One of the very first outdoor position hold tests with my tricopter. The sticks were not touched for 2*13 minutes (two packs of batteries). This is pretty much preliminary, but it already works in principle. The parameters are not yet optimized, they were just guessed by looking at the signal output. Still quite a long way to go to make something useful out of this, but small successful steps help me keeping the motivation up :-D . Details in my blog:
shrediquette.blogspot.com