Initial tune for large VTOL

ArduPlane Plane 4.2
1

We are trying to get an initial tune in plane mode for our large VTOL after getting it tuned well enough in quad mode thanks to the helpful initial tuning calculations and tuning instructions on the wiki. We tried the default plane parameters but had essentially no roll or pitch authority in plane mode and didn’t have enough space (or comfort) to give the autotuner time to improve control.

This thing’s takeoff weight is about 24kg, wingspan is 3.5m, and stall speed is 19m/s. The manual says that the default parameters are not suitable to safely fly “full size, full speed airframes”, which we now believe ours to be. But we are not sure how to safely select initial parameters for something this size that will let us feel confident maneuvering it before and during the autotune, and to perform the initial airspeed calibration. Iterating parameters on this thing is a huge pain because the VTOL motors only have enough battery for a single flight, and we aren’t even quite sure where to start with that.

We did look at the example parameters page (our airframe is similar to the Mugin) but aren’t sure how to adapt those values to the new version 4.1 controller.

2

Hi

We have a similar VTOL 3 mt wings, 24kg, here is the parameter file, pls be advice may be our PID wont work for you, but as a reference or start point could be usefull.

And be carefull because we only have the Multirotor PID, we havent made the plane VTOl yet.

Hope this can be helpfull
parametrosPrimerVuelo.param (20.7 KB)

3

I’m not an expert at this stuff, so take this with a grain of salt.

Have you looked at Roll, Pitch and Yaw Controller Tuning — Plane documentation ?

Have you verified that the underlying airframe has the desired control authority in plane mode?

It might make sense to fly it (maybe even in manual mode) with blackbox logging enabled to measure some basic parameters like max achievable roll and pitch rate of change, throttle level for cruise speed, climb rate at full power, glide rate, ensure the CG is correct, determine the correct value for TRIM_PITCH_CD, etc.

4

the autotune process is quite agressive and i have seen one bigger VTOL crash with the big deflections it uses.
For our VTOL we reduced the angle the autotune does. It might not provide the best tuning results, but it worked quite well. Of course we had an initial tune before and a manual fine-tune afterwards, following the instructions.