Some basic steps for Pixhawk+FBL :
Arducopter Heli Version 3.3.3 stable
Tip#1: calibration of accelerometer is much easier before you put the Pixhawk in the helicopter.
Tip#2: Advanced Compass Setup
states 'Compass orientations are relative to the flight controller, not the airframe !' while MP tells you 'On a PX4 or Pixhawk with an external compass the correct value is zero if the compass is correctly oriented.'
WARNING !!! Remove blades or pinion or motor wires etc.
Insert the Pixhawk between RX and FBL. RC1 = aileron, RC2 = elevator, RC3 = collective pitch, RC4 = rudder, RC8 = ESC, RSC, throttle whatever it is called
If necessary change the TX output (channel number, servo direction) to achieve the correct movements in Radio Calibration.
In Radio Calibration make sure the bars move with your stick left and right for aileron and rudder.
The collective pitch is called throttle and should correspond to your stick movement as well.
The elevator must go down (lower numbers) for helicopter nose down stick movement and must go up (higher numbers) for nose up stick movement.
WARNING !!! MissionPlanner tries to help you and changes your input to the recommended minimum or maximum value. Unfortunately these values are most of the time for multicopters and not for helicopters. Therefore it is recommended to use Full Parameters List/Tree and Refresh to check if the value is what YOU want.
H_FLYBAR_MODE = 1
H_SWASH_TYPE = 1
H_TAIL_TYPE = 1
ACRO_TRAINER = 0 (this gives the FBL full control in ACRO mode)
H_CYC_MAX = 4500 (you adjust this to limit the aileron and elevator output for your FBL setup)
H_COL_MAX = 1900, H_COL_MIN = 1100 (you adjust this to limit the collective pitch for your FBL setup)
H_SV1_POS = 90 (aileron)
H_SV2_POS = 0 (elevator)
H_SV3_POS = 180
Check rudder and swash movement (collective, aileron, elevator) and adjust as needed using
HS1/2/3/4_REV = 1 / -1 (1 or -1 to change direction)
DO NOT use the TX to reverse servo direction !
RATE_PIT_P/I/D = 0, RATE_RLL_P/I/D = 0, RATE_YAW_P/I/D = 0
RATE_PIT_FF = 0.4 (adjust as needed)
RATE_RLL_FF= 0.4 (adjust as needed)
RATE_YAW_FF = 0.3 (adjust as needed)
ACCEL_Z_P = 0.3 (adjust as needed, many helicopters oscillate on collective using standard value 0.5)
DISARM_DELAY = 0 (if you can't arm because after arming software disarms)
WARNING !!! Remove blades or pinion or motor wires NOW.
Check FAIL SAFE, what happens with TX off, what happens with TX on, RX off and Pixhawk on, etc.
Check ACRO mode FBL correction direction before EVERY flight !
Check STABILIZE mode correction direction before EVERY flight !
Landing using any flight mode that uses the barometer can be problematic as there is quite often a dramatic pressure change at touch down.
In case you have problems using Loiter, Andrew Tridgell suggested to try :
I'd suggest you halve the following parameters:
and also drop VEL_XY_FILT_HZ to 2Hz.