I need some advice - I modified a Parallax Elev-8 quadcopter by fabricating a boom from alunimum U-channel stock to hang a Tarot 2 axis gimbal/GoPro camera. The aircraft is using an APM 2.6 FCU, with external GPS/compass, telemetry and a small video transmitter. The weight is approximately 4.4 lbs. I'm using the stock motors - KA 1050kv Outrunners with 10x4.7 propellers. My problem is after only about 2 1/2 min the voltage failsafe kicks in and it wants to land. Here is a picture of the voltage log:
My question is this: Is it normal for voltage to drop immediately like it did on takeoff? Should I lower the voltage failsafe threshold?
Here's a pic of my aircraft: