I have a few quadcopters and normally when I power them on the ESC's beep once. After installing the Pixhawk 2.1 I noticed that when I plug the batteries in the ESC's beep one and then beep a second time a few seconds later. Why might this be…

I am only have GPS2 wired up to my pixhawk because of the way I had to wire things, however mission planner says :"GPS: No GPS". Can I use pixhawk with only one GPS in the GPS 2?

I'm looking to build a DIY headtracker found on this site but need help determining how to chose the correctly sized servo for the pan/tilt mount. 1) What numbers should I be looking at on servo specs that correspond to the size/weight of my…