Plane gose CRAZY always Big pitch up + log

Hi all , Come back again after test,

Hardware :

My Own plane , similar to Skywallker ,

Flight controller : Pixhack CUAV .

GPS : Ublux 7

other additional tools ,

Software :

Firmware : Arduplane 3.4

 GCS : Mission Planner.

with out AirSpeed , throttle cruise 60 ,

the plane takeoff good in stab mode then start big  pitch up then stabe while trying to control the plane , many time it make a big pitch up ,

change mode to auto , this time the throttle works good but it did a pig pitch up again to stall level then I take control with stab again many time

I don't know what happen this time and what is the reason of that ,

the log file size is 57 MB and try to add to winrar it become 11 MB but limit attach file here is 7 MB

How to Upload it for you

hope I can find answers for my problem

best regards

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  • Developer

    Hi Abu.  I've posted a response in your other discussion.

    Thanks, Grant.

  • Regarding large log files that are too big to upload, you can save them in DropBox and post a link here to the file(s).

    Tim Shcuh has made some good suggestions, that you have not answered.

    Your plane should be able to fly well in manual mode first... maybe something has happened to the plane's setup since you had your previous autopilot the has gone un-noticed.

    How does the CG balance compared to the suggested CG balance point ?

    Test your plane when it is not windy.

    Can your plane in fact fly straight & level (in Manual flight mode) with around 55% - 70% thottle ?

    If you get some altitude and cut the throttle and without using the elevator, does it dive or does it slow down (stall) then drop the nose speed up climb -> stall  or does it stay at a constant pitch . Like a glide but maybe faster ?

    If it does fly well in manual then consider doing a short flight & perform the auto-tune and be prepared to switch back to manual if there are any control difficulties.

    After that flight  go for another flight with a fully charged battery and try Stabilize & FBWA modes. Agian , if the tuning didn't go well then be ready to switch back to manual.

    I'm not much of a pro in log analysis but the the log you posted seems to that the EKF was ok , vibes I think were OK but it seem to never achieve stable level flight for very long in stabilize mode.

    There a chance that I'm completely wrong about the log analysis though. and I've probably missed some things. I'm still learning how to pick out meaningful things from the dataflash logs, and it's easier do it for a plane that one has personally flown.

    • thanks Chris Card  for your good guidelines ,

      I test my plane again and it's fly very well in Manual and Stab and glide with out throttle ,

      my problem now in auto modes and throttle , I will post it in new discussion , 

      what i want to ask you is , Can I limit my log file size maybe by remove some information that will not be useful for analyze ? coz i see many member post logfile with about 3 MB , and all my logs above 20 MB ?

      regards ,

  • The computer can fly a plane that would be impossible to fly for a human.  You still need to make sure that the plane is at least human controllable if you want to do anything meaningful with it.  Mine can fly completely hands-off which takes a huge load off the flight controller and improves performance since you no longer have the extra drag of all the control surfaces doing crazy things just trying to keep the nose pointed in the right direction.

    • Tim ,

      Before start using Pixhack fmu  I was able to fly perfect with stab mode with APM .

      I couldn't understand the problem reasons , with log file ,

      I think my problem with some parameters.

      Can any one figure out the problem if I post the parameter list I used ?

      today I test the flight again ,

      the plane still pitch up many times ,

      And Facing new problem ,

      with change wind today and without airspeed I set the throttle cruise to 60%  ,, then pitch angle become biger ,

      then set the throttle cruise to 40% the wind change higher then the plane can't fly into the wind .

      How to control the throttle in auto mode and wind speed changes.?

      waiting for any help ,

  • How to upload log file with 57 MB ?

    • Abu,

      I was able to look at your log file and the ARSPD setting were turned off. Sorry this only my limited knowledge. Hope others can help.


    • Brian,

      thanks for your help ,

      of course the air speed is off but i set the throttle trim = 60 %

    • Abu,

      I didn't have anything that will open a rar file. I have a .tlog file that only 2 MB and its about 20 minute long. Maybe you need to look for a "tlog" file. ??


    • Admin

      @Brian S,

      I believe 7-zip will open a rar file and it is free.



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