Adjusting the cruise speed


I want to adjust cruise speed.

At default settings I have a ground speed of about 42km/h (without airspeed sensor), and I think the optimal speed should be lower. In the mission planner I have value “Cruise speed”, default 12m/s. I updated it to 9.5, and also lowered minimum FBWA speed, but don’t see any change in actual cruise speed.

How to set cruise speed?

Are these different settings with RTL speed? For RTL I prefer keep it as is - less efficient, but more reliable.

Is it possible to adjust cruise speed during flight, providing value from transmitter channel, like in iNav?

Regards, Andrey

Cruise speed parameter works only when the airspeed sensor is installed. Without it the cruise speed is set by trim throttle. Changing cruise speed will have no effect without airspeed sensor.
Try to make a Horizon calibration with the plane pointing up 1-2 degrees. This will cause more lift and more drag in horizontal flight. Cruise speed will be lower. Maybe the efficiency will go up maybe down, you have to test.

Thank you, Dmitry.

I will recalibrate Horizon and decrease TRIM_THROTTLE. I can’t test it these days because of rains. Does it make sense to add a airspeed sensor? The flight is stable without it.

Decreasing TRIM_THROTTLE will have little effect. This value is a starting point of the throttle PID, It will increase the throttle to meet the desired altitute. I have TRIM_THROTTLE at 30% and the plane flies level at 35-40%, so it starts at 30, and then feels that it cannot keep up and increases it to whatever it feel best to maitain the altitude with minimum pitch up.
“Does it make sense to add a airspeed sensor?” I Don’t know, it is a matter of cost and time. I will add it on my next plane just out of curiosity.

Tried it yesterday. By reducing TRIM_THROTTLE to 30, I got a significant increase in efficiency when flying in calm weather but a decrease when flying upwind.

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