BallastHalo 6

To finally test the ballast tanks at altitude! BallastHalo 5 nearly did it - the balloon floated, the pump worked and we detected the change in ascent rate however the sensor didn't work, we dumped all the ballast at once and lost the payload. Improvements include

• A new Atlas PCB (smaller this time and with more headers)
• A PCB for the FSA03 GPS module with backup battery
• The smallest peristaltic pump in the Williamson Pumps 100 Series
• Better insulation on the radio
• Updated code to stop ballast drop when float is broken.
• Code to place zero into single digit time fields
  • Ublox drop the spare zeros from the time field so 13:1:9 rather than 13:01:09, this confuses the tracker so need to add in the required zeros.
• Using a micro switch to detect the rotations of the pump

• Ordered a new Peristaltic pump from Williamson pumps - 100 series 3.0mm Silicone tubing + 6v 35rpm Motor/Gearbox here
  • This is the lightest pump they have, the motor/gearbox itself weighs 106g and then the pump itself is ~40g
  • Total cost with some more tubing and barbed connectors + p&p = £60
• The aim will to make the whole thing very intergrated but also light - one option would be to replace the metal bracket with a plastic one - perhaps could use a makerbot to produce one.
• To measure rotation my current plan is to use a microswitch - both the hall sensor and photogate will have thresholds that may be affected by temperature - the switch will either work or not work. The switch will be triggered by an cam on axle connected to the pump. Again we'll use an interrupt to measure the number of rotations.

• Purchased 2 FSA03 GPS modules (One spare) from Sequoia.
• An FSA03 was used on BH5
• Also fabbed a breakout board for the module Flickr
  • Is all through hole, the GPS module fits snuggly and once soldered in place is very secure - there have been reports of wobbly antennas so it'll be worth putting a a blog of glue on the back to keep it in place.
  • 4 pins at the bottom are 3.3v, Rx, Tx and GND.
  • Also has an LED + resistor, backup battery on the back and a reset button.
• Soldered up on 13/9/10 - worked immediately.
• Still need to add the battery holder + reset button.

• With the loss of BH5 I've run out of flight computer PCBS (the 1st is up a tree in Staffordshire) and so I've ordered 10 more from seeedstudios. I've redesigned the PCB to now be 2 layered and also have added more breakouts for the various sensors and GPIO that are required. I've also added a transistor + resistor heater to try and maintain the temperature of the radio crystal so will have to see how that goes.
• Will post more images soon.

• Awaiting flight computer PCB (design sent to seeedstudio))
• Continue to develop homebrew crystal oven
• Order new NTX2 modules from Radiometrix
• Construct payload case

• Temp sensors
  • 2x 3 sockets
  • Get addresses
  • Add code to check for bogus data
• Crystal heater
  • make thermal mass
  • PID controller - http://www.arduino.cc/playground/Code/PIDLibrary
  • tune
  • test in freezer
• finish antenna
• finish payload
  • Position for GPS module
  • Position for backup beacon ?in lid
  • Spaceblanket but leave gap for GPS
• make gps cable
• Backup beacon
  • 434.650 ntx2
  • 3.3v atmega168 + bootloader
  • fix code
• buy lithiums (12xAA)
• make vent
• if found signs
• recruit listeners
• organise launch team
• get 1.5kg balloon
• weds - email ukhas list + contact southgatearc
• monitor weather

• Sunset 16:14UTC
• Therefore sunset at altitude ~ 17:15
• at 2m/s aiming for 20km altitude it'll take 10000seconds, 167minutes, or 2hrs 47minutes.
• Launch should therefore be 17:15 - 2:47 = 14:28

• If at 3m/s launched at 14:28 we'd float at 30km.