Servo travel distance in FBWA is greatly smaller than MANUAL

ArduPlane Plane 4.4
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1

Greetings,

so I have noticed during ground checks that the servo travel distance in FBWA is greatly smaller than the distance in MANUAL mode. I am aware that by increasing pitch/roll P term increases the throw.

Is it a good idea to increase P (and I term) so much so that it matches the MANUAL servo travel distance? I am worried about increasing P so much that I will cause instabilities during flight that I don’t have a way of predicting at ground tests.

Is there another way to increase the throw without messing up with the PID?

2

This is normal on the ground. Tune the PID controller based on flight performance, not what it’s doing on the ground.

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3

I see your point.

However, I had an incident earlier where with the default PIDs, and FBWA mode, my aircraft couldn’t takeoff. It was like the servo throw was not enough for the plane to rotate. After altering the pitch P and I terms (x2) the plane successfully took-off.

This is my main concern.

4

You should not use assisted and automated modes like Stabilize or FBWA before doing autotune, especially for takeoff.

5

We want to use an assisted mode due to the novelty of the configuration and the inexperience of the pilot in that type of configuration.

The purpose is to protect the aircraft as much as possible from getting damaged. As soon as it gets in the air we will use an Autotune mode.

I can see in the forum’s previous posts from @tridge that he mostly performs maiden flights in stabilized modes.

6

What kind of plane is it? It’s normal to maiden a plane on default PIDs. As long as the servos have proper travel in manual it should work. Doubling the PID values is very likely to induce oscillations in any stabilized mode, and the only safety would be to go back to manual mode.

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7

can you just lower the cruise speed and/or min speed? doesn’t the plane reduce servo travel based on airspeed versus these speed settings?