UWCS is currently collaborating with Warwick Aerospace (formerly Warwick Rockets) to build and launch a high altitude balloon (HAB) consisting of a payload of some electronics attached to a large helium filled balloon. Most HAB projects reach about 100,000ft before the pressure gets too much for them and they explode before plummeting back down to earth.
We actually started working on this last year, but a number of technical setbacks and poor planning meant that we didn't finish it before the end of term three. This post is mainly going to focus on what we've done so far, so that part two can pick up the action from this year.
The main reason that the project (later named the MilePiClub) failed to get off the ground became apparent when we stopped to look at the equipment we had selected. It turns out that using an Arduino GPS unit, an Arduino GSM unit and an Arduino radio module with a Raspberry Pi was not the best of ideas (I still don't quite understand how none of us noticed this). Nonetheless we struggled on, but it was the technical challenge of coercing all of these hardware modules to do things that they weren't intended to do that made us miss our end of term deadline. As a result of this we've decided to swap to an Arduino controller, which should reduce the amount of hair tearing considerably.
The payload in it's entirety is actually a fairly complex thing. Using GPS to determine its location, the unit then decides whether to use Radio or GSM (text messages) to relay this back to base. Footage from the camera is saved to a memory card. Added to this is the concept of fault tolerance - what happens if (read: when) the GPS unit loses it's satellite lock and stops working? What if the micro controller reboots halfway through the flight? That last one has actually been known to happen with the RPi...
Launching a HAB requires liaising with local air traffic control and filing a flight plan with the CAA, although that's more of a flight intention. Average flight time is 2-3 hours, after which you can only hope that your payload doesn't land in too tall a tree. There's normally a tracking team in a car who are receiving regular updates from the balloon as it travels. Once the altitude is too low to use radio, communications switch to GSM for a more reliable link close to the ground.
Github: https://github.com/warwickrockets/MilePiClub
