When I comes to hardware there is a lot to think about. I settled on Samsung Galaxy Note 2 because you can plug an external antenna there.The balloon itself would have to be 1.2kg one, this will enable us to have payload of 1/2 a kilo without a problem. I am also thinking a a sun battery, but it could be an over kill, as I plan on adding a duracell pack to the phone. I’m also thinking of a back up comms unit, it could be 4G MiWi, the phone could be paired to it, WiFi requires less power consumption and once it dies it will automatically switch to 4G.
The init will be attached to a parachute, I will also need 5 x 0.41 canisters of helium to give us more than enough payload capacity.