On my 3rd major rebuild of my custom-framed AC2 after losing her to strong wind (stupidity really) and I'm again relishing the opportunity to change further aspects of the design. I'm REALLY hanging to see the OSD integration the boys are working on (come one Jani, hook me up!!!!!). The thought occured that if I wanted to fly really close to the ground in Alt-hold mode, might the sonar be more accurate if it were mounted on a servo plugged into the Tilt output on the APM? That way if she's really moving, and at an extreme pitch, it'll still be pointing directly at the ground. Or have you clever clogs somehow written an algorithim to compensate the Sonar reading based on the angle of attack?
Damn I love this project, best fun I've had in ages!