"I have same problem, except it's the opposite - it's too jerky in acro mode - some hints anyone?"

"Hello, Tom, for your first issue, i experience the same problem where throttle control is extremely binary and not progressive at all as it should be to allow easy control. I have a post on this…"

"We have a similar problem ~ 1 click and the copter goes up, one click down and the copter goes down - we changed the throttle P from 0.250 (default) to 0.0 and it made no difference.  It's crazy ...ha... I feel like taking a file and…"

"Another post showed interference with motor power wiring which improved greatly when APM was relocated away from the wires. (Even more so for  magnetometer). I put an aluminum tape shield on my fiberglass intermediate separator plate which is…"

"Same problem here: my gps dances around whole neighbourhood when indoors and I suspect this may be source of my problem with copter doing chaotic dance in loiter mode. Is there any way to fine tune it, or is it because of how the gps is mounted…"

"You are correct!  The long beep isn't as long as you would expect it to be.  But double beep, then lower the throttle, then another beep, then the motor is armed, has worked for me."

"Thank you very much for your response Ellison, Thank you for clarifying throttle, I thought stabilize was just an implementation of the stabilize rate and angle PIDs mixed with throttle stick position for maintaining and adjusting altitude and…"

"I just built a 540mm frame,  ntm 26-28a motors 30amp esc.  I get a perfect gps lock and can not fly in stabalized simple mode.. "

"I've never had problems with my GPS location jumping around.  Even indoors, on the top floor of my house, with big windows, I don't have that issue. I should clarify about the throttle PID. I should be more specific. It's used…"

"Hey Stephen, While Doing Manual ESC Calibration according to http://code.google.com/p/arducopter/wiki/AC2_ESC, step 5 says "You will hear a musical note and then 2 beeps. After the two beeps drop the throttle to full down. You will then hear a…"

"Hi Tom, Get a GPS lock while your USB is hooked up, if your experience is similar to mine, you can watch your Quad in the mission planner flight data section wander around and make periodic excursions even with 9 satellites showing. I believe…"

"Thank you all for the discussion above. For shure many of my kind of pilots, pedestrians, listen and learn. lars  "

"Brilliant! Thanks very much!"

"Tuning throttle is for all modes.  But loiter is an autopilot mode, so throttle will be controlled automatically to lock in an altitude and location. Increasing P will make that control more sensitive, decreasing will make it less.…"

"Thanks Ellison. Will adjusting the Throttle Rate P make a difference in the stabilize mode or Loiter only? I'm fairly happy with the response in Loiter mode, but Stabilize is horrible. I also need to tune the Roll and Pitch as the copter seems…"

"Yes, sorry, my bad.  "Throttle Rate P". If you are flying Stabilize mode, and want to tune the P you can adjust the Stabilize Roll/Pitch/Yaw P's.  Same for Rate.  Rate means only for gyros."