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Is my CG terribly off?

Posted by Raph on January 17, 2014 at 7:20am

Hi all - recently build a quad and have been testing it the last few days.

ArmExtensionGif1.gif

Yesterday when I came to land I noticed the copter was leaning forward a lot - so much I had to pull back the stick to level and land nicely (otherwise it would of crashed on it's face). When I got to the copter the front right motor (1) was much warner than the rest.

Here are the motor outputs during this event:

copter-badmotor1.JPG?width=500I was surprised to see how diverged the motors were - granted this was a normal flight, not just hovering the entire time.. you can see lines 4400-6000 i was lotering and my 1 motor is working much hard than 3.

I replaced motor 1 with NO changes to my CG and hovered for 15 minutes:

copter-badmotor1replaced.JPG?width=500

I'm just curious if the above is what I should expect, or are my motors still divirging too much due to CG being off? I don't have a baseline for what this should look like, nor offsets of 'acceptable' limits so I would really like some (any) input.

logs attached.

Thanks!

Raph

hovering.log

possible bad motor.log

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Replies

  • Euan Ramsay January 19, 2014 at 2:19pm

    CoG isn't normalyl too bad, if it's only slightly out - the stationary yaw in zero wind will show up any weakness there - a CoG that's off will have the quad start a wide circle, rather than stay on the spot.

  • Stuart Brookes January 18, 2014 at 1:02am

    I personally think that looks fine (hovering log), you could try and balance them out more, but I wouldn't bother.

    edit, great looking folder :)

This reply was deleted.

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