Stability Issues

Hi All,

We've taken a 3DR Quad and changed it a bit to try and get more payload and more flight time. Here are the current specs:

Motors: T-Motor MT3520-11 400KV

ESCs: Phoenix Edge Lite 50 Amp

Props: APC 13 x 4.7

Battery: Zippy 5S 5000mAH

RC: Spektrum DX8

APM Model: 2.6 with 3.0.1 Firmware.  The APM back rail is getting power from motor 4 ESC and the front rail is getting power from motor 1 ESC.

 

 

The APM has been mounted on some foam to reduce vibrations. All wiring has been checked, double checked and all calibrations that could be done have been done as well (compass, radio, accelerometer) but we cannot get the thing to fly without doing flips! Here is a video of the issue which shows two of the flights.

 

 

 

I've looked around on the forums and Google and have seen other people with similar problems but theirs were the result of incorrect motor wiring. So my question is... does anyone know what is going on here and how I can fix this?

 

Thank you!

-Oliver

2013-10-06 18-03 9.log

2013-10-06 18-03 9.log.gpx

2013-10-06 18-04 10.log

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Replies

  • MR60

    I would suggest that you use smaller props or increase your craft weight. It is still way overpowered and P @ 0.1 is still a lot.

  • So thanks to Andreas, we can move laterally now with the drone nice and smoothly. HOWEVER... as soon as a strong yaw instruction is given the copter flips over... any suggestions to how we can fix that issue?

  • MR60

    Can you explain the foam that the APM is mounted.  Is it double sided thin foam tape, or something else?  If something else, then please try the following:

    Enable IMU under logs in terminal mode of MP.

    Hover the craft for 2 minutes.  After the fight, remove power from the APM.

    Remove the foam under the APM.  Replace it with double sided tape or double sided foam tape (thin).

    Hover the craft again for 2 minutes (use pitch and roll as little as possible letting the craft drift if necessary).  Then post the logs of both flights.  I'll run them through the stability program.

    My guess is that APM vibrations will decrease and control will increase if you get rid of isolation materials.

    But if you are using thin double sided foam, that is about the same as fixing the APM hard to the electronics platform, which is probably good.  Using this method, you will know for sure if isolators like foam are helping or hurting.  Most pilots do not take the scientific approach of establishing  a baseline for the copter, which if you follow the above procedure, you will be.

  • So after adjusting the RateP and RateR to 0.100, we no longer have a flipping copter but a smooth one!

  • In this video, is that in stabilize or acro mode?

  • - On the ground at say 30% throttle, can you bend the multi in the right direction when you play with the joysticks ? Can you rotate it also in the right direction ? Isn't it inverted ?

    - Next, have you set-up the Quad X or Quad + setting  ?

    - When you lift in stabilise mode ONLY with the throttle and NOT TOUCHING the pitch/roll/yaw, does it remain stabilised ?

    To me clearly something is inverted.or misplaced.

  • That should be very simple to solve by applying the right APM motor number scheme

    Number #1 motor for APM is not #1 motor for KK2...

    So check that than of course double-check proper engine rotation as shown on Mission Planner when you upload the correct firmware (green and blue circles)

    Take off the props first, would you please ?

    Cheers

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