The on-board computer will be a Gumstix Connex with a robostix and netMMC expansions. The robostix can be used for GPIOs, servos and analogue inputs. The netMMC expansion has a network port for development and an MMC card for storage. The robostix provides two TTL level serial ports from the Gumstix for the GPS and phone.

GPS will be used for position and altitude. I have a Garmin GPS-25. It is a simple OEM unit, which will reduce weight and size.

IR thermopiles will be used to detect the horizon for attitude information. They measure IR radiation, and since more radiation is emitted from the ground than the sky, the position of the horizon can be calculated. With 6 thermopiles positioned around the glider (2 for each axis), the attitude of the glider can be calculated remarkably accurately.

See other parts of the wiki for more information on communication.

We can use the Siemens M20 GSM terminal (or a Nokia 5110 with a serial cable) to send us a text message of the payload's location and status after it has landed. Ideally it would come back to where it was launched, but there may be problems. We can also send text messages to the payload to control it if need be.

Not a great concern right now. :)