Arducopter is open source: https://code.google.com/p/arducopter/ https://code.google.com/p/arducopter/ You can tinker around with the source code. Memory of th

Arducopter is open source: https://code.google.com/p/arducopter/ https://code.google.com/p/arducopter/ You can tinker around with the source code. Memory of the APM is limited, though.