350 Shift, Parity 0, Stop 1.5.
- CW Beacon - 434.225, 10mW, CW
Code
- Master AVR Code (Arduino)
- Secondary AVR Code (Arduino)
