TBS Discovery Pro with APM 2.6 maiden flight

Hi everyone,

I had my maiden flight today and it went not too bad... it's flying, but.....

...of course some problems.

I really need some help to solve them.

- First of all in "Altitude Hold Mode" it goes slowly either up in the sky or down and eventually lands.

Barometer sensor is working correctly, I checked. 

I guess it's a parameter problem.

- It twitches sometimes when it's in either "Alt Hold Mode" or "Loiter Mode" also when I fly aggressive in "Stabilize Mode".

Again parameters...

- It's flying sluggish and needs a lot of corrections on the sticks. Once it's flying in one direction it keeps drifting when I let the sticks go. It's not in Acro mode.

I have also an 3DR Quadcopter and this one doesn't drift further when I let the sticks go e.g. in forward flight.

Wrong parameters I think.

- When I use the ch7 or ch8 option "ResetToArmedYaw" the copter is turning left 90 degree. It should turn to face the same direction that it was facing when it was first armed. Again my 3DR Quadcopter does this without problems. My compass is mounted and calibrated correctly and points exactly where it should at Mission Planner's compass gauge.

No idea what could cause this...

In the Arducopter V3.1-rc5 Quad is a function called "AutoTune"  http://copter.ardupilot.com/wiki/autotune/

Has anyone tried this successfully ?

Offset angles for the TBS Discovery arms:

I changed the standard angles of the V frame in the firmware version 3.0.1 to:

}else if( _frame_orientation == AP_MOTORS_V_FRAME ) {
// V frame set-up
add_motor(AP_MOTORS_MOT_1, 55, 0.7981, 1);
add_motor(AP_MOTORS_MOT_2, -125, 1.0000, 3);
add_motor(AP_MOTORS_MOT_3, -55, -0.7981, 4);
add_motor(AP_MOTORS_MOT_4, 125, -1.0000, 2);

Original it's 45, -135, -45, 135.

I checked vibrations and electric interference and it's all well within the limits. Compassmot has in full throttle only 4% interference to the compass. Limit is 30%.

My TBS Discovery Pro is all original like 9x5 props 900kv motors exept I use APM 2.6 as Flight controller and not Naza.

I would appreciate any help.

Here are some pics and the log file of this flight.



2013-11-14 15-09 4.log

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  • HI Steffen, Did you get the 2.6 working well with the TBS Pro? I have the pro with the Naza, but really like the 2,6 on my hex and would like to change if it is not too much trouble to get it working.


    • Hi,

      It works great now, but it's not a plug and play thing. You have to make a APM casing in addition to the original plastic case.

      The reason is that the position where you place the APM, either between the frame plates (original position of the NAZA) or on the top plate, that it is in the prop wash (heavy turbulence from the props). The problem is that the props are either way above the APM blowing down on it. This causes a high pressure reading on the Baro sensor.

      So you have trouble in Althold and in any mode which uses the Baro sensor like Autoland, RTL, Land, ...

      The copter is bouncing several times up and down several feet when it's touching down in e.g. RTL.

      My solution is to encase the APM airtight with kind of a snorkel attached which reaches above the props to avoid the prop wash.  I build a box out of thin cardboard, like postcards, put it over the APM attached a plastic tube as a snorkel and cut small wholes on top to get the wiring out. Then sealed everything with a hot glue gun. You need to be sure to seal the tiniest gap or whole !

      Cut a small door for the USB connection on the side and close it with tape so you can easily open it again when needed. 

      If you have a APM with strait up pin out, you can place it between the frame plates. If you have angled pins on your APM you need to place it on the top plate for space reasons. 

      I now it's not the prettiest solution, but it works great and it is worth it !

      Maybe you can find a more cleaner solution. 

      If you need a more detailed explanation or pictures, even the parameters from my TBS Pro, I'm happy to provide them.

      • I recently had the same kind of problems with my TBS Discovery with APM 2.6. I had some success with dialling down the altitude P value (gives softer response to altitude input data), and also dialling down the vertical time constant (see http://copter.ardupilot.com/wiki/arducopter-parameters/#Vertical_Ti... ), which gives less weight to the noisy barometer data and more to the accelerometer data (these are mixed to estimate the altitude). Seems like you already found a good solution, but I just thought I'd mention it in case someone else has similar problems. 

  • Have you done all of the Pre-flight and Maiden-flight steps in Randy's youtube videos?  You altitude drift in alt-hold makes me think your THR_MID may not be set.

    Is your APM protected from wind and sunlight?

This reply was deleted.


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