Both sound sources: whirring and selected sounds:



Mixing board, line out socket and main amplifier: 



3 photos showing beginning of building the harness to support the balloon:




GPS/LCD board with basic info on screen:

Speed test experiment:



Temporary supports added to either the top or bottom:


Experimental rig for measuring speed of the motors, each has 3 tests and the driving circuit can be tuned for consistency (invalid data shown, not in use yet):



2nd method again for motor speed assessment - rotary encoders and read on a separate PC to the one controlling the motors: