For the last week i have successfully flown my Twinstar with the APM. Everything was tuned and i had developed a good routine for setting things up in the field before flying. Yesterday the plan was to test a long endurance flight (25 min) that also used the relay to reset the XBee to keep the telemetry link for the entire flight.
But this is what happened...
The Twinstar comes with a small PCB that houses connectors for the motors and ESCs. The motor connectors are constructed in a way that they can't be connected the wrong way, but you can accidentally connect plus to minus and vice versa anyway which i found out... the connectors touched for just a split second, but that seemed to be enough to brick my APM. Mission Planner will not talk to it any more. The Arduino IDE doesn't like it either... I don't think the Mega 1280 is that sencitive, and i will investigate that further.
Fortunately i had a spare APM lying around... Some rewiring and a firmware upgrade and I was good to go. Almost...
I needed to recalibrate my radio for the new APM and ran in to all sorts of trouble. When i finally got everything in order i just wanted to do a last test of everything before flying.
It turns out that my ESCs needs a lower PWM than what my radio could give them (Without trimmint the throttle down... ) to keep the motors still. When i connected the ESC the motors spun up, one propeller hit the canopy and sent my xBee for a flight on it's own. Fortunately the xBee survied and i only need to replace one propeller.
Lessons to learned:
* Replace stock power connector on the Twinstar!
* Save your APM settings regularly. If you need to replace or reflash it you will need this file. Otherwise you need to start all over with the tuning process.
* Recalibrate radio after firmware uipgrade. Don't rely on the settings in your stored settings file.
Well i guess it's part of the hobby. New props are on their way and this gives me a reason to order a APM with the Mega 256 Kb chip.
Over and out.