Ardupilot Arming Philosophy/Ideas

I strongly advised against switch arming in favor of stick arming because of the multitude of crashes we see here due to unintentional disarming in flight when switch arming is employed. It’s literally the first thing I look for when analyzing a crash log, and it’s often the smoking gun (the other most common reason being power loss to the autopilot, often due to misconfigured battery monitoring or poor battery health).

To avoid such looming catastrophe on my own craft (not that I don’t trust myself, but more that I simply don’t want to even think of accidentally bumping a switch that could cause irreparable damage), I use stick arming almost exclusively on air vehicles, and I employ a logical switch algorithm to my EdgeTX transmitters to toggle an otherwise unused ExpressLRS Ch5, such that I get all the benefits of ELRS while mitigating the risk involved with switch arming.

I do understand the inherent risk in NOT having an immediate disarm/emergency stop feature on my transmitter, and I do typically employ one on the same switch that I use for Rover arm/disarm whenever I test a new airborne build. That switch tends to go otherwise unused, such that I keep some semblance of muscle memory tied to the integrity of that specific switch. But I still shy away from keeping arm/disarm or emergency stop on a switch after initial testing.

It all comes down to risk management, and the risk that I take by eliminating instantaneous motor stop has nearly bitten me a time or two when my bravado exceeded my ability at times, resulting in crashes where I had to await the stick disarming delay and/or rely on the firmware to detect a no-longer-flying condition to spin the motors down from a saturated high (screaming) state after ground impact.

All of that said, @xfacta’s discussion of using a throttle cut switch has me inclined to employ that strategy going forward. There’s good info on the wiki page - look for the section discussing FS_THR_VALUE. Seems this keeps all desired functionality intact while avoiding an instant airborne kill. I’ll likely tie ELRS Ch5 to this switch as well, while keeping RC5_OPTION unused or tied to my LED scripts as desired.

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