Need assistance for private Dual Tailsitter project - anybody?


I’m trying to build a Dual Tailsitter. All the equipment is here (Taranis, pixracer etc.) Things don’t seem to go too well so far. I have for example following questions:

  • Should the GPS be oriented in drone mode or in horizontal flight mode? (the pixracer is oriented in drone mode)
  • How to adjust servo centre position, trims and ways individually?
  • What flight mode is best for take off?

The 1st goal would be to have a stable hover flight and 2nd the transition. If somebody is willing to help getting it in the air via PM I would happily pay some money. I don’t want to bother you here with too many questions. I’ve seen other people to get it in the air so it must be possible : )

Thanks and merry Christmas!

Hi @Derriell,

With a newer GPS (eg ublox m8n) I find you can often get away with mounting it for forward flight, but this depends on your usage a little bit. Typically you intend to transition to fixed wing flight as soon as possible, and stay there for the majority of the time.

For servo position I generally try to get it as close as possible mechanically first. After that you can adjust the trim per PWM or control axis if needed.

Best flight mode for takeoff? Depends what you’re trying to do, but bring it up slowly. Treat it like a multicopter in manual/stabilized mode first, do some tuning, then try altitude control mode, then position control mode.

Good luck!

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Hi @dagar

Thank you!

It worked! After carefully calibrating it hovered in “stabilized” VTOL-mode. Today even “Position-hold” and “Land” worked! : ) As GPS I have a random Chinese Ublox m8n (gets ~14 satellites). Though I have to rearrange the motor cables and stuff, they are probably distorting the magnetometer.

Where can I trim the PWM_MAIN_5 & 6? I can’t find it in Dual Tailsitter. I saw it in the documentation that it is available for other chassis but not here. Only PWM_AUX_5 and 6.

I find it very hard in “stabilized” to descend the plane. How can I tune it? First I used 3 blade 104.5 propellers, but I found that 2 blade 105 propellers would have faster airflow and thus give better control over the rudders in descent.

Thank you!

Look for the parameters PWM_MAIN_TRIM5 and PWM_MAIN_TRIM6.

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In what position is the GPS orientated if turned like following:

  • turn it up it is facing upwards
  • then turn it so that it is pointing to the left with its upper side facing me.

As I understand this position would be: 90 Pitch 270 Yaw; but I can’t find it in the settings What am I doing wrong?

Btw: I found RC5_TRIM but no PWM_MAIN_TRIM5