Shutting off specific motors during flight?

Frank_Lucci · January 31, 2023, 8:14pm

Hello, I have recently made a VTOL plane that has 3 tilting motors and they all tilt forward during flight. The front two motors will have folding propellers so they can shut off and allow the back motor to propel the plane most efficiently. In order to do this, I need to have a way to control the motors so that when I am in fbwA or manual mode, I can shut off the front two motors, motors 1 and 2. I would like to know if this is possible and if so, how to do it?

thank you for your time and help,
Frank Lucci

Chad_Frazer · February 3, 2023, 4:04am

I recall the dev’s saying that this was a flight mode that they wanted to add but as of a year ago (maybe longer) I’ve not seen it. I wanted it too because one motor swinging a larger prop is more power efficient than two swinging smaller props.

I’m not sure how you will account for a folded prop that gets spun up in the air as it seems to be a high likelyhood that they will impact your airframe, perhaps a diagram??

jamoser · February 3, 2023, 8:00am

How about a horizontal / vertical sensor, which automatically turns on/of the front motors ?

iampete · February 3, 2023, 8:19am

We have a example Lua script for this.

github.com

ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/applets/forward_flight_motor_shutdown.lua

-- This is a script that stops motors in forward flight, for use on tiltrotors and tailsitters
-- Thanks to PteroDynamics for supporting the development of this script
-- Set the motor numbers to stop and configure a RCx_OPTION to 300 to enable and disable
-- Throttle thresholds also allow automatic enable and disable of stop motors
-- slew up and down times allow to configure how fast the motors are disabled and re-enabled

-- Config

-- Motors numbers to stop
local stop_motors = {2,4}

-- motors should be shutdown if throttle goes lower than this value (%), set to > 100 to disable auto enable/disable
local throttle_off_threshold = 50

-- motors should be re-enabled if throttle higher than this value (%)
local throttle_on_threshold = 75

local slew_down_time = 5 -- seconds
local slew_up_time = 1 -- seconds

This file has been truncated. show original

Instructions here:

github.com

ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/applets/forward_flight_motor_shutdown.md

# Forward flight motor shutdown script for tailsitters and tiltrotors

This allows to shutdown selected motors to be stopped once in forward flight for efficiency.

Set the motors to shutdown in with the `stop_motors` variable. Enable and disable the functionality with a RC switch with options 300 (Scripting1).

Motors will automatically be shutdown if forward throttle is lower than the value set in `throttle_off_threshold` (50% by default) the motors will then be re-enabled if the throttle goes above the value set in `throttle_on_threshold` (75% by default).

Time for stopped motors to go from throttle value to 0 and 0 back to throttle can be set with `slew_down_time` and `slew_up_time`.

Frank_Lucci · February 3, 2023, 11:06pm

Thank you guys for the information, this is a tricopter vtol will 3 tilting motors when the front two shut off during forward flight they will gradually decrease in speed and the propellers will eventually fold kind of like the ones you see on a glider. I plan on just makeing it a switch for now so it gets up to speed in forward flight and then i flip a switch deactivating the front two motors leaving the backone to propellel