Flight mode just to change roll

is there is flight mode that hold altitude and speed, and let the operator just to control the roll?

No, there is no such flight mode.

Copter doesn’t have a mode like that, but Plane’s FBWB is effectively what you’re asking for. Something similar could be implemented without much trouble for Copter.

If your autopilot is capable of running Lua scripts, you could write this as a script using GUIDED mode. Such a script might be a fun challenge to write. I might tackle it if there is a bit of interest generated.

I’ve also done it in EdgeTx. With the flip of a switch I can control speed/pitch of the quad with a slider and just steer it around with yaw.


If your throttle control is good, DRIFT mode might work well, also.


Attached is my attempt at scripting such a flight mode. I recommend testing this in SITL before using it on a live Copter. I did test it live on a 550 series quad, and it worked great until I discovered some buggy behavior and crashed twice. The version attached below contains bug fixes and should no longer cause processor panics. Overall, I think it’s a pretty fun mode to use!

The following comments provide some usage instructions:

Copter FBWB ArduPilot Lua script

Provides guided commands to Copter similar to Plane's FBWB mode.

To enter scripted FBWB mode, simply select GUIDED mode above FBWB_ALT_MIN.

RC throttle input sets forward speed as a percentage of WPNAV_SPEED.
RC roll input sets turn radius, calculated via percentage of ANGLE_MAX.
RC pitch input sets climb/dive angle via percentage of ANGLE_MAX.

Additionally, the following custom parameters influence behavior:
FBWB_ALT_MIN: (meters) minimum altitude at which mode can be activated
FBWB_PIT_INV:  set non-zero to invert pitch stick input
FBWB_PIT_EXPO, FBWB_RLL_EXPO, and FBWB_THR_EXPO: RC stick expo for each input

Expo values should be between 0 and 1 as a percentage of expo desired. Setting
zero results in linear stick response (no expo).

CAUTION: This script is capable of engaging and disengaging autonomous control
of a vehicle.  Use this script AT YOUR OWN RISK.

copter-fbwb.lua (5.5 KB)

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