Airplane moves like a dolphin

ArduPlane
1

Hello everyone,
I have a question about my Jak Crack 55. I have installed a SpeedyBee F405 Mini Flight and flashed Ardupilot with version 4.5. I have set three flight modes. Manuel, FBWA and Acro. In FBWA mode, the airplane is almost impossible to control, neither roll nor pitch. In ACRO mode it flies quite comfortably at times, but at some point it starts to go up and down like a dolphin every second and is then no longer controllable. I have not changed anything in the PID settings or filters. They are preset. I had hoped that the values would adjust themselves to a good value in autotune mode.
What do I have to do to get rid of the dolphin?
What can I change in the settings so that I can control the airplane in FBWA mode?

For your information… I have not installed a GPS or an AirSpeed sensor. The airplane is supposed to fly indoors and be light. I am a beginner and the controller should support me in flying.

Another lock file and my parameters
Log-File
Parameter-File

2

You need to turn the pitch gains down, Its a featherweight 3d plane with enormous flight control surfaces.

3

Thank you … to what value?

5

Thanks for the answer. I cannot find the parameter. There is only this one:
grep PTCH2SRV “Yak Crack 2024-04.06.param”
PTCH2SRV_RLL,0.8
PTCH2SRV_RMAX_DN,0
PTCH2SRV_RMAX_UP,0
PTCH2SRV_TCONST,0.5

6

I think the process has changed since the last time i set up plane.

https://ardupilot.org/plane/docs/new-roll-and-pitch-tuning.html#new-roll-and-pitch-tuning

7

I’m a bit confused. Maybe you have an idea. The value PTCH_RATE_P is set to 0.04. In the documentation, the range from 0.08 to 0.35 is specified. Should I run the whole setup again from scretch?

8

I think you need to reduce it further, most aircraft don’t have anything close to the manoeuvrability of what you are trying to fly. Most planes need 20+ meters to turn, yours could probably do a 180 in not much more than its own length.

reduce PTCH_RATE_D by the same amount

10

I think reducing the value PTCH_RATE_P to 0.02 worked quite well.
Thank you very much for your support

1 Like
11

The Yak 55 flies quite well in stabilized mode. I tried the FBWA mode today. The stick movements for roll and pitch are very little transmitted or have an effect on the rudders. Do you have any idea what could be causing this?

12

its possible i was wrong about it needing to be smaller, try bumping it up. I just looked at the log and it looks like its lagging rather than over correcting.