I am using APM2.6 with 3.2.1 firmware and 3DR power on a F450 quad.
Here is the symptom:
-hold thr stick for 5 sec to the right and the quad arms.
-power up, the motors run fine for few seconds and shuts off gradually. Sometimes if I cut thr to half, they will turn off. its seems, I have intermittent control over my thr.
- I was able to hover the quad for few seconds, but it stopped responding to my thr command.
- the quade is in "stabilized mode" thru out these sequence.
Have you been able to figure this problem out?
Did you check the 'copter's battery voltage prior to arming the motors? And did you do so right after having experiencing this problem?
As Jerald said, this sounds like a battery issue. Be sure to check the voltage of your battery before and after every flight.
Yes, the battery voltage was set for 4-cell and I was testing it with 3-cell. Once I switched to 3-cell (10.5 V), it flew fine.
I guess APM was behaving correctly by landing the copter after low voltage.