My X8, still no success.

My X8.

I'm at my wits end!! Any help will be VERY MUCH appreciated.

Things I have changed  and tested after each change with no results:

1) Level the APM to the center line of X8, re did all "Initial Setup" in MP
2) remove the end point on travel, was 80% now 100%, re-did all "Initial Setup" in MP
3)Changed firmware to V2.76 from V2.78b, and also re-did all "Initial Setup" in MP

4) I have also re-leveled the plane with a 5* pitch up, and still no success.

5) I did a ground check by double checking control surface movements.

 a) manual mode..Pull stick back, both elevons go up. Pushed stick forward, both elevons go down. Stick right, right elevons go up, left elevons goes down. Stick left, left elevons go up, right goes down.

 b) FBWA mode…. Put nose up both elevons goes down. Put nose down, both elevons go up. Banked to right, right elevon go down, left elevon goes up. Bank to left, left elevon goes down, right elevon goes up.

Every thing "Ground tests" great.

Still, no change, when going into FBWA or Mission, or RTL it will start descending and I have little control if any "Nudging". I have to go into "Manual"

I have almost no trim in MANUAL MODE, if any would be 3mm (1/8") up. It is touch nose heavy.


See attachment...logs files


PS, can anyoneS download there Param file or Tlogs of there X8




Thanks for any help.



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    • Moderator

      Totally agree regarding the CG and spin, The X5 has exactly the same problem.. keep the CG forward and getting flying even if it has a lot of up elevator to keep it level. then slowly move it back until you get the response you want and then leave it alone, never fly it without reflex or you will end up buying a new one and picking pieces of foam from a large area!!. my X5's have the CG abour 15mm in front of the advertised position. works great.

    • I agree,

  • Ok,

    You need to get the GPS as far away from all the electronics as possible.

    There IS enough space in the X8 to space all the different bits far apart.

    As Graham said, you need a properly working pitot setup.

    APM needs accurate, or at least, repeatable airspeed readings.

    I had a X8, but found the hand launch in strong wind a bit daunting.

    Not too sure if my pictures are still in the blogs somewhere ?

    Mine flew very well with APM

    What is the servo doing?

    And yes, the wiring is a mess :-)

    • Gustav,

      Thanks for your time. Looks like all you guys have the same answer to my electronic setup.. too close and messy.

      I will definitely re- arrange all my electronics.

      You stated, "What is the servo doing?" What do you mean by that?

      Thanks, Brian

    • I was just wondering what you use it for :-)

    • Moderator
      When you refit the equipment also make sure your APM and the GPS module are lined up correctly with the aircraft!
    • His GPS doesn't have a magnometer so it doesn't need to be lined up with anything.
      What is that servo in the payload bay for?
    • Moderator
      The APM. Does need to be lined up
    • I don't run a folding prop. Cheat mans way to stop the prop. It has a peace of fuel tubing at the end. I flip the switch and it will push the tubing into the blade to stop it, pretty much horizontal. It not prefect but it's ok. ( Not my ideal, found it on a forum )

  • Moderator

    A couple points with respect to the X8 but flying wings in general:

    - You need the 3mm up elevon for level flight, ie a bit of reflex.

    - When you do your radio calibration make very sure the sticks go to the four corners, not just up/down left/right otherwise the throws that the APM will use will be reduced.

    Pitch_Max and _Min control the pitch in any Guided mode like FBW-A or RTL, etc, so you can increase those (but do the radio calibration first!) if you're getting very little response in FBW_A mode (This mode uses throws that the APM would use in a Nav mode, except you're providing the nav inputs).

    Get FBW_A mode working properly first before even trying any other mode and thereafter all the other guided modes will work fine.

    As Tommy said about your magfield, you must get your compass away from any DC wires, away from your ESC and any other metal otherwise the induced magnetic field will play havoc on your navigation. As you're using the onboard compass consider getting an external one or move your APM away from all other electrical parts. Also cable tie your wires up neatly away from the APM.

    Check your altitude before taking off, if it's more than 2-3m out then do a preflight calibration in the actions tab (it should be 0m).Lastly make sure your airspeed sensor is working 100%, APM will put the nose down if it thinks it's too slow.

    (BTW, we've got six X8's for sale if anyone wants them)

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