I have read a couple of discussions on this already but it seems no one has asked about this for over a year and I wondered if there have been any advances that would make this easier since then.
So last year my school sent a weather balloon to space with a payload containing various sensors and a camera, and after a lot of searching with a yagi we managed to find it! This year we want to do something a bit more interesting, and so plan to take another balloon up with a glider, and have it autonomously glide down to a predetermined location. We have a skywalker x-5 that we've assembled and got flying, and decided on an APM. (We decided against the pixhawk because it's outside of our budget). We are ordering an neo-6m gps unit for it, and aren't sure about whether we should get an airspeed sensor or not. Should we get one? And will we need to modify any of the code to make the APM do what we want or can we just put it into RTL mode on takeoff and have it glide down once it is detached from the balloon?
Any help is greatly appreciated.
A couple of other things we do is we use ADSB for avoidance of other aircraft and we use live satellite weather data. We also use GPS prediction software to determine the satellite constellation coverage during the planned launch window. These are safety features the FAA appreciates and they are useful tools others could use to satisfy the FAA your concerned about airspace. (In order to get a waiver to fly legally)