I'm dying to see some more details! What model plane, how does your stabilization algorithm work, how is everything placed on/in the plane, how do the ARM microcontroller and the original controller work together, etc!
Seems nice at first glance, but where the topics start to get a little less trivial (where, for example, the brokenthorn series on OSdev stop being relevant as well: the harddisk driver), the draft ends.