uncontrolled yaw on takeoff

[javaboy]

I am a newbie here but have some experience with rc. I built a droidworx Y6 with WKM and it flew very well for the first week. However, I had a mishap on landing and broke a boom. After replacing it and re-soldering the motors I took it out for a test. As I lifted off the bird immediately began twisting in a yaw that did not respond to the stick. Everything else seems fine as it is stable and I'm able to bring it down softly before it goes up higher. Recalibrated the compass and the transmitter and the same result. I didn't want to push my luck by testing much further but it seemed pretty clear that the left stick was having no effect on the yaw. I figure I must have something misconnected or miswired. I'd appreciate any suggestions as to how to best troubleshoot this. The good news is everything was working just fine. Obviously there is some sort of bone-head operator error involved and I'm hoping the symptoms suggest what I did wrong to some of you experienced guys.

THANKS

 

[therealharry]

aloha Javaboy. I am not an expert by any means but I do have a little time under my belt. Usually when you have uncontrolled yaw and no response from controls then one or ore of the arms or motors is out of plane with the rest. Set the copter on something level and relevel and strengthen your engines and arms. Bites as you will have to do a rebuild awesome as it will fix the problem! Good luck.

 

[javaboy]

I really appreciate that suggestion. .... Say, let me ask something that may be stupid. You see, this is a Y configuration with one motor above the other upside down. I've got my props labeled so I know which ones go underneath and which ones go on top but I must confess I wasn't as careful with identifying my motors. Is there any chance this thing would even fly if I inadvertently mounted the upper motor down below and put the lower prop on it and vis-versa with the lower motor now on top with the upper prop? I'm assuming it wouldn't even fly but I really don't know that much about these multi-rotors and since it flew perfectly before I changed out the boom I figured I'd ask.

 

[therealharry]

I am not up on y configurations but it is extremely important to make sure of the following
1: all ESC are plugged into the correct controller port. Can not check enough and make sure again and again
2: blades are on correctly
3: engines are in correct place
Label everything in a place easy to see when connecting
4: make sure that your controller unit imu Wookong, AHRS xaircraft not sure what model you have is centered in craft and level and pointing forward directly no slight side to side. Make sure firmly affixed to craft.

Hope that helps.

 

[Jake Bullit]

Check out the recent thread by zaxis , they had similar problems with a y 6.turned out to be an alignment issue.

Sent from my HTC HD2

 

[javaboy]

Well, my stars and little comets. Turns out that I had, indeed, flipped my motors over without realizing it. I reversed them and replaced the props properly and it fles perfectly. I count myself lucky that it flew at all with the motors upside down. Obviously, the yaw was being produced because two of the booms were oriented properly and the replaced one had the top motor upside down with the counter prop on it and the lower motor upright with the regular prop. Sheesh. I feel like an idiot but am so pleased everything works now. I will pay MUCH more attention to my wiring and sockets in the future! Thanks for everybody's help.

 

[therealharry]

Congratulations! We all mess up!