Finalizing the Electronics Package

     Instead of using an Arduino Uno as the primary microcontroller for the flight computer, we went with the Arduino Nano which has more analog ports and is much lighter (without the screw terminal adapter). The use of screw terminals seemed rather promising until it was time to actually package the electronics system. Because of our desired weight limit and the design of the payload, wire management became an issue and possibly contributed to the ultimate failure of the electronics system.

     The electronics package in its entirety can be seen to the right in the above picture. This system consists of two BH1750FVI Light Intensity Sensor Modules, an ADXL 345 Accelerometer, DHT21 Humidity/Temperature sensor, UBLOX GPM GPS, 10DOF MS5611/HMC5883L/MPU6050/MWC Flight Control, and the LC Studio SD card reader.

     The above picture shows the Eagle Flight Computer and its temperature/pressure sensor. Its purpose was to be our backup flight computer in case the one we constructed failed...the good news is that we got temperature and pressure data.

     In order to ease our task of finding the payload after the it had landed (prematurely in our case), we had attached a siren to the payload that was powered by a 9V battery. It could be powered on by a simple switch, and proved to be quite beneficial to the recovery aspect of the project.

     In addition to using a switch to power on the siren I mentioned in the previous paragraph, we also used a switch to power on the Eagle Flight computer and the electronics system that we constructed. In order to tell that the systems were powered on, we attached a 5V LED in parallel with the Arduino Nano. I soldered a 1K ohm resistor onto the positive lead of the LED so that it would not burn out. When the switch was closed, the LED would light up telling us that the system was running.

     While the electronics worked very well outside of the payload, they did not work so well when they were packaged in the manner that can be seen above. In the future, I suggest that the mechanical and electrical teams work together in a way that prevents a mess like this from happening...

Additional things to consider for the next launch:

• Battery compartment for all the electronics.  This should be accessible from outside the balloon. 
• At most two compartments in the payload.  One for electronics and one for batteries.  Use foam inserts for shock mounting. 
• An alternative to switches.  These could be jumpers or ???
• Batteries being sized to allow for 30 minutes of testing while balloon is inflated and prior to launch
• An alternative to simply using zip ties in order to fasten the payload to the balloon.  When the zip ties failed, the payload reentered ballistically.
• Keep the center of mass toward the bottom of the payload
• Have the science team look over data sheets so that they don't harass the electrical team leader
• Use a PCB for electronics to reduce wiring to nill.
• Radio team needs significantly more work on RF solutions.
• Use high powered LEDs in case of having to search for the payload in the dark
• Attach glow bracelets around the tethering  of the shade structures at camp to reduce the trip hazard. 

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