Quad X Problems

[ikem]

Having some problems with my new quad. It has a multiwii controller running 2.1 right now. Running 920kv motors, 40A Escs, 3s 2200, 10x4.5 props.

What is going on, is that when throttling up and trying to do a simple hover, its altitude will not stay constant. I know this doesnt have alt lock or anything, but this is bobbing up and down pretty bad. (up to 10ft strides) and it is really unflyable like this. This also happens in auto level mode.

I have also tried getting my trims right, but cant get it to hover (besides the alt problem) still.

Also, does anyone have any suggestions on PID settings?


Thanks in advance, Mike

 

[Craftydan]

Mike,

does it seem like your motors are surging or is it just hard to keep at a happy hover speed?

 

[Cyberdactyl]

And you've done ESC calibration and flashing?

 

[ikem]

Escs are flashed and calibrated. I did the calibration through the multiwii as directed in the manual.

It doesn't sound like they are changing speeds, but they are just gaining and losing altitude without any input.

 

[ikem]

ok would this make any sense, (i only tested this in my basement) but I switched the direction of the Z acc and it seems more stable. I will test outside later.

 

[Cyberdactyl]

Let me also throw in another wild variable for you and a caveat for anyone while building.

I almost made this mistake myself in the past.

In the mist of cutting, trimming and soldering the multi-strand silicone wiring we all use from HK and other hobby shops, we all get ultra thin, very short strands (~3mm) everywhere. Wires so thin and short they are hard to spot. It can be relatively easy to entrap a strand inside ESC shrink after flashing, or have one laying on the open face of a FCB causing any sort of weird problem.

It's a rather remote possibility, but something that could cause a world of grief, since it would be impossible, or next to impossible to spot and diagnose.

 

[ikem]

well i got it outside, and it is much better. Hovering low it still drops, but I'm guessing that is just because there is bad prop wash circling around, but i crashed it too... flew great for about 8 min and was bringing it back in and drove it into the ground... Broke an arm, i fixed that with epoxy, and 1 motor (one on the broken arm) had a lead ripped out of it. Un-repairable. So i have ordered a new motor, and should be back up and flying.

Is there anything I could do to strengthen the leads around the motor base?

 

[xuzme720]

Epoxy. David shows how in this video at about 7:20. He's doing the DT750, but the same technique can be used on any bell motor.

 

[pelotron]

If you epoxy the wires be careful about not getting any on the motor bell. I accidentally fused a motor up once...