Failsafe RC-receiver VS Copter (Mission Planner-setting)?

ArduCopter Copter 3.5
21

There is a current post about a fail safe crash. His logs show the motors were disarmed during failsafe, but it was in loiter mode. Switched to RTL,but disabled the motors. Luckily the aircraft recovered and the motors rearmed. I don’t get cutting the motors in any mode unless the craft is landed. Is it to prevent a dangerous fly away?

22

One time when we tested to pull the SBus-cable out of the RC-receiver on the table, the motors stopped. It worked then again the second time we tested. We thought it disarmed at the exactly same time we unplugged the cable. Now I am as unsure as you. Is there a possibility that the multicopter flies OK and then there is a glitch and the motors disarm when having the failsafe at throttle off-position. That is dangerous with a 7 kg hexacopter!!!

23

I now have a quad with an APM 2.8 (running APM:Copter 3.2.1) I am configuring the Failsafe on.

  • Throttle goes from -100 to +100% (as default, no trims)
  • Receiver Failsafe is set to pwm = 1000 in Mission Planner (with trims lowered from 0) and saved, then trimmed back to 0.
  • The rest of the channels are HOLD.
  • FS PWM is set to 1050 in Mission Planner.
  • When transmitter is ON, the Throttle PWM = 1110. (-100%).
  • When the transmitter is OFF, the receiver goes into Failsafe and Throttle in Mission Planner goes down to pwm 1000 when I turn off the transmitter.

But…
When Arming and revving up the motors (Stabilize mode) and holding it in the air (no props) and shuts of the transmitter, it disarms!!! When shutting off, the PWM for the Throttle goes down to 1000. What happened with RTL?

What have I done wrong?

24

Without a .bin or .log file from the APM its a bit hard to tell.
Could be quite a few factors.

25

It’s probably because its so close to where it was armed.

26

Is it possible it disarms if it is on the ground?
Best way to test is to “hover without propellers”?
The same thing have happened for two multicopters now (on the desk).
It just disarm.
Both revving, but not maybe hovering-rpm.

27

Put the props on and go fly it. Testing without props is a complete waste of time…

Another reason the motors will disarm is when the flight controller thinks it is on the ground…