to much trim needed in acro mode

[odem]

Having an issue with a new quad that I have been building. During its first flight I was trying to trim it in acro mode and it keep wanting to lean to the right. Had the sub trim set to -120 (thats full on the 9x) and it was not enough to correct it. Basically with the trim centred the aileron needs to be about half way to balance it in the air.

Have checked the following:
- props are the right orientation and not upside down (hehe has happened)
- motors spin in the direction seen in the gui
- gui shows the roll and pitch the same as experience on the quad
- props and motors have been balanced (not relative to this issue)
- center point of gravity

The rig:
- Hobby king Talon 2 frame
- RC timer ESC
- Turnigy NTM 28 1000kv short shaft with the prop adapter
- HK MultiWii Pro configured as Quad X
- Multiwii 2.2 firmware
- Turnigy 9x radio

This quad does fly and its really stable in the air (compared to others I have built), it just have a massive lean to one direction.

Interesting it leans to the left alot and a little forwards and yaws to the right alittle. While balancing the motors I did notice one seemed to have a higher rpm then the others, they are all marked as the same KV. So it would make sense that one motor is at a higher RPM causing this effect.

Would like to confirm the following:
1) I assumed that if one motor has a higher KV then the others, at hover (in acro mode) the gyro would balance it out.
2) the point of the initial trim in acro mode was to get the radio and the flight controller to agree where centre is. Its not about balancing the air frame or motors.

Any ideas on how to fix this?

[tovrin]

have to ask the obvious, did you calibrate the ESC's using the sketch?

//#define ESC_CALIB_CANNOT_FLY // uncomment to activate

also, excess vibration can cause weird issues like this, does the gui show a lot of vibration while flying?

[odem]

No I have not. Using RC timer ESC that has been flashed with the simonK firmware. Does this mean there is no point in calibrating the ESC's ?

The frame has very little vibrations and the flight controller is mounted on foam. The GUI graphs look a lot better then my Tri

[odem]

well tovrin you were correct [face palm]. Calibrating the ESC's fixed the issue.

Thanks for the suggestion