New AQ build - flips after take off

[nikivan]

Thanks, Larry. I haven't touched PIDs, they are defaults. The board orientation always confuses me because there are two arrows marked at the front corner of the board. However, HUD in ground control tool shows correct movements when tilting the quad. This is X configuration and the corner of the board with the two arrows points to the front right arm. Could you please explain a bit more about this string thing? Do you have some pictures? Thanks.

[Kisssys]

Hi NIck,

Before you mess with PID's you have to get the throttle in the 700 range in a hover. Your way off. Try a throttle factor of .45 and see what that does.

I built a quad with 4 Avroto's much more rigid than what you have and I was never very happy with it.

Good Luck

[nikivan]

Thanks, Steve. This particular flight was without the payload, so that's why you see it hover with less power. In therms of stability though, adding payload does not make any difference. There is something fundamentally wrong with this build and I am out of ideas for what that is. I will document another flight when it stops raining here.

[LPR]

Nick

The idea with the string is to keep the arms from vibrating sideways. Just have the string rub against the motor mounts and as long as the string is tight enough you should see the sideways movement stop.

Larry

[nikivan]

[LPR]

Nick

It doesn't matter very much what kind of string. I use Vectran because I have some and it does not stretch.

Larry

[nikivan]

Here is a short video showing the issue. Enclosed here is also the log from this test.

http://youtu.be/Xb78kgi3sHA

Your thoughts?

[JussiH]

Hi Nick

Looking at the video, I would say that it looks a lot like something is screwed with the mixer and/or motors connection. A incorrect mixer table, or just a motor connected to the wrong output, will cause this kind of behavior.

Looking at your motor output for roll, pitch and yaw, something is definately wrong and it also points to incorrect mixing or output connection. You got a huge split between roll and pitch output.

Best

Jussi

[Kisssys]

As Jussi said something is set right. Are you sure your board rotation is correct?

[LPR]

Nick

I have a lot of experience with trying to fly a quad with it setup wrong. Everything from having the motors connect in the wrong order or having the motor mix with the "-" in the wrong place. Your video looks like that could be the problem.
To make sure I have the motors connected right I change the motor mix so only one motor is will respond to pitch and roll inputs with the props off.

I set all pitch and roll setting to zero except for one so I can make sure each motor is responding the way it should.
Touching the motor lightly as it spins you can feel the rpm change.

Larry