Hi all,
I have a tricopter that I’ve recently assembled and starting to tune. The problem I’m having is when arming/disarming the tilt on the tail servo puts the blades into the ground. While I can increase the height from the ground or put limits in place for this servo, Is there an option to change the channel used to arm the apm ?
If its in the parameters I’m afraid I’ve missed it a couple of times.
This is using a pixhawk px4 with apm firmware.
Thanks
Jason.’
Hm, put longer feet to the copter? 
I had a somewhat similar problem in that my servo travel on my tricopter is limited and I didn’t want my servo hitting hard against the stops. I dealt with it by adjusting my RC transmitter to limit the range of travel of the servo channel.
One catch to be aware of. In order to arm the throttle the yaw PPM must be greater than a certain value. If you limit the yaw PPM range too much it won’t arm as the PPM signal will be too low. I found the allowable values deep in the APM code at one time, but I can’t seem to find them again at the moment. I apologize for that. Just be aware that if you do limit your RC transmitter’s servo travel, and it won’t arm, you need to increase the travel range until it does.
EDIT: Found it! It’s in motors.pde. For the copter to arm the rc channel must be between 1300 and 1700. So you can adjust the limits on your RC transmitter, limiting your throw, just don’t go below 1300 or above 1700. Worked for me.