So I finally have my quad put together and everything seemed okay, but I cannot get the quad to arm without the USB cable attached to the APM. I am running Arducopter 3.2 on an APM 2.6, Turnigy 9x Tx/Rx, and HobbyKing Blue Series ESCs.
When the USB cable is attached to the computer, the quad arms as expected and I am able to raise the throttle and the motors all spin accordingly (first video below). However, when the USB cable is removed, the motors just give a quick spin when trying to arm and then do nothing (second video below).
In trying to work through this, I figure the USB provides two things: communication and power. I can’t figure out why the direct communication would help, but perhaps it’s a power issue? I am using the 3DR power module.
Please let me know if anyone has any ideas on what to do. Thanks!