How to set the desired airspeed for a glider

Hellow there,
I am trying to fly my glider with ArduPlane.
I want to command my glider to fly at a specified airspeed.
How can I set the desired airspeed?
By what parameter can I set the desired airspeed?
I know there is a parameter TRIM_ARSPD_CM but this parameter is used in automatic throttle mode. I want to fly my glider at a specified airspeed with the throttle be shutted off.

looks like TECS tuning and Synthetic Airspeed if you don’t have an airspeed sensor.

Thank you Allister,
I looked TECS tuning but no parameter to set the desired airspeed was found.

According to TECS tuning: “When the soaring feature is in use and is requesting the TECS shut off throttle to glide, a TECS_SPDWEIGHT value of 2.0 will automatically be used providing an airspeed estimate is available.”

I’ve never setup a glider (at least not with an autopilot, but it’s on the to-do list), but if I read this correctly then if TECS_SPDWEIGHT is 2 then the TECS controller use pitch to control airspeed, and prioritize that over maintaining altitude. You would still set the desired speed with TRIM_ARSPD_CM.

Thank you Allister,
I agree with your understanding that if TECS_SPDWEIGHT is 2, then the TECS controller uses pitch instead of throttle to control airspeed and try to keep airspeed. Glider will looses altitude.
So I already set it 2. Then I wanted to set the desired airspeed and checked
the TRIM_ARSPD_CM at the Full Parameter List and found the following explanation.

“Target airspeed in cm/s in automatic throttle modes. Value is as an indicated (calibrated/apparent) airspeed.”

I am a new commer to the ArduPlane and this is my first time to try a autopilot on a glider. So I was a little bit nervous. This is why I posted this question.
Anyway I will set the desired speed with TRIM_ARSPD_CM.
Thank you again.

I’m going to guess that TRIM_ARSPD_CM specifically refers to throttle because 1) that line was written before soaring options were available in Arduplane and 2) I’ll guess that 99% of the users here are flying powered planes that are using throttle.