Lots of trim due to frame?

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mattchase
Posts: 2
Joined: Wed Jun 22, 2011 3:13 pm

Lots of trim due to frame?

Post by mattchase »

I built my own quad frame using square aluminum tube and plastic junction box covers. It has a lot of right drift and right yaw when flying which I'm able to fix with TX trim, but it takes a lot of trim! I have about 15 left yaw and 25 left roll on the trims, is that too much? Could the frame be what is causing this issue?

It isn't perfectly built, but most the measurements are very close. The span from motor to motor across one arm is 26-3/8", the other motor to motor pair is 26-7/16". The span from motor to motor (measuring right front to left front, left front to left rear, etc) is 18-5/8 for two of the measurements and 18-7/8 for the other two, so about 1/4" difference. Is that enough to throw off the balance and cause all the trim needed? As far as I can tell the motors aren't tilted in different directions, and I did balance the props. It flies pretty well with all that trim, I'm just wondering if it could be better and what is causing it.

The only other thing I noticed is that if I spin the motors by hand (with power off) one of them is a little stiff (it spins smooth, just not freely), while the other three feel more neutral / free. Some one suggested maybe the motor had tight bearings and to check how hot they get after flying, they all feel about the same temperature after a couple of minutes flight.

Thanks.

dodecopter
Posts: 35
Joined: Fri Jan 21, 2011 7:37 am

Re: Lots of trim due to frame?

Post by dodecopter »

hi,
if frame is some distortet, not all motors+props might have the same , exact vertical direction.

had a yaw problem with one of my quads with DIY alloy tube frame too - a little skewing one whole arm to the other direction than yaw drift solved that problem.
be careful and skew only very little, unless you want to let drift yaw the other way ;)


an 10mm open-jaw wrench is the perfect tool to fix 10mm quare tube alloy frames... http://www.google.de/search?q=maulschl% ... 40&bih=747
..

mattchase
Posts: 2
Joined: Wed Jun 22, 2011 3:13 pm

Re: Lots of trim due to frame?

Post by mattchase »

That's kind of what I was thinking. I don't see any bends in the arms but some of the screws did sink down into the thin metal walls some, which probably caused just enough of a twist in the metal. I will try using a wrench to twist a couple arms very slightly.

Thanks!

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